Thesis

Published on November 2016 | Categories: Documents | Downloads: 42 | Comments: 0 | Views: 869
of 101
Download PDF   Embed   Report

Comments

Content


THERMODYNAMIC STUDY OF TERNARY
REFRIGERANT EQUILIBRIA
A THESIS SUBMITTED
TO THE
UNIVERSITY OF MUMBAI
FOR THE DEGREE OF
MASTER OF CHEMICAL ENGINEERING
(PARTLY BY PAPERS PARTLY BY RESEARCH)
SUBMITTED BY
NILESH WAMAN GONNADE
UNDER THE GUIDANCE OF
PROFESSOR SUNIL S. BHAGWAT
INSTITUTE OF CHEMICAL TECHNOLOGY
UNIVERSITY OF MUMBAI
MATUNGA, MUMBAI-400019
JUNE 2010
STATEMENT TO BE INCORPORATED BY THE CANDIDATE IN THE
THESIS AS REQUIRED UNDER REGULATION FOR THE M. CHEM . ENGG.
DEGREE IS AS UNDER:
STATEMENT BY THE CANDIDATE
As required by the University Regulation No. R.2316, I wish to state that the work
embodied in this thesis titled “Thermodynamic Study Of Ternary Refrigerant Equi-
libria” forms my own contribution to the research work carried out under the guidance of
Prof. Sunil S. Bhagwat at the Institute of Chemical Technology, University of Mumbai.
This work has not been submitted for any other degree of this or other university. When-
ever references have been made to previous works of others, it has been clearly indicated
as such and included in the bibliography.
Nilesh Waman Gonnade
(Research Student)
Certified by
Prof. Sunil S. Bhagwat
(Research Supervisor)
Department of Chemical Engineering
Institute of Chemical Technology,
University of Mumbai, Matunga,
Mumbai-400019.
Date:
Place: Mumbai.
CERTIFICATE
The research work presented in this thesis has been carried out by Gonnade Nilesh
Waman for Master of Chemical Engineering degree under my supervision. I certify
that, it is his bonafide work. The research work is original and has not been submitted for
any other degree of this or other university. Further, that he was regular student and has
worked under my guidance as a full time student at MUICT until the submission of the
thesis to the University of Mumbai.
Prof. Sunil S. Bhagwat
(Research Supervisor)
Department of Chemical Engineering
Institute of Chemical Technology,
University of Mumbai, Matunga,
Mumbai-400019.
Date:
Place: Mumbai.
Acknowledgement
Acknowledging people for their efforts and help is indeed a tricky job especially as
the feeling regarding someone can’t be expressed in words. Still it is necessary on my
part to express my thankfulness to some of the people, who have been kind to me and
sharing hands with me to show me the better way of life where the success lives.
Success is the manifestation of diligence, perseverance, inspiration, motivation, inno-
vation. I ascribe my success in this venture to my research guide Prof. S. S. Bhagwat for
his valuable guidance throughout the project work. His systematic approach to solve any
type of difficulty has helped me during research. His continuous guidance. inspiration,
support and co-operation in each and every respect made me to complete this work. I
am really thankful to him. It is my pleasure to acknowledge him for the freedom that he
has given to me to pursue the research work independently and for his constant encour-
agement with critical appraisal on my work. His guidance helped me in all the time of
research and writing of this thesis.
I would like to specially thank my senior colleagues Sachidanad Satpute, Ramesh P.,
Nilesh M., Manish S., Chaitanya K. who had helped all the times with constant encour-
agement, valuable suggestions and for the stimulating discussions. All were the source
of inspiration throughout my work. I convey my deep sense of gratitude to Bhushan,
Rajesh, Sharad, Anant, Balu, Swapnil, Sarish, Anik, Gorakshnath, Vrushali, Meenakshi,
Amar, Kamalakar, Sachin and Abhijeet for their jovial nature that made lab atmosphere
always friendly, co-operation in thesis work and for all the fun we have had in the last
two years. I wish to thank all my junior lab mates Rohan, Vivek and Dattatraya for their
co-operation during preparation of my thesis.
I have thoroughly enjoyed my research tenure in ICT with Vinod, Ashween, Sachin
Jadhav, Prasad, Kiran Bhor, Amit Mhatre, Nitin, Pravin Tadkar, Somdev, Ashish S., Rahul
B., Mandar B., Nilesh K., Mr. Pravin Bhandari, Abhijeet Mestri, Siddheshwar, Ankush
.......who have made my research experience extremely enjoyable and help me in difficult
situation. I would like to thank them.
Its great having friends scattered in the various labs in ICT. I would like to thank
VGG, VKR, AVP, AWP and PDV lab mates for being friendly to me.
I would also thanks to my BATU class mates Sriniwas, Ganesh P. Kiran , Shriniwas
K., Ashok, Leeladhar and Rohit babu for their co-operation and friendly behavior.
My family members have played a major role. They have supported me during the
course of work in many ways. Without their support, i would not have seen this day.
I would like to thank all my family members Aai, Baba, Nishant and Jayant for their
inspiration, support and encouragement that always made me to accept new challenges
in the life and forge ahead to achive my goal in life.
-Nilesh
Contents
1 Introduction 1
1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2 Refrigeration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2.1 Vapor Compression Refrigeration . . . . . . . . . . . . . . . . . 6
1.2.2 Vapor Absorption Refrigeration . . . . . . . . . . . . . . . . . . 7
1.3 Ammonia - Water Mixture . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.4 Objective of the Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2 Literature Survey 10
2.1 Literature Survey for Ammonia - Water System . . . . . . . . . . . . . . 11
2.2 Literature Survey for Ammonia - Water - Salt System . . . . . . . . . . . 13
3 VLE of Ammonia - Water System 16
3.1 VLE Equations for Ammonia - Water Binary System . . . . . . . . . . . 17
4 VLE Measurements of Ammonia - Water - Salt System 22
4.1 Experimental Set up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
4.2 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.3 System Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.4 Result and Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.5 VLE of Water - Salt Binary Mixture . . . . . . . . . . . . . . . . . . . . 26
4.6 VLE of Ammonia - Water - Salt Systems . . . . . . . . . . . . . . . . . . 29
4.6.1 Effect of Acetates (CH
3
COOK, (CH
3
COO)
2
Cu) . . . . . . . 29
i
Thermodynamic Study of Ternary Refrigerant Equilibria
4.6.2 Effect of Ammonium Sulphate ((NH
4
)
2
SO
4
) . . . . . . . . . . 33
4.6.3 Sodium Thiocyanate (NaSCN) . . . . . . . . . . . . . . . . . . 36
4.6.4 Effect of Nitrates (NaNO
3
, KNO
3
) . . . . . . . . . . . . . . . 38
4.7 Data Fitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.7.1 Modeling of Ammonia - Water - Salt System by Redlich - Kister
Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.7.2 Modeling of Ammonia - Water - Salt System by NRTL Equation . 54
4.7.2.1 Modeling of Ammonia - Water - Salt System by Psu-
dobinary Method . . . . . . . . . . . . . . . . . . . . 56
5 Conclusions 65
6 Future Scope 67
Nomenclature 69
Appendix 71
References 84
Synopsis 87
ii
List of Figures
1.1 Block Diagram of Vapor Compression Refrigeration system. . . . . . . . 6
1.2 Block Diagram of Vapor Absorption Refrigeration system. . . . . . . . . 8
4.1 Block Diagram of Vapor-Liquid Equilibrium set up. . . . . . . . . . . . . 23
4.2 Vapor-Liquid equilibrium of Pure Water System. . . . . . . . . . . . . . 25
4.3 Vapor-Liquid Equilibrium of Ammonia - Water System. . . . . . . . . . . 25
4.4 VLE of Water - Potassium Acetate. . . . . . . . . . . . . . . . . . . . . . 26
4.5 VLE of Water - Copper Acetate. . . . . . . . . . . . . . . . . . . . . . . 27
4.6 VLE of Water -Ammonium Sulphate. . . . . . . . . . . . . . . . . . . . 27
4.7 VLE of Water - Sodium Thiocyanate. . . . . . . . . . . . . . . . . . . . 28
4.8 VLE of Water - Sodium Nitrate. . . . . . . . . . . . . . . . . . . . . . . 28
4.9 VLE of Water - Potassium Nitrate. . . . . . . . . . . . . . . . . . . . . . 29
4.10 VLE of Ammonia - Water - Potassium Acetate in 10 Mass % Ammonia
Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
4.11 VLE of Ammonia - Water - Potassium Acetate in 20 Mass % Ammonia
Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.12 VLE of Ammonia - Water - Potassium Acetate in 30 Mass % Ammonia
Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
4.13 VLE of Ammonia - Water - Copper Acetate in 10 Mass % Ammonia
Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.14 VLE of Ammonia - Water - Copper Acetate in 20 Mass % Ammonia
Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
iii
Thermodynamic Study of Ternary Refrigerant Equilibria
4.15 VLE of Ammonia - Water - Copper Acetate in 30 Mass % Ammonia
Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.16 VLE of Ammonia - Water - Ammonium Sulphate in 10 Mass % Ammo-
nia Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
4.17 VLE of Ammonia-Water-Ammonium Sulphate in 20 Mass % Ammonia
solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.18 VLE of Ammonia - Water - Ammonium Sulphate in 30 Mass % Ammo-
nia Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.19 VLE of Ammonia - Water - SodiumThiocyanate in 10 Mass % Ammonia
Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.20 VLE of Ammonia - Water - SodiumThiocyanate in 20 Mass % Ammonia
Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.21 VLE of Ammonia - Water - SodiumThiocyanate in 30 Mass % Ammonia
Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.22 VLE of Ammonia - Water - Sodium Nitrate in 10 Mass % Ammonia
solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.23 VLE of Ammonia-Water-Sodium Nitrate in 20 Mass % Ammonia Solution. 39
4.24 VLE of Ammonia-Water-Sodium Nitrate in 30 Mass % Ammonia Solution. 39
4.25 VLE of Ammonia - Water - Potassium Nitrate in 10 Mass % Ammonia
Solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.26 VLE of Ammonia - Water - Potassium Nitrate in 20 Mass % Ammonia
Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
4.27 VLE of Ammonia - Water - Potassium Nitrate in 30 Mass % Ammonia
Solution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.28 Parity plot for Bubble Pressure of Water - Potassium Acetate Mixture. . . 45
4.29 Parity plot for Bubble Pressure of Water - Copper Acetate Mixture. . . . . 46
4.30 P/(P
no salt
(1 −x
salt
)) for Water-Potassium Acetate Mixture. . . . . . . . 46
4.31 Parity plot for bubble pressure of Ammonia - Water - Potassium Acetate
Mixture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
iv
Thermodynamic Study of Ternary Refrigerant Equilibria
4.32 Parity plot for Bubble Pressure of Ammonia - Water - Copper Acetate
Mixture. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
4.33 Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at
40
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.34 Calculated Excess Gibbs free Energy of Ammonia - Water - Potassium
Acetate at 40
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
4.35 Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at
60
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.36 Calculated Excess Gibbs Free Energy of Ammonia - Water - Potassium
Acetate at 60
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
4.37 Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at
80
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.38 Calculated Excess Gibbs Free Energy of Ammonia - Water - Potassium
Acetate at 80
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.39 Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at
100
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.40 Calculated Excess Gibbs Free Energy of Ammonia - Water - Potassium
Acetate at 100
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
4.41 P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Potassium Acetate mixture
at 40
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
4.42 P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Potassium Acetate Mixture
at 60
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
4.43 P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Potassium Acetate Mixture
at 80
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
4.44 Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at
40
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.45 Calculated Excess Gibbs Free Energy of Ammonia - Water - Potassium
Acetate at 40
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
v
Thermodynamic Study of Ternary Refrigerant Equilibria
4.46 Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at
60
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.47 Calculated Excess Gibbs Free Energy of Ammonia - Water - Potassium
Acetate at 60
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.48 Calculated Bubble Pressure of Ammonia - Water-Potassium Acetate at
80
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.49 Calculated Excess Gibbs Free Energy of Ammonia - Water - Potassium
Acetate at 80
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4.50 Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at
100
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
4.51 Calculated Excess Gibbs Free Energy of Ammonia - Water - Potassium
Acetate at 100
0
C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
6.1 Calculated mole fraction of Ammonia in vapor phase for Ammonia -
Water - Potassium Acetate at 40
0
C using Redlich - Kister equation. . . . 72
6.2 Calculated mole fraction of Ammonia in vapor phase for Ammonia -
Water - Potassium Acetate at 60
0
C using Redlich - Kister Equation. . . . 72
6.3 Calculated mole fraction of Ammonia in vapor phase for Ammonia -
Water - Potassium Acetate at 80
0
C using Redlich - Kister Equation. . . . 73
6.4 Calculated mole fraction of Ammonia in vapor phase for Ammonia -
Water - Potassium Acetate at 100
0
C using Redlich - Kister Equation. . . 73
6.5 Calculated mole fraction of Ammonia in vapor phase for Ammonia -
Water - Potassium Acetate at 40
0
C using NRTL Equation. . . . . . . . . 74
6.6 Calculated mole fraction of Ammonia in vapor phase for Ammonia -
Water - Potassium Acetate at 60
0
C using NRTL Equation. . . . . . . . . 74
6.7 Calculated mole fraction of Ammonia in vapor phase for Ammonia -
Water - Potassium Acetate at 80
0
C using NRTL Equation. . . . . . . . . 75
6.8 Calculated mole fraction of Ammonia in vapor phase for Ammonia -
Water - Potassium Acetate at 100
0
C using NRTL Equation. . . . . . . . 75
vi
List of Tables
4.1 Redlich-Kister constants for Water - Salt . . . . . . . . . . . . . . . . . . 45
4.2 Redlich-Kister constants for Ammonia - Water - Salt . . . . . . . . . . . 47
4.3 Table showing values of D
0
, D
1
, D
2
, and D
3
at different Temperature
for Ammonia - Water - Potassium Acetate Mixture. . . . . . . . . . . . . 61
4.4 Table showing values of E
0
, E
1
, E
2
, and E
3
at different Temperature for
Ammonia - Water - Potassium Acetate Mixture. . . . . . . . . . . . . . . 61
4.5 Table showing values of D
0
, D
1
, D
2
, and D
3
at different Temperature
for Ammonia - Water - Copper Acetate Mixture. . . . . . . . . . . . . . . 61
4.6 Table showing values of E
0
, E
1
, E
2
, and E
3
at different Temperature for
Ammonia - Water - Copper Acetate Mixture. . . . . . . . . . . . . . . . 62
4.7 Table showing values of D
0
, D
1
and D
2
at different Temperature for
Ammonia - Water - Ammonium Sulphate Mixture. . . . . . . . . . . . . 62
4.8 Table showing values of E
0
, E
1
and E
2
at different Temperature for
Ammonia - Water - Ammonium Sulphate Mixture. . . . . . . . . . . . . 62
4.9 Table showing values of D
0
, D
1
and D
2
at different Temperature for
Ammonia - Water - Sodium Thiocyanate Mixture. . . . . . . . . . . . . . 63
4.10 Table showing values of E
0
, E
1
and E
2
at different Temperature for
Ammonia - Water - Sodium Thiocyanate Mixture. . . . . . . . . . . . . . 63
4.11 Table showing values of D
0
, D
1
and D
2
at different Temperature for
Ammonia - Water - Sodium Nitrate Mixture. . . . . . . . . . . . . . . . . 63
4.12 Table showing values of E
0
, E
1
and E
2
at different Temperature for
Ammonia - Water - Sodium Nitrate Mixture. . . . . . . . . . . . . . . . . 64
vii
Thermodynamic Study of Ternary Refrigerant Equilibria
4.13 Table showing values of D
0
and D
1
at different Temperature for Ammo-
nia - Water - Potassium Nitrate Mixture. . . . . . . . . . . . . . . . . . . 64
4.14 Table showing values of E
0
and E
1
at different Temperature for Ammo-
nia - Water - Potassium Nitrate Mixture. . . . . . . . . . . . . . . . . . . 64
6.1 P/(P
no salt
(1 −x
salt
)) for Water - Potassium Acetate Mixture. . . . . . . . 76
6.2 P/(P
no salt
(1 −x
salt
)) for Water- Copper Acetate Mixture. . . . . . . . . 76
6.3 P /( P
no salt
(1 −x
salt
) ) for Water - Ammonium Sulphate Mixture. . . . 76
6.4 P/(P
no salt
(1 −x
salt
)) for Water - Sodium Thiocyanate Mixture. . . . . . 77
6.5 P/(P
no salt
(1 −x
salt
)) for Water - Sodium Nitrate Mixture. . . . . . . . . 77
6.6 P/(P
no salt
(1 −x
salt
)) for Water - Potassium Nitrate mixture. . . . . . . . 77
6.7 P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Potassium Acetate Mixture
in 30 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . . . . . 78
6.8 P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Potassium Acetate mixture
in 20 Mass % Ammonia solution. . . . . . . . . . . . . . . . . . . . . . . 78
6.9 P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Potassium Acetate Mixture
in 10 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . . . . . 78
6.10 P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Copper Acetate Mixture in
30 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . . . . . . . 79
6.11 P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Copper Acetate Mixture in
20 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . . . . . . . 79
6.12 P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Copper Acetate Mixture in
10 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . . . . . . . 79
6.13 P/ (P
no salt
(1 − x
salt
)) for Ammonia - Water - Ammonium Sulphate
Mixture in 30 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . 80
6.14 P/ (P
no salt
(1 − x
salt
) ) for Ammonia - Water - Ammonium Sulphate
Mixture in 20 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . 80
6.15 P/( P
no salt
(1 − x
salt
)) for Ammonia - Water - Ammonium Sulphate
Mixture in 10 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . 80
viii
Thermodynamic Study of Ternary Refrigerant Equilibria
6.16 P/ (P
no salt
(1 − x
salt
)) for Ammonia - Water - Sodium Thiocyanate
Mixture in 30 Mass % of Ammonia Solution. . . . . . . . . . . . . . . . 81
6.17 P/ (P
no salt
(1 − x
salt
)) for Ammonia - Water - Sodium Thiocyanate
Mixture in 20 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . 81
6.18 P/ ( P
no salt
(1 − x
salt
) ) for Ammonia - Water - Sodium Thiocyanate
Mixture in 10 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . 81
6.19 P/(P
no salt
(1 − x
salt
)) for Ammonia - water - Sodium Nitrate Mixture in
30 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . . . . . . . 82
6.20 P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Sodium Nitrate Mixture in
20 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . . . . . . . 82
6.21 P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Sodium Nitrate Mixture in
10 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . . . . . . . 82
6.22 P/(P
no salt
(1 − x
salt
)) for Ammonia - Water - Potassium Nitrate Mixture
in 30 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . . . . . 83
6.23 P/(P
no salt
(1 − x
salt
)) for Ammonia - Water - Potassium Nitrate Mixture
in 20 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . . . . . 83
6.24 P/(P
no salt
(1 − x
salt
)) for Ammonia - Water - Potassium Nitrate Mixture
in 10 Mass % Ammonia Solution. . . . . . . . . . . . . . . . . . . . . . 83
ix
Chapter 1
Introduction
1
Thermodynamic Study of Ternary Refrigerant Equilibria
1.1 Introduction
Interest in absorption refrigeration systems driven by waste heat, as an alternative to
conventional power-driven systems has increased because of current energy and envi-
ronmental issues. The working fluids commercially used in the absorption refrigeration
system and heat pumps are water - lithium bromide and ammonia - water. Ammonia-
water system is well known absorption refrigeration working fluid which is widely used
in the industries in ammonia absorption refrigeration cycle for the generation of refriger-
ation. The standard Ammonia Absorption Refrigeration (AAR) cycle operates at a heat
source of 120 to 140
0
C. A significant amount of industrial waste heat is below 100
0
C
and can be made available for refrigeration. AAR cycle needs to be modified to run it
using low grade heat source. One of the ways to modify the AAR cycle is to change the
vapor-liquid equilibrium (VLE) of ammonia-water binary system.
H
2
O−LiBr operate under high vacuum conditions hence, H
2
O−LiBr are volumi-
nous and require air removal systems, do not operate belowan evaporation temperature of
4
0
C and crystallization and corrosion problems. However, the ammonia - water system
needs rectification of the refrigerant vapor, operates at high pressure, high water content
in the vapor phase, resulting in, a necessary requirement for an expensive dephlegmator,
and resulting in the high vapor pressure at elevated temperature for the NH
3
−H
2
O and
therefore requires resistant and heavy components [Salavera et al. , 2005]. However, this
system can be air-cooled and can operate at evaporator temperatures below 0
0
C.
Knowledge of salt effect is necessary in separation processes such as extractive dis-
tillation, azeotropic distillation, extractive crystallisation, biofluid processing, geological
formations and many such processes. These processes involve non-volatile salts, arise in
two situations. First, as an alternative to extractive or azeotropic distillation, salts may
be added to a system to alter the VLE behavior. Second, there are cases where salt is
generated in the process before final product purification [Boone et al. , 1976].
The addition of salt to any binary or multicomponent system may change the VLE of
system by changing the relative volatility, solubility, thermal conductivity, density, sur-
face tension and partial pressure etc. of the solvents because of the interactions between
2
Thermodynamic Study of Ternary Refrigerant Equilibria
the salt ions and solvent components [Lee, 1997; Darwish and Al-Anbar, 1997]. These
changes, if they occur, will result in altering the VLE of the system [Johnson and Furter,
1957; Darwish and Al-Anbar, 1997]. VLE of ammonia-water system can be effectively
changed by using the additives like NaOH and KOH [Brass et al. , 2000; Salavera et al.
, 2005], LiBr [Peters et al. , 1994] and LiNO
3
[Libotean et al. , 2007]. The VLE data
available for ammonia-water-salt systems is inadequate. A study of the effect of various
salts on the VLE of ammonia-water system was therefore undertaken to suggest changes
in the binary ammonia-water system.
Decrease in the solubility of a non-electrolyte in the solvent caused by the addition
of a salt is called as salting-out effect and the opposite is called as salting-in effect. Both
these effects is useful in AAR cycle. The salting-out salts will be useful in the generator
where the vapor pressure of ammonia can be increased and salting-in salts will be useful
in the absorber where the solubility of ammonia in water will be enhanced. The addition
of salting-out salt in the generator of AAR system will significantly increase the vapor
pressure of the system by reducing the solubility of ammonia in water. This salt will be
carried into absorber along with the weak solution from the bottom of the generator. The
presence of salting-out salt in the absorber of AAR cycle, will have adverse effect on its
performance. Hence we need to restrict the salt in the generator side. This can be done by
using membrane separation process and the pressure gradient between the generator and
absorber can be utilised for the said separation of salt from the ammonia-water mixture.
The pressure required for the separation of the salt, using membrane separation technique
will depend on the size of the salt molecule. Smaller the size of the molecule, higher the
pressure required for the separation. The presence of salt may cause corrosion problems
to the equipment and hence we may have to spend more capital investment for having
equipments made up of corrosion resistant material. Considering all the above mentioned
things, the criterion for the selection of salts to be tested on the VLE of ammonia-water
mixture was decided on the basis of its solubility in ammonia and water, its molecular
size and its corrosivity.
The salts were selected on the basis of their solubility in water and ammonia inde-
3
Thermodynamic Study of Ternary Refrigerant Equilibria
pendently. If a salt is more soluble in water than in ammonia, then it will show more
interaction with water than with ammonia and hence the resulting effect will be salting-
out of ammonia. Similarly, if a salt is more soluble in ammonia than in water or if salt
is soluble in both ammonia and water, then it will show interaction with both and the
resulting effect will be salting-in.
Salting-in or salting-out effect are considerable industrial and theoretical importance.
It is observed that, the molecules of the more polar component are generally preferentially
attracted by the electrostatic field of the ions and hence the vapor composition is enriched
by the less polar solvent in which the salt is less soluble [Iliuta et al. , 1998]. On the
addition of salt to the binary system, if the total vapor pressure of the system increases
then it is called as salting-out effect and if the total vapor pressure of the system decreases
then it is called as salting-in effect.
The performance of AAR cycle can be improved by adding salt, which either in-
creases or decreases the solubility of ammonia in water. In tropical conditions like India
where both the condenser and absorber are operated at a temperature of around 40
0
C,
the use of low temperature heat sources is more difficult. If we want to run a standard
AAR cycle at a heat source of around 70−100
0
C, we need to add salting-out salt which
will give same vapor pressure in the generator as it gives at 120 − 140
0
C without salt.
We need such a salt, which shows salting-out effect at 70 − 100
0
C and salting-in at 40
0
C or at least no effect or very less salting-out effect at 40
0
C. So that the overall effect
of salt on the AAR cycle will be positive and there will not be any need to restrict the salt
up to the generator side.
Very few additives are tested on the VLE of ammonia-water system. Therefore the
study of ammonia-water VLE with different additives is important to suggest the changes
in the binary ammonia-water system.
The different additives studied includes potassium acetate, copper acetate, ammo-
nium sulphate, sodium thiocynate, sodium nitrate and potassium nitrate. All these addi-
tives were tested at ammonia concentration of 10, 20 and 30 mass% {mass of ammonia
/ (mass of ammonia + mass of water)} and at different concentrations of additives. PTx
4
Thermodynamic Study of Ternary Refrigerant Equilibria
data was generated for these systems. Rocked static VLE cell was used to generate the
VLE data for ammonia-water systemwith additive. The salt concentration used in mass%
and is given as
Salt mass concentration =
mass of salt
mass of salt +mass of ammonia +mass of water
×100
The generated VLE data for ammonia-water-salt system was correlated using the
Redlich-Kister and NRTL equation.
1.2 Refrigeration
Maintaining the temperature below that of the surrounding is called as refrigeration. It
is the process of removal of heat from low temperature and rejecting it at higher tem-
perature. This process is opposite to the natural direction of heat flow. Second Law of
thermodynamics states that heat can not be transferred from low temperature to higher
temperature without expenditure of energy. Refrigeration is best known for its appli-
cations in air conditioning and in the treatment, transportation and preservation of food
and beverages. It also finds large scale industrial applications in manufacturing of ice
and dehydration of gases. Application in the petroleum industry includes in lubricating
oil purification, low temperature reactions and separation of volatile hydrocarbons. Gas
liquefaction process also requires large scale refrigeration. Generation of refrigeration
below the temperature of -150
0
C is called as cryogenics.
Types of Refrigeration Cycles
There are number of refrigeration techniques and their combinations, that can generate
cold condition for domestic and industrial applications. Vapor compression (mechanical)
refrigeration cycle and Vapor absorption refrigeration cycle are the most widely used.
The main difference between the two cycle is the type of energy source used for produc-
5
Thermodynamic Study of Ternary Refrigerant Equilibria
tion of refrigeration. Vapor Compression cycle needs mechanical work as energy input
while vapor absorption refrigeration cycle is a heat operated refrigeration cycle.
1.2.1 Vapor Compression Refrigeration
Currently, electric motor driven vapor compression refrigeration cycles dominate the air
conditioning and refrigeration applications. Figure 1.1 shows the block diagram for a
Vapor Compression Refrigeration cycle. The four basic components of the system are
the compressor, condenser, evaporator and expansion valve.
1
2
Evaporator
Compressor
3 4
Throttle
Valve
Condenser
Figure 1.1: Block Diagram of Vapor Compression Refrigeration system.
A working Fluid (refrigerant) is boiled off in the evaporator at pressure, low enough
to provide the cooling. A work driven compressor (usually electrical work) then increases
the pressure of the evaporated working fluid. The high pressure vapors are condensed in
the condenser by rejecting heat to the surrounding. The condensed working fluid is then
expanded back into the evaporator, (via an expansion valve) where it can again provide
the cooling. The cycle involves two pressures, high and low, to enable continuous process
to produce the cooling effect.
6
Thermodynamic Study of Ternary Refrigerant Equilibria
1.2.2 Vapor Absorption Refrigeration
The heat operated vapor absorption refrigeration technique employs a solute gas as the
vaporizing refrigerant and a suitable solvent for recovering and recycling the refrigerant.
Figure 1.2 shows the block diagram of Vapor absorption refrigeration cycle. The refriger-
ant is vaporized in the evaporator at low pressure to provide the cooling. The evaporated
refrigerant is absorbed in solvent liquid (absorbent) in the absorber. The heat of solution
released in the absorber is removed by cooling water. The rich solution produced in the
absorber is separated by application of heat in the generator. The refrigerant is boiled
off, producing a lean solution which is recycled to the absorber. The vapors from the
generator are condensed and returned as refrigerant liquid to the evaporator. The cycle
involves two pressures, high pressure side (Generator and condenser) and low pressure
side (absorber and evaporator). Refrigerant solution from the absorber is pumped to the
generator, where the absorption refrigeration cycle requires electrical energy. However,
the electricity required is much less compared to the heat required.
A large number of refrigerant-solvent combinations can produce refrigeration by ab-
sorption refrigeration technique. Some of the industrially important solute-solvent com-
binations are;
• Ammonia as refrigerant and Water or dilute aqueous solution of Ammonia as ab-
sorbent.
• Water as the refrigerant and aqueous Lithium Bromide solution as absorbent.
Ammonia-water system is advantageous when compared to the water-lithium bromide
because the later can not operate below freezing point of water.
7
Thermodynamic Study of Ternary Refrigerant Equilibria
Condenser
Generator
Evaporator
Absorber
Q
B
Q
C
Q
E
Q
A
Reflux
Top product
Feed
weak aqua
Refrigerant
Evaporated Refrigerant
Figure 1.2: Block Diagram of Vapor Absorption Refrigeration system.
1.3 Ammonia - Water Mixture
Ammonia and ammonia-water mixtures attract more attention to the usage as natural
refrigerant, supercritical fluid solvent and working medium in power cycles and refriger-
ation cycle. Power cycles with ammonia-water mixtures as working fluids have been
shown to reach higher thermal efficiencies than the traditional steam turbine (Rank-
ine) cycle with water as the working fluid. Ammonia is highly soluble in water. Its
high solubility is because of the hydrogen bond formation between water and ammo-
nia. While these bonds, are not exactly sharing electrons like Covalent bonding. The
hydrogen bond is an electrostatic force between covalently bonded hydrogen atom of
one molecule and electronegative atom of another molecule. It is very week (strength
about 2-10 Kcal/mole) as compared to a covalent bond (strength 50-100 Kcal/mole).
The hydrogen bonding between water molecules is stroger as compaired to the hydrogen
bonding between ammonia molecules. This is the main reason, why water is liquid and
ammonia is gas at room temperature. Comparison of the physical properties of the am-
monia with that of water shows that ammonia has the lower melting point, boiling point,
density, viscosity, dielectric constant and electrical conductivity; This is due to weaker
8
Thermodynamic Study of Ternary Refrigerant Equilibria
H-bonding in ammonia.
Water and ammonia are natural fluids which do not harm the environment. There-
fore, they are also considered as an alternative refrigerant to replace chlorofluorocarbons
in some refrigeration applications. For design, simulation and optimization of such ma-
chinery, accurate description of the thermodynamic properties of the mixture for a wide
range of pressure, temperature and composition are needed. For this purpose, correla-
tions for calculating thermodynamic properties of binary mixtures have been presented
by researchers.
1.4 Objective of the Work
1. The first objective is to measure a set of pressure-temperature-total composition
data.
2. To study the influence of salt concentration on the vapor-liquid equilibrium behav-
ior of ammonia-water and to develop a fundamentally sound approach to correlat-
ing the influence of salt on the behavior of a system.
3. To estimate activity coefficients of the solvents from experimental data correlated
using Redlich-Kister and NRTL equations.
9
Chapter 2
Literature Survey
10
Thermodynamic Study of Ternary Refrigerant Equilibria
2.1 Literature Survey for Ammonia - Water System
The NH
3
−H
2
O mixture is receiving increasing attention due to the potential use of the
systemas a working fluid in refrigeration and power cycles. The binary NH
3
−H
2
O mix-
ture has a large technical significance in the fields of absorption refrigeration machines,
absorption heat pumps and heat transformers. Ammonia and water have been considered
as alternative organic refrigerants to replace chlorofluorocarbons (CFC) in some refriger-
ation applications to prevent the destruction of environment and natural working fluids.
NH
3
−H
2
O mixture does not affect the atmospheric ozone layer nor do they contribute
to the green house effect. Therefore, the significance of this mixture in refrigeration
technology is strongly increasing. Refrigerating cycle with NH
3
− H
2
O mixtures as
working fluids to reach higher coefficient of performance than traditional working flu-
ids. Thermodynamic modeling of a technological processes requires information on the
phase equilibrium and other thermodynamic properties of the NH
3
−H
2
O mixtures.
The first attempt to obtain the VLE data on the ammonia-water system over the full
range of composition was made by Wilson, who measured the total vapor pressure VLE
data from 273.15 K to 364.15 K and up to 1.17 MPa. His study was further extrapolated
to 3.85 Mpa. Isobaric VLE of the system NH
3
− H
2
O are experimentally determined
at 14.69 and 65 psia in dilute solution of ammonia in water. The results obtained are
correlated in terms of the relative volatility [Polak et al. , 1975].
Vapor-liquid equilibrium data for the ammonia-water system over the complete com-
position range have been obtained at the temperature from 313.15 K and 588.7 K [Gille-
spie et al. , 1987]. The total pressure method is used to obtain PTx data, and in a separate
procedure equilibriumvapor and liquid phase composition (PTxy data) are analyzed. The
PTx data is reduced to PTxy data using the Redlich - Kister activity coefficient expan-
sion with four parameter. The parameter of the Redlich-Kister expansion is obtained
by fitting the total pressure data using a least squares procedure. One PTxy is used to
evaluate the second cross virial coefficient. Relative volatility is calculated from the the
total pressure data, which are in good agreement with the values obtained from equilib-
rium phase measurements. The reduced data thus obtained is in good agreement with
11
Thermodynamic Study of Ternary Refrigerant Equilibria
the actual PTxy measurement, giving a thermodynamically consistant set of vapor-liquid
equilibrium measurements.
Syed et al. have measured the Isothermal vapor-liquid equilibriumdata for the ammonia-
water system at temperatures from 306 to 618 K and at pressures up to 22 MPa [Syed
et al. , 1987]. The equilibrium temperatures, pressures, and the compositions of both liq-
uid and vapor phases are measured simultaneously and compaired results with literature.
The data is extended into the critical regions of the seven-phase envelopes at temperatures
between the critical points of ammonia and water.
Pressure-temperature-overall composition VLE data are determined for the ammonia-
water system at five temperatures between 293.15 and 413.15 K and up to 500 psia
[Smolen et al. , 1991]. The measured data is correlated by means of Redlich-Kwong
equation of state modified to include Peneloux’s volume translation and a density-dependent
mixing rule. Different constants values in the vapor and liquid phases have used to achive
calculated vapor-phase composition with previous literature result.
The experimental data on phase equilibria in ammonia-water mixture are fitted on
basis of thermodynamic perturbation theory in the range of temperature (200 - 640 K)
and pressure (0.02 - 23 MPa) [Abovsky, 1996]. Data for the vapor-liquid equilibrium are
regressed by least square method. Effects of mixing on enthalpy and volume and some
deviations from one-fluid approximation is analyzed.
Mejbri et al. have model the ammonia-water refrigerant mixture by three different
approaches and compared with model [Mejbri and Bellagi, 2005]. The first is an empiri-
cal approach based on a free enthalpy model of the mixture considered as resultant of the
properties of its pure components and of an excess term corresponding to the deviation
to ideal solution concept. Secondly, a semi-empirical approach based on the PATEL and
TEJA cubic equation of state is considered. Finally, a theoretical approach formulated as
PC-SAFT (perturbed chain statistical associating fluid theory) equation of state is treated.
Comparison of these three methods proves the superiority of PC-SAFT in predicting and
extrapolating the thermodynamic properties of the water-ammonia systemup to very high
temperatures and pressures.
12
Thermodynamic Study of Ternary Refrigerant Equilibria
The PVTx properties of NH
3
− H
2
O mixture have been measured in the near and
supercritical regions. Measurements are made at temperatures from 301 to 634 K and
at pressures up to 28 MPa [Polikhronidi et al. , 2009]. Temperatures and densities at
the liquid-gas phase transition curve, dew and bubble-pressure points, and the critical
parameters for the NH
3
−H
2
O mixture are obtained using the quasi-static thermograms
and isochoric break-point techniques.
2.2 Literature Survey for Ammonia - Water - Salt Sys-
tem
Vapor-liquid equilibriumdata for the systemammonia - water and lithiumbromide (LiBr)
at four temperatures, 303.15, 333.15, 373.15 and 423.15 K and pressures up to 1.5 MPa.
The salt concentration in the liquid phase was chosen in the range 5-60 mass % LiBr in
pure water [Peters et al. , 1994]. Similar type of experiments has done by Zimmermann
(1989) in the temperature range of 303 K to 423 K and pressures up to 15 bar [Zimmer-
mann and Keller, 1989]. The analysis of the data obtained for the two binary mixtures
ammonia-water and water- lithium bromide indicates, the static method to be useful to
measure VLE in the NH
3
−H
2
0 −LiBr system.
Boone et al. have explained the procedure for correlating the effect of non-volatile
salts on the vapor-liquid equilibrium of binary solvents [Boone et al. , 1976]. The pro-
cedure is based on estimating the influence of salt concentration of both components in
a pseudo-binary solution. Using this technique and Wilson parameter have determined
from the infinite dilution activity coefficients, precise estimation of bubble point temper-
ature and vapor phase composition is obtained over a range of salt and solvent composi-
tion.
Data for a number of alcohol-water systemsaturated with various inorganic salts have
been correlated by computing pseudo-activity coefficients for the volatile components
[Rousseau et al. , 1972]. Coefficient computed are readily correlated by means of the
Van-laar, Wilson and Renon equations.
13
Thermodynamic Study of Ternary Refrigerant Equilibria
A static method is used to obtain vapor liquid equilibrium data for the systems am-
monia - water - potassium hydroxide and ammonia - water - sodium hydroxide at tem-
peratures of 303 and 318 K and pressures from 0.1 to 1.3 MPa [Brass et al. , 2000]. The
salt concentration in the liquid phase is chosen in the range from 2 to 60 mass % salt in
water. In both systems NH
3
− H
2
O − NaOH and NH
3
− H
2
O − KOH, solid liquid
vapor equilibriumare observed. In the NH
3
−H
2
O−KOH system, liquid - liquid vapor
equilibrium is observed at 318 K and 1.1 MPa.
An equilibrium cell is used to measure thermal property of the ternary NH
3
−H
2
O−
LiBr mixtures. The pressure and temperature data for their VLE data are measured at
ten temperature points between 15-85
0
C, and pressures up to 2 MPa [Yuyuan and Tiehui,
2005]. The LiBr concentration of the solution is chosen in the range of 5-60% of mass
ratio of LiBr in pure water and ammonia concentration up to 0-60%. The VLE for the
NH
3
− H
2
O − LiBr ternary solution is measured statically. The experimental results
show that the equilibrium pressures reduced by 30-50%, and the amount of component
of water in the gas phase reduced greatly to 2.5% at 70
0
C temperature.
Vapor-liquid equilibrium of ammonia - water - potassium hydroxide and ammonia -
water - sodium hydroxide systems are measured by a static method from 293.15 K to
353.15 K. The experimental vapor pressure data has been correlated with temperature
and mass percent concentration using an analytical polynomial equation [Salavera et al.
, 2005].
The vapor pressure of ammonia - lithium nitrate - water and ammonia - lithium ni-
trate mixtures is measured by a static method from 293.15 K to 353.15 K in ammonia
mass fractions ranging from 0.2 to 0.6 [Libotean et al. , 2007]. The equilibrium liquid
and vapor compositions are determined using the Redlich-Kister equation for activity co-
efficients of the liquid phase and the Redlich-Kwong equation of state for the modeling
the vapor phase nonideality. Vapor pressure, Temperature and liquid-phase composition
are correlated using an empirical equation. The capability of the electrolyte nonrandom
two liquid (E-NRTL) model to predict the VLE of the ternary mixture is evaluated by
comparing predicted and experimental data of the ammonia - lithium nitrate - water so-
14
Thermodynamic Study of Ternary Refrigerant Equilibria
lutions. The binary interaction parameters of ammonia - lithium nitrate needed for the
prediction of ternary VLE are determined from binary experimental data. The isobaric
data for the system methanol-water, ethanol-water and 1-propanol water, each saturated
with a inorganic salts is correlated by means of the Van-laar, Wilson and Renon equations
[Rousseau et al. , 1972]. Activity coefficients are calculated for each volatile component
using standard equation state for thermodynamic equilibrium.
The simultaneous solubility of sulfur dioxide and ammonia in aqueous solutions of
(ammonium sulfate or sodium sulfate) is measured by a synthetic method in the tempera-
ture range from 313.6 K to 373.2 K and at pressures up to 2.5 MPa [Meyer et al. , 2006].
The enthalpy change upon diluting aqueous solutions of sulfur dioxide, ammonia and
(ammonium sulfate or sodium sulfate) in aqueous solutions of the same salt is measured
in a batch calorimeter at about 313 K and 352 K. The experimental results are compaired
with predictions from a thermodynamic model for the vapor-liquid equilibrium and the
enthalpy of dilution of those chemical reacting systems. In that model, activity coeffi-
cients are calculated from Pitzer’s modality-scale-based Gibbs excess energy model.
15
Chapter 3
VLE of Ammonia - Water System
16
Thermodynamic Study of Ternary Refrigerant Equilibria
Vapor-liquid equilibrium, is a condition where a liquid and its vapor (gas phase) are
in equilibrium with each other, a condition or state where the rate of evaporation (liq-
uid changing to vapor) equals the rate of condensation (vapor changing to liquid) on a
molecular level such that there is no net (overall) vapor-liquid interconversion. Although
in theory equilibrium takes forever to reach, such an equilibrium is practically reached
in a relatively closed location if a liquid and its vapor are allowed to stand in contact
with each other long enough with no interference or only gradual interference from the
outside. Vapor-liquid equilibrium is at the heart of many chemical and envirmental en-
gineering processes and activities. Distillation, drying and evaporation are all based on
VLE. For ideal solution, it is simple and we can separate any mixture of species with
different boiling points. For nonideal solution, the process is more complex, specially in
the case of ammonia-water mixture.
3.1 VLEEquations for Ammonia - Water Binary System
The starting point is the equality of the fugacity of each species in the two phases:
ˆ
f
i
V
=
ˆ
f
L
i
i = 1, 2, · · · · · · · · · · · · , N
where for the N-component mixture
ˆ
f
i
V
is the fugacity of the component i in the vapor
phase and
ˆ
f
L
i
is the fugacity of component i in the liquid phase. In the activity coefficient
approach the vapor-liquid equilibrium of ammonia-water system was calculated by using
the equation,
P
´
φ
i
y
i
= x
i
γ
i
P
sat
i
φ
sat
i
exp

V
L
i
(P
i
−P
sat
i
)
RT

(3.1)
Component 1: Ammonia
Component 2: Water
Correlation for calculating saturated temperature and saturated pressure of ammonia
and water are given as,
17
Thermodynamic Study of Ternary Refrigerant Equilibria
For Ammonia,
log P
sat
1
= 7.36048 −
926.13
T
sat
1
+ 240.17
(3.2)
For Water,
log P
sat
2
= 8.07131 −
1760.63
T
sat
2
−233.426
(3.3)
where P
sat
1
and P
sat
2
are in mm Hg and T
sat
1
and T
sat
2
are in
0
C
Equation of state analogous to Redlich-Kwong equation of state has been used, how-
ever, it also includes 2
nd
and 3
rd
virial coefficients [Gillespie et al. , 1987].
Z =
V
V −b
+
B −b
V
+
C −b
2
V
2
(3.4)
where,
V molar volume
b,B,C Virial Coefficients
b is the Redlich-Kwong b, given as:
b = y
1
b
1
+y
2
b
2
(3.5)
where,
b
1
= 21.11 and b
2
= 15.0
Second Virial Coefficient (B):
B = y
2
1
B
11
+ 2y
1
y
2
B
12
+y
2
2
B
22
(3.6)
where,
B
11
= 18.02
¸
1.898 −

2641.62
T

exp

186210
T
2

(3.7)
18
Thermodynamic Study of Ternary Refrigerant Equilibria
B
22
= 0.926
¸
26.35 −27.93

exp

725
T

−1.0

(3.8)
B
12
=
1
2
¸
B

11

V
c2
V
c1

+B

22

V
c1
V
c2

(3.9)
V
c1
and V
c2
are critical volumes of water and ammonia respectively,
V
c1
= 56 cc/mol
V
c2
= 72.5 cc/mol
Here, B

11
means B
11
calculated from Eqn. 3.7, substituting
A
12
T
for
1
T
. Similarly for
B

12
A
12
= 0.944 + 0.0138

1000
T

2
T < 405.9K
= 1.015 T ≥ 405.9K
Third Virial Coefficient (C):
C = y
3
1
C
111
+ 3y
2
1
y
2
C
112
+ 3y
1
y
2
2
C
122
+y
3
2
C
222
(3.10)
where,
C
111
= 2097 (cc/mol)
2
C
222
= 4178 (cc/mol)
2
3C
112
= 2

V
c2
V
c1

C
111
+

V
c1
V
c2

2
C
222
3C
122
= 2

V
c1
V
c2

C
222
+

V
c2
V
c1

2
C
111
Fugacities of Pure Species
Fugacity Coefficient of Pure Species,
Fugacity coefficient of pure species can be calculated by,
19
Thermodynamic Study of Ternary Refrigerant Equilibria
ln φ
i
=
1
RT

V


RT
V
−P

dV −lnZ + (Z −1) (3.11)
ln φ
i
=

V

(1 −Z)
dV
V
−ln Z + (Z −1)
substituting Z from Eqn. 3.4 in above Equation,
ln φ
i
= ln

V
V −b

+
B −b
V
+
2 (C −b
2
)
V
2
−ln Z +Z −1 (3.12)
Fugacity Coefficient of Pure Species in a Solution,
ln
´
φ
i
=
1
RT

V

¸
RT
V
−N

∂P
∂N
i

T,V,N
j
¸
dV −ln Z (3.13)
For ammonia,
ln
´
φ
1
= (M
1
+M
2
+M
3
+M
4
) −ln Z (3.14)
where,
M
1
= log

V
V −b

M
2
=
b
2
V −b
M
3
=
−(b +b
2
−2 (y
2
B
22
+y
1
B
12
))
V
T
4A
= 3y
2
2
C
222
+ 2y
1
y
2
C
122F
+y
2
1
C
112F
M
4
=
−(b
2
+ 2bb
2
−T
4A
)
2V
2
For Water,
20
Thermodynamic Study of Ternary Refrigerant Equilibria
ln
´
φ
2
= [M
1
+M
2
+M
3
+M
4
] −ln Z (3.15)
M
1
= log

V
V −b

M
2
=
b
1
V −b
M
3
=
−(b +b
1
−2 (y
1
B
11
+y
2
B
12
))
V
M
4A
= 3y
2
1
C
111
+ 2y
1
y
2
C
112F
+y
2
2
C
122F
M
4
=
(b
2
+ 2bb
1
−M
4A
)
2V
2
where,
C
111
= 2097 (cc/mol)
2
C
222
= 4178 (cc/mol)
2
3C
112
= 2

V
c2
V
c1

C
111
+

V
c1
V
c2

2
C
222
3C
122
= 2

V
c1
V
c2

C
222
+

V
c2
V
c1

2
C
111
21
Chapter 4
VLE Measurements of Ammonia -
Water - Salt System
22
Thermodynamic Study of Ternary Refrigerant Equilibria
4.1 Experimental Set up
The use of rocket cell for ammonia-water system to study their equilibrium total vapor
pressure at varying temperature was initially measured by Gillespie et al. [Gillespie et al.
, 1987]. Similar type of setup with special arrangement of horizontal autoclave rotation
as shown in figure 4.1 was used for further research work. The volume of the autoclave
was 300 cm
3
and the material of construction was SS 316. The digital pressure indicator
(Wika, Mumbai) with an accuracy of ±0.25% was mounted on top of autoclave. The
autoclave has an arrangement for RTD sensor Pt 100 at the center. Temperature was
controlled and measured using a PID controller with an accuracy of 0.1
0
C. Autoclave
was kept on oscillation, to attain better mixing and vapor-liquid phase equilibrium. The
oscillator stand was pivoted to motor with a rod connecting the flywheel which rotates
the autoclave to forward and backward direction.
T
P
M
G
F
H
A
PS
TS
C
B
Figure 4.1: Block Diagram of Vapor-Liquid Equilibrium set up.
(A, B = sampling tube; F = Flange; G = Gear box; T =Temperature indicator; PS =Pres-
sure sensor; M = Motor; H = Casing containing heating coil; TS = Temperature sensor;
V = Autoclave)
23
Thermodynamic Study of Ternary Refrigerant Equilibria
4.2 Materials
Ammonia solution (sp. gravity 0.89, 30% AR solution), potassium acetate (AR grade,
99.0% purity), and copper acetate (AR grade, 99% purity), ammonium sulphate (AR
grade, 99% purity), sodium thiocyanate (LR grade, 98% purity), sodium nitrate (AR
grade, 99.5%) and potassium nitrate (AR grade, 99.5% purity) were used for experimen-
tal work. All chemicals were purchased from M/S sd fine Chemicals Ltd Mumbai.
4.3 System Details
The vapor liquid equilibrium of ammonia-water mixture and water-ammonia-salt were
studied in 10K steps at varying temperature from 313.15 K to 403.15 K. Every set of
experiment were carried out for 45 minutes to attain equilibrium. The effect of differ-
ent concentration of salt additives on ammonia-water system was studied, as their small
presence in system exerts a significant effect on the relative volatility of the component.
Therefor the effect of salt on the VLE of ammonia-water system was studied at different
concentrations. The different salt additives as potassium acetate, copper acetate, ammo-
nium sulphate, sodium thiocyanate, sodium nitrate and potassium nitrate at concentration
of 5, 10, 15 and 20 mass % was added to the mixture of water and ammonia at the con-
centration of 10, 20 and 30 mass% to study the ammonia-water-salt VLE system. Rocked
static VLE cell was used to generate the VLE data for ammonia-water system with addi-
tive.
4.4 Result and Discussion
Aim of the present research work, is to correlate the vapor pressure values obtained from
experimental data with Redlich-Kister and NRTL equations. VLE setup was calibrated
by using pure water, the obtained experimental vapor pressure values matches with the
literature values with 2% difference, as shown in figure 4.2.
24
Thermodynamic Study of Ternary Refrigerant Equilibria
90 100 110 120 130 140 150 160 170 180
Temperature
0
C
0
1
2
3
4
5
6
7
8
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Antonie Equation
Experimetal
Figure 4.2: Vapor-Liquid equilibrium of Pure Water System.
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
o
C
0
3
6
9
12
15
18
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Pure water
10 Mass% Ammonia
20 Mass% Ammonia
30 Mass% Ammonia
Antoine Equation for Water
Gillespie et al.
Figure 4.3: Vapor-Liquid Equilibrium of Ammonia - Water System.
Vapor-liquid equilibrium data for the ammonia-water system over 10, 20 and 30
mass% composition, it had been obtained at the temperature from 313.15 K and 413.15
25
Thermodynamic Study of Ternary Refrigerant Equilibria
K. The total vapor pressure values at the same temperature, was found around 5% differ-
ence, which is in good agreement with the reported data [Gillespie et al. , 1987] as shown
in figure 4.3.
4.5 VLE of Water - Salt Binary Mixture
In the present study, the VLE of water-salt binary mixture was also studied using six dif-
ferent salt. The effect of potassium acetate, copper acetate, ammonium sulphate, sodium
thiocyanate, sodium nitrate and potassium nitrate on the VLE of water was studied at 5,
10 and 15 mass%. It was found that the addition of salt reduces the total vapor pressure
of system.
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
0
C
0
0.5
1
1.5
2
2.5
3
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Antonie Equation
Pure Water
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
Figure 4.4: VLE of Water - Potassium Acetate.
26
Thermodynamic Study of Ternary Refrigerant Equilibria
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
0
C
0
0.5
1
1.5
2
2.5
3
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Antonie Equation
Pure Water
5 Mass% (CH
3
COO)
2
Cu
10 Mass% (CH
3
COO)
2
Cu
15 Mass% (CH
3
COO)
2
Cu
Figure 4.5: VLE of Water - Copper Acetate.
It was observed that the addition of potassium acetate showed maximum reduction in
the total vapor pressure of system as compaired to copper acetate, due to high solubility
of potassium acetate in water. The total vapor pressure of water - potassium acetate and
water - copper acetate with salt concentration is shown in figure 4.4 and 4.5 respectively.
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
0
C
0
0.5
1
1.5
2
2.5
3
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Antonie Equation
Pure water
5 Mass% (NH
4
)
2
SO
4
10 Mass% (NH
4
)
2
SO
4
15 Mass% (NH
4
)
2
SO
4
Figure 4.6: VLE of Water -Ammonium Sulphate.
27
Thermodynamic Study of Ternary Refrigerant Equilibria
30 40 50 60 70 80 90 100 110 120
Temperature
0
C
0
0.25
0.5
0.75
1
1.25
1.5
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Antonie Equation
Pure Water
5 Mass% NaSCN
10 Mass% NaSCN
Figure 4.7: VLE of Water - Sodium Thiocyanate.
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
0
C
0
0.5
1
1.5
2
2.5
3
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Antonie Equation
Pure water
5 Mass% NaNO
3
10 Mass% NaNO
3
Figure 4.8: VLE of Water - Sodium Nitrate.
28
Thermodynamic Study of Ternary Refrigerant Equilibria
30 40 50 60 70 80 90 100 110 120 130 140
Temperaure
0
C
0
0.5
1
1.5
2
2.5
3
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Antonie Equation
Pure Water
5 Mass% KNO
3
10 Mass% KNO
3
Figure 4.9: VLE of Water - Potassium Nitrate.
Form figure 4.6 to 4.9, it was observed that, increase in the salt concentration in the
water showed negligible effect on the reduction in the total vapor pressure of system.
Salting-in effect was due to the hydrophilic nature of sulphate, thiocyanate and nitrate
ion.
4.6 VLE of Ammonia - Water - Salt Systems
The different additives studied includes potassium acetate, copper acetate, ammonium
sulphate, sodium thiocynate, sodium nitrate and potassium nitrate . All these additives
were tested at ammonia concentration of 10, 20 and 30 mass% {mass of ammonia / (mass
of ammonia + mass of water)} and at different concentrations of additives.
4.6.1 Effect of Acetates (CH
3
COOK, (CH
3
COO)
2
Cu)
Following acetates were used to study the effect on the VLE of ammonia-water-salt sys-
tem.
29
Thermodynamic Study of Ternary Refrigerant Equilibria
1. Potassium Acetate
2. Copper Acetate
The effect of potassium acetate and copper acetate on the VLE of ammonia-water system
were studied at different conc. as shown in the figures from 4.10 to 4.15.
Potassium acetate was studied at 5, 10, 15 and 20 mass% of salt concentration as
shown in figure form 4.10 to 4.12. Use of 5, 10, 15 and 20 mass% of potassium acetate
leads to salting-out at 10, 20 and 30 mass% of ammonia. It has been observed that, as the
concentration of salt increases, the total vapor pressure of the system increases for 10, 20
and 30 Mass% of ammonia, but salt effect is small on the total vapor pressure of system.
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
0
C
0
1
2
3
4
5
6
7
8
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al.
0 Mass% CH
3
COOK
5 Mass% CH
3
COOK
10% CH
3
COOK
15% CH
3
COOK
20% CH
3
COOK
Figure 4.10: VLE of Ammonia - Water - Potassium Acetate in 10 Mass % Ammonia
Solution.
30
Thermodynamic Study of Ternary Refrigerant Equilibria
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
0
C
0
2
4
6
8
10
12
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al.
0 Mass% CH
3
COOK
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
Figure 4.11: VLE of Ammonia - Water - Potassium Acetate in 20 Mass % Ammonia
Solution.
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
0
C
0
2
4
6
8
10
12
14
16
18
20
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al.
0 Mass% CH
3
COOK
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 4.12: VLE of Ammonia - Water - Potassium Acetate in 30 Mass % Ammonia
Solution.
Copper acetate was studied at 5, 10, 15 and 20 mass% of salt concentration as shown
in figure 4.13 to 4.15 at 10, 20 and 30 mass% of ammonia. Copper acetate shows a
salting-out effect, as we increase the salt conc. Also it was observed that, this effect
31
Thermodynamic Study of Ternary Refrigerant Equilibria
was increasing as the ammonia concentration was increased. Copper acetate showed
salting-out effect due to hydrophilic nature of acetate group. At high ammonia conc.
copper acetate showed salting-in effect, this may be due to interaction between Cu
++
and ammonia.
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
o
C
0
1
2
3
4
5
6
7
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al.
Exp NH
3
-H
2
O
Exp 5 Mass% (CH
3
COO)
2
Cu
Exp 10 Mass% (CH
3
COO)
2
Cu
Exp 15 Mass% (CH
3
COO)
2
Cu
Figure 4.13: VLE of Ammonia - Water - Copper Acetate in 10 Mass % Ammonia Solu-
tion.
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
o
C
0
1
2
3
4
5
6
7
8
9
10
11
12
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al.
Exp NH
3
-H
2
O
Exp 5 Mass% (CH
3
COO)
2
Cu
Exp 10 Mass% (CH
3
COO)
2
Cu
Exp 15 Mass% (CH
3
COO)
2
Cu
Exp 20 Mass% (CH
3
COO)
2
Cu
Figure 4.14: VLE of Ammonia - Water - Copper Acetate in 20 Mass % Ammonia Solu-
tion.
32
Thermodynamic Study of Ternary Refrigerant Equilibria
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
o
C
0
3
6
9
12
15
18
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al.
Exp NH
3
-H
2
O
Exp 5 Mass% (CH
3
COO)
2
Cu
Exp 10 Mass% (CH
3
COO)
2
Cu
Exp 15 Mass% (CH
3
COO)
2
Cu
Exp 20 Mass% (CH
3
COO)
2
Cu
Figure 4.15: VLE of Ammonia - Water - Copper Acetate in 30 Mass % Ammonia Solu-
tion.
Acetate group is hydrophilic in nature. Because of the interactions of potassium
acetate and copper acetate with water, salting out effect was noticed. Potassium acetate
salt showed more salting-out effect as compared to the effect shown by copper salt. This
is due to more solubility of potassium salt in water than copper salt.
4.6.2 Effect of Ammonium Sulphate ((NH
4
)
2
SO
4
)
The effect of ammonium sulphate on the VLE of ammonia-water system was studied at
different conc. as shown in the figures from 4.16 to 4.18. 5, 10, 15 and 20 mass% conc.
of salt were studied at 10, 20 and 30 mass% of ammonia, the salt shows the salting-
out effect. It was observed that, salting-out effect increases with conc. of ammonium
sulphate.
NH
3
(aq) +H
2
O(aq) ⇋NH
+
4
(aq) +OH

(aq)
33
Thermodynamic Study of Ternary Refrigerant Equilibria
H
2
O (l) ⇋H
+
(aq) +OH

(aq)
(NH
4
)
2
SO
4
(s) →2NH
+
4
(aq) +SO
2−
4
(aq)
SO
−2
4
ion is hydrophilic in nature and shows interaction with water, because of
the complex formation with water, salting-out effect was seen. Due to this, less water
molecule is available for ammonia, therefor free ammonia from ammonia-water mixture,
increases the total vapor pressure of the system. The complex formation of SO
−2
4
with
water molecule is given below.
SO
2−
4
(aq) +H
+
(aq) ⇋HSO

4
(aq)
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
o
C
0
1
2
3
4
5
6
7
8
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al.
Exp NH
3
-H
2
O
Exp 5 Mass% (NH
4
)
2
SO
4
Exp 10 Mass% (NH
4
)
2
SO
4
Exp 15 Mass% (NH
4
)
2
SO
4
Exp 20 Mass% (NH
4
)
2
SO
4
Figure 4.16: VLE of Ammonia - Water - Ammonium Sulphate in 10 Mass % Ammonia
Solution.
34
Thermodynamic Study of Ternary Refrigerant Equilibria
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
o
C
0
2
4
6
8
10
12
14
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al.
Exp NH
3
-H
2
O
Exp 5 Mass% (NH
4
)
2
SO
4
Exp 10 Mass% (NH
4
)
2
SO
4
Exp 15 Mass% (NH
4
)
2
SO
4
Exp 20 Mass% (NH
4
)
2
SO
4
Figure 4.17: VLE of Ammonia-Water-Ammonium Sulphate in 20 Mass % Ammonia
solution.
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
o
C
0
2
4
6
8
10
12
14
16
18
20
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al.
Exp NH
3
-H
2
O
Exp 5 Mass% (NH
4
)
2
SO
4
Exp 10 Mass% (NH
4
)
2
SO
4
Exp 15 Mass% (NH
4
)
2
SO
4
Exp 20 Mass% (NH
4
)
2
SO
4
Figure 4.18: VLE of Ammonia - Water - Ammonium Sulphate in 30 Mass % Ammonia
Solution.
35
Thermodynamic Study of Ternary Refrigerant Equilibria
4.6.3 Sodium Thiocyanate (NaSCN)
The effect of sodium thiocyanate on VLE of ammonia-water system studied at 5, 10, 15
and 20 mass% of salt on on 10, 20 and 30 mass% of ammonia as shown in figure 4.19 to
4.21.
From figure 4.19 to 4.21, we can observe that, as we increase the concentration of
salt in ammonia-water mixture, the system showed salting-out effect. This is due to the
hydrophilic nature of SCN

ion, it showed a strong interaction with water molecule due
to electrostatic force of attraction. We can observe that, after 10 mass% of salt , effect
on total vapor pressure remains constant even after we increase the salt concentration, it
means that saturation of salt occures in the ammonia - water solution at 10 mass% salt.
30 40 50 60 70 80 90 100 110 120
Temperature
0
C
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al
Exp NH
3
-H
2
O
Exp 5 Mass% NaSCN
Exp 10 mass% NaSCN
Exp 15 Mass% NaSCN
Figure 4.19: VLE of Ammonia - Water - Sodium Thiocyanate in 10 Mass % Ammonia
Solution.
36
Thermodynamic Study of Ternary Refrigerant Equilibria
30 40 50 60 70 80 90 100 110 120
Temperature
0
C
0
1
2
3
4
5
6
7
8
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al
Exp NH
3
-H
2
O
Exp 5 Mass% NaSCN
Exp 10 Mass% NaSCN
Figure 4.20: VLE of Ammonia - Water - Sodium Thiocyanate in 20 Mass % Ammonia
Solution.
30 40 50 60 70 80 90 100 110 120
Temperature
0
C
0
2
4
6
8
10
12
14
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)

Gillespie et al.
Exp NH
3
-H
2
O
Exp 5 Mass% NaSCN
Exp 10 Mass% NaSCN
Exp 15 Mass% NaSCN
Exp 20 Mass% NaSCN
Figure 4.21: VLE of Ammonia - Water - Sodium Thiocyanate in 30 Mass % Ammonia
Solution.
37
Thermodynamic Study of Ternary Refrigerant Equilibria
4.6.4 Effect of Nitrates (NaNO
3
, KNO
3
)
1. Sodium Nitrate
2. Potassium Nitrate
The effect of Sodium and Potassium Nitrate on the VLE of ammonia - water system
were studied at different conc. as shown in the figures from figure 4.22 to 4.27. 5 and
10 mass%, 5, 10 and 15 mass% and 5, 10, 15 and 20 mass% conc. of salt were studied
at 10, 20 and 30 mass% of ammonia respectively as shown in figure 4.22 to 4.27. As we
increase the concentration of salt in ammonia-water mixture, the system showed salting-
in effect. but, increase in this salt concentration shows very negligible effect on the total
vapor pressure of the system. Sodium nitrate is more soluble in ammonia than in water,
where this salt get solvated with ammonia and shows the salting-in effect.
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
o
C
0
1
2
3
4
5
6
7
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al.
Exp NH
3
-H
2
O
Exp 5 Mass% NaNO
3
Exp 10 Mass% NaNO
3
Figure 4.22: VLE of Ammonia - Water - Sodium Nitrate in 10 Mass % Ammonia solu-
tion.
38
Thermodynamic Study of Ternary Refrigerant Equilibria
30 40 50 60 70 80 90 100 110 120 130 140
Temperaure
o
C
0
1
2
3
4
5
6
7
8
9
10
11
12
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al.
Exp NH
3
-H
2
O
Exp 5 Mass% NaNO
3
Exp 10 Mass% NaNO
3
Exp 15 Mass% NaNO
3
Figure 4.23: VLE of Ammonia-Water-Sodium Nitrate in 20 Mass % Ammonia Solution.
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
o
C
0
2
4
6
8
10
12
14
16
18
20
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
NH
3
-H
2
O, Gillespie et al.
Exp NH
3
-H
2
O
Exp 5 Mass% NaNO
3
Exp 10 Mass% NaNO
3
Exp 15 Mass% NaNO
3
Exp 20 Mass% NaNO
3
Figure 4.24: VLE of Ammonia-Water-Sodium Nitrate in 30 Mass % Ammonia Solution.
Potassium Nitrate was studied at 5 and 10 mass% of salt concentration on 10, 20 and
30 Mass% of ammonia as shown in figure 4.25 to 4.27. It was observed that, as the salt
concentration increases, it was showing less salting-in effect on system.
39
Thermodynamic Study of Ternary Refrigerant Equilibria
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
o
C
0
1
2
3
4
5
6
7
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al.
Exp NH
3
-H
2
O
Exp 5 Mass% KNO
3
Figure 4.25: VLE of Ammonia - Water - Potassium Nitrate in 10 Mass % Ammonia
Solution.
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
o
C
0
3
6
9
12
15
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
Gillespie et al.
Exp NH
3
-H
2
O
Exp 5 Mass% KNO
3
Figure 4.26: VLE of Ammonia - Water - Potassium Nitrate in 20 Mass % Ammonia
Solution
40
Thermodynamic Study of Ternary Refrigerant Equilibria
30 40 50 60 70 80 90 100 110 120 130 140
Temperature
o
C
0
3
6
9
12
15
18
T
o
t
a
l

V
a
p
o
r

P
r
e
s
s
u
r
e

(
a
t
m
)
NH
3
-H
2
O Gillespie et al.
Exp NH
3
-H
2
O
Exp 5 Mass% KNO
3
Exp 10 Mass% KNO
3
Figure 4.27: VLE of Ammonia - Water - Potassium Nitrate in 30 Mass % Ammonia
Solution
Sodium nitrate and potassium nitrate are more soluble in ammonia than in water,
where these salt get solvated with ammonia and showed the salting-in effect. Also it was
observed that both nitrate showed more or less same effect, this is due to the comparable
size of both sodium and potassium ions.
4.7 Data Fitting
4.7.1 Modeling of Ammonia - Water - Salt Systemby Redlich - Kister
Equation
The variations of total vapor pressure of ammonia-water-salt system with temperature
at different salt concentrations are given in the previous section 4.6. Attempts to fit
this VLE data using NRTL, Wilson and Tan-Wilson activity coefficient models did not
give satisfactory results [Gillespie et al. , 1987]. Gillespie et al. have successfully used
Redlich-Kister activity coefficient model model for ammonia-water binary system and
hence, this model was chosen for data fitting. A modified form of the equations was
41
Thermodynamic Study of Ternary Refrigerant Equilibria
used for this purpose. The equations given by Gillespie et al. [Gillespie et al. , 1987] for
ammonia-water system are as given below:
P = x
1
P
sat
1
γ
1
+x
2
P
sat
2
γ
2
(4.1)
lnγ
1
= x
2
2
¸
A+B(x
2
−x
1
) +C(x
2
−x
1
)
2
¸
+ 2x
2
2
x
1
{B + 2C (x
2
−x
1
)} (4.2)
lnγ
2
= x
2
1
¸
A +B(x
2
−x
1
) +C(x
2
−x
1
)
2
¸
−2x
2
x
2
1
{B + 2C (x
2
−x
1
)} (4.3)
Where,
γ
1
- Activity coefficient of ammonia
γ
2
- Activity coefficient of water
x
1
and x
2
are mole fractions of ammonia and water in the liquid phase
A, B and C are functions of temperature and given as follows;
A = −18.676 + 22.9345(1000/T) −8.8293(1000/T)
2
+ 1.0286(1000/T)
3
(4.4)
B = −0.5 T ≤ 450K (4.5)
B = 3.485 −1.79(1000/T) T > 450K (4.6)
C = −0.445 + 0.098(1000/T)
2
(4.7)
The modified Redlich-Kister activity coefficient model used for Ammonia-Water-Salt
data fitting is as follows;
P = (1 −x
salt
)

x
1
P
sat
1
γ
1
+x
2
P
sat
2
γ
2

(4.8)
42
Thermodynamic Study of Ternary Refrigerant Equilibria
lnγ
1
= x
2
2
¸
A+B(x
2
−x
1
) +C(x
2
−x
1
)
2
¸
+ 2x
2
2
x
1
{B + 2C (x
2
−x
1
)} +a
lnγ
2
= x
2
1
¸
A+B(x
2
−x
1
) +C(x
2
−x
1
)
2
¸
−2x
2
x
2
1
{B + 2C (x
2
−x
1
)} +b
The modified equation contains additional parameters a and b which are functions of
salt concentration and temperature.
x
1
and x
2
are mole fractions of ammonia and water in the liquid phase on salt free
basis and are given as,
x
1
=
moles of ammonia
moles of ammonia +moles of water
(4.9)
x
2
=
moles of water
moles of ammonia +moles of water
(4.10)
Correlation for calculating saturated vapor pressure at a given temperature for ammo-
nia and water are given in equation 3.2 and 3.3.
a - lnγ of ammonia in the presence of salt but in the absence of water.
b - lnγ of water in the presence of salt but in the absence of ammonia.
In the present study, the liquid phase mole fractions of ammonia and water x
1
, x
2
and
total pressure P are measured. Vapor phase compositions y
1
and y
2
are not measured.
The data sets of x
1
, x
2
and P at a particular temperature and salt concentration are used
in equations 4.8, 4.2 and 4.3 and to find the optimised values of a and b using scilab
program. The variation of a and b with salt concentration is expressed in terms of equa-
tions 4.11 and 4.12 respectively. The variations of coefficients for these equations with
temperature is given by from equations 4.14 to 4.17.
a = R
1
x
salt
+R
2
x
salt
(4.11)
b = K
1
x
salt
+K
2
x
2
salt
(4.12)
43
Thermodynamic Study of Ternary Refrigerant Equilibria
where x
salt
is the mole fraction of salt considering total salt dissociation and it is given
by
x
salt
=
moles of salt ×ν
moles of ammonia +moles of water + (moles of salt ×ν)
×100 (4.13)
where ν is the number of ions produced on the dissociation of one molecule of salt
R
1
= D
0
+D
1
×T (4.14)
R
2
= D
2
+D
3
×T (4.15)
K
1
= E
0
+E
1
×T (4.16)
K
2
= E
2
+E
3
×T (4.17)
The values of ’a’ and ’b’ would be zero in the absence of salt and the modified
Redlich-Kister activity coefficient equation reduces to the original Redlich-Kister activ-
ity coefficient equation for the ammonia-water system, given by Gillespie et al [Gillespie
et al. , 1987]. Here ’b’, which is lnγ of water in the presence of salt but in the absence
of ammonia was fitted with total pressure equation 4.8. Same correlation method for
experimental data can used for other salts and constants are evaluated using VLE data of
water-salt as shown in table 4.1.
44
Thermodynamic Study of Ternary Refrigerant Equilibria
Table 4.1: Redlich-Kister constants for Water - Salt
Salt D
0
D
1
D
2
D
3
Potassium Acetate 1.487 -0.017 0.001 0.018
Copper Acetate 2.247 -0.017 0.001 0.231
Ammonium Sulphate 5.0 -0.027 99.571 -0.015
Sodium Thiocyanate -5.0 -0.023 -0.001 -0.001
Sodium Nitrate 5.0 -0.023 -0.001 -0.001
Potassium Nitrate 4.853 -0.021 -0.001 -0.001
Parity plot for water-salts system using the proposed modified Redlich-Kister activity
coefficient equation is shown in Figure 4.28 and 4.29, we can observed that, most of the
points are close to fitted line and showed a ±5% error with experimental points.
0.0 0.5 1.0 1.5 2.0 2.5
0.0
0.5
1.0
1.5
2.0
2.5
Calculated Pressure (atm)
M
e
a
s
u
r
e
d

P
r
e
s
s
u
r
e

(
a
t
m
)
Figure 4.28: Parity plot for Bubble Pressure of Water - Potassium Acetate Mixture.
45
Thermodynamic Study of Ternary Refrigerant Equilibria
0.0 0.5 1.0 1.5 2.0 2.5 3.0
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Calculated Pressure (atm)
M
e
a
s
u
r
e
d

P
r
e
s
s
u
r
e

(
a
t
m
)
Figure 4.29: Parity plot for Bubble Pressure of Water - Copper Acetate Mixture.
0 0.02 0.04 0.06 0.08
x
salt
0.9
0.95
1
1.05
1.1
P
/
(
P
n
o

s
a
l
t

(
1
-
x
s
a
l
t
)
)
Exp 40
0
C
Exp 60
0
C
Exp 80
0
C
40
0
C
60
0
C
80
0
C
Figure 4.30: P/(P
no salt
(1 −x
salt
)) for Water-Potassium Acetate Mixture.
Also, If we plot the graph of P/(P
no salt
(1 − x
salt
)) vs x
salt
, it was observed that,
P/(P
no salt
(1 − x
salt
)) ratio increases with salt concentration. This ratio decreases with
46
Thermodynamic Study of Ternary Refrigerant Equilibria
temperature due to salting-in effect, as shown in above figure. Similar type of graph can
be drown for remaining salts.
on, ’a’ which is lnγ of ammonia in the presence of salt but in the absence of water,
was evaluated fromthe same equation using VLEdata of ammonia-water-salt data and ’b’
constant. The constants for ’a’ are as shown in table 4.2. Parity plot for ammonia-water-
salts system using the proposed modified Redlich-Kister activity coefficient equation is
shown in Figure 4.31 and 4.32.
Table 4.2: Redlich-Kister constants for Ammonia - Water - Salt
Salt E
0
E
1
E
2
E
3
Potassium Acetate 5 -0.033 225.2 -0.251
Copper Acetate 51.75 -0.166 183.6 0.931
Ammonium Sulphate 56.02 -0.161 -613.5 1.862
Sodium Thiocyanate 5.0 -0.026 273.5 -0.639
Sodium Nitrate -5.0 -0.034 -500.0 2.032
Potassium Nitrate -93.99 0.165 3907 -8.496
0 2 4 6 8 10 12 14 16 18 20
0
2
4
6
8
10
12
14
16
18
20
Calculated Pressure (atm)
M
e
a
s
u
r
e
d

P
r
e
s
s
u
r
e

(
a
t
m
)
Figure 4.31: Parity plot for bubble pressure of Ammonia - Water - Potassium Acetate
Mixture.
47
Thermodynamic Study of Ternary Refrigerant Equilibria
0 2 4 6 8 10 12 14 16
0
2
4
6
8
10
12
14
16
Calculated Pressure (atm)
M
e
a
s
u
r
e
d

P
r
e
s
s
u
r
e

(
a
t
m
)
Figure 4.32: Parity plot for Bubble Pressure of Ammonia - Water - Copper Acetate Mix-
ture.
We can see that most of the data points lie close to the fitted line and showed maxi-
mum ±5% error with experimental pressure. This shows that the results obtained by the
modified Redlich-Kister activity coefficient model are satisfactory. Similarly, parity plot
for remaining salt-water and ammonia-water-salt data can be drown.
After evaluating ’a’ and ’b’ constants for total pressure equation using ammonia-
water-salt and water-salt data respectively, the correlated value and experimental values
were compaired using total pressure equation. From figures it is observed that, the cor-
related pressure and experimental pressure are showed ±5%, which is good agreement
with experimental data.
48
Thermodynamic Study of Ternary Refrigerant Equilibria
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
x
1
0
0.5
1
1.5
2
2.5
3
3.5
4
B
u
b
b
l
e

P
r
e
s
s
u
r
e

(
a
t
m
)
Exp NH
3
-H
2
O
Exp 5 Mass% CH
3
COOK
Exp 10 Mass% CH
3
COOK
Exp 15 Mass% CH
3
COOK
Exp 20 Mass% CH
3
COOK
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 4.33: Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at
40
0
C.
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
-2000
-1500
-1000
-500
0
500
G
E

J
/
M
o
l
e
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 4.34: Calculated Excess Gibbs free Energy of Ammonia - Water - Potassium
Acetate at 40
0
C.
49
Thermodynamic Study of Ternary Refrigerant Equilibria
0 0.1 0.2 0.3
x
1
0
1
2
3
4
5
6
B
u
b
b
l
e

P
r
e
s
s
u
r
e

(
a
t
m
)
Exp NH
3
-H
2
O
Exp 5 Mass% CH
3
COOK
Exp 10 Mass% CH
3
COOK
Exp 15 Mass% CH
3
COOK
Exp 20 Mass% CH
3
COOK
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 4.35: Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at
60
0
C.
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
-2000
-1500
-1000
-500
0
500
G
E

J
/
M
o
l
e
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 4.36: Calculated Excess Gibbs Free Energy of Ammonia - Water - Potassium
Acetate at 60
0
C.
The graph of mole fraction of ammonia in vapor phase as shown in appendix showed
that, as we goes on increasing concentration of salt in ammonia-water mixture, the am-
50
Thermodynamic Study of Ternary Refrigerant Equilibria
monia mole fraction in vapor phase was increased. It means that, ammonia showed less
interaction with salt.
0 0.1 0.2 0.3 0.4
x
1
0
1
2
3
4
5
6
7
8
9
10
B
u
b
b
l
e

P
r
e
s
s
u
r
e

(
a
t
m
)
Exp NH
3
-H
2
O
Exp 5 Mass% CH
3
COOK
Exp 10 Mass% CH
3
COOK
Exp 15 Mass% CH
3
COOK
Exp 20 Mass% CH
3
COOK
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 4.37: Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at
80
0
C.
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
-1500
-1250
-1000
-750
-500
-250
0
250
500
G
E

J
/
M
o
l
e
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 4.38: Calculated Excess Gibbs Free Energy of Ammonia - Water - Potassium
Acetate at 80
0
C.
51
Thermodynamic Study of Ternary Refrigerant Equilibria
0 0.1 0.2 0.3 0.4
x
1
0
3
6
9
12
15
B
u
b
b
l
e

P
r
e
s
s
u
r
e

(
a
t
m
)
Exp NH
3
-H
2
O
Exp 5 Mass% CH
3
COOK
Exp 10 Mass% CH
3
COOK
Exp 15 Mass% CH
3
COOK
Exp 20 Mass% CH
3
COOK
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 4.39: Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at
100
0
C.
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
-1000
-800
-600
-400
-200
0
200
G
E

J
/
M
o
l
e
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
Exp 15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 4.40: Calculated Excess Gibbs Free Energy of Ammonia - Water - Potassium
Acetate at 100
0
C.
52
Thermodynamic Study of Ternary Refrigerant Equilibria
0 0.02 0.04 0.06
x
salt
0.9
1
1.1
1.2
1.3
1.4
1.5
P
/
(
P
n
o

s
a
l
t
*
(
1
-
x
s
a
l
t
)
)
Exp 10% NH
3
Exp 20% NH
3
Exp 30% NH
3
10% NH
3
20% NH
3
30% NH
3
Figure 4.41: P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Potassium Acetate mixture at
40
0
C.
0 0.02 0.04 0.06
x
salt
0.8
1
1.2
1.4
1.6
1.8
P
/
(
P
n
o

s
a
l
t
*
(
1
-
x
s
a
l
t
)
)
Exp 10% NH
3
Exp 20% NH
3
Exp 30% NH
3
10% NH
3
20% NH
3
30% NH
3
Figure 4.42: P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Potassium Acetate Mixture at
60
0
C.
53
Thermodynamic Study of Ternary Refrigerant Equilibria
0 0.02 0.04 0.06
x
salt
1
1.1
1.2
1.3
P
/
(
P
n
o

s
a
l
t
(
1
-
x
s
a
l
t
)
)
Exp 10% NH
3
Exp 20% NH
3
Exp 30% NH
3
10% NH
3
20% NH
3
30% NH
3
Figure 4.43: P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Potassium Acetate Mixture at
80
0
C.
If we plot the graph of P/(P
no salt
(1 − x
salt
)) vs x
salt
, it was observed that, as we
increases salt concentration, the P/(P
no salt
(1 −x
salt
)) ratio also increases, due to salting-
out effect, as shown in figure from 4.41 to 4.43. Similar type of graph can be drown at
different temperature and for remaining salts too.
4.7.2 Modeling of Ammonia - Water - Salt System by NRTL Equa-
tion
The Non-Random Two Liquid model (short NRTL equation) is an activity coefficient
model that correlates the activity coefficients of i of a compound with its mole fractions
x
i
in the concerning liquid phase. It is frequently applied in the field of chemical engi-
neering to calculate phase equilibrium. The NRTL equation for the molar excess Gibbs
energy of a binary mixture as a function of mole fraction x
1
and x
2
. The Three-parameter
(α, τ
12
, τ
21
) NRTL equation is
G
E
RT
= x
1
x
2
¸
τ
21
G
21
x
1
+x
2
G
21
+
τ
12
G
12
x
2+
x
1
G
12

(4.18)
where,
54
Thermodynamic Study of Ternary Refrigerant Equilibria
G
12
= exp {−α
12
τ
12
}
G
21
= exp {−α
12
τ
21
}
here α
12
is the non-randomness parameter, which, to a good approximation, does not
depend on the temperature and can often be estimated with sufficient accuracy from the
nature of compound 1 and 2 [Renon and M, 1969]. τ
12
and τ
21
are the dimensionless
interaction parameter, which are related to the interaction energy parameter by;
τ
12
=
g
12
− g
22
RT
τ
21
=
g
12
− g
11
RT
from equation 4.18, the activity coefficient, γ
1
and γ
2
are obtained by differentiation.
The activity coefficients of ammonia is
lnγ
1
= x
2
2
¸
τ
21

G
21
x
1
+ x
2
G
21

2
+
τ
12
G
12
(x
2
+ x
1
G
21
)
2
¸
and activity coefficients of water is given by;
lnγ
2
= x
2
1
¸
τ
12

G
12
x
1
+ x
2
G
12

2
+
τ
21
G
21
(x
2
+ x
1
G
21
)
2
¸
and
τ
12
= D
0
+D
1
×x + D
2
×x
2
+D
3
×x
3
τ
21
= E
0
+ E
1
×x + E
2
×x
2
+E
3
×x
3
55
Thermodynamic Study of Ternary Refrigerant Equilibria
4.7.2.1 Modeling of Ammonia - Water - Salt System by Psudobinary Method
In this study, a different pseudo binary approach was adopted, solvent 1, which salting
out, was designated as component 1

while the mixture of solvent 2 and the salt in a
constant mole ratio was designated component 2

. Defining the system in this manner
means that it can be treated as a binary and the equilibrium relationships governing the
behavior of the system can then be written as [Boone et al. , 1976],
γ
i
x
i
f
0
i
∗ = φ
i
y
i
P
where,
x

1
=
n
1
n
1
+n
2
+n
3
and
x

2
=
n
1
+n
2
n
1
+n
2
+n
3
since the salt is nonvolatile,
y

i
= y
i
since salt have negligible solubility in the salting out component [Rousseau et al. ,
1972] ,
f
0
1
∗ = P
sat
1
one of the effect of salt is to lower the vapor pressure pressure of the liquid in which
it is soluble. For water the vapor pressure lowering is almost a linear function of salt
concentration. Since the salts are more soluble in the water, however reference fugacity
for the latter component may be redefined as,
f
0
2
∗ = P
sat
2
∗ = P
sat
2
−∆P
56
Thermodynamic Study of Ternary Refrigerant Equilibria
Here, The NRTL constants are evaluated using scilab program, where α
12
for ammonia-
water system is 0.4 which is constant for ammonia-water-salt too.
0 0.1 0.2 0.3 0.4
x
1
*
0
0.5
1
1.5
2
2.5
3
3.5
B
u
b
b
l
e

P
r
e
s
s
u
r
e

(
a
t
m
)
Exp NH
3
-H
2
O
Exp 5 Mass% CH
3
COOK
Exp 10 Mass% CH
3
COOK
Exp 15 Mass% CH
3
COOK
Exp 20 Mass% CH
3
COOK
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 4.44: Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at
40
0
C.
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
*
-2000
-1750
-1500
-1250
-1000
-750
-500
-250
0
G
E

J
/
M
o
l
e
NH
3
-H
2
O
NH
3
-H
2
O-CH
3
COOK, M=0.5
NH
NH
3
-H
2
O-CH
3
COOK, M=1
NH
3
-H
2
O-CH
3
COOK, M=1.5
NH
3
-H
2
O-CH
3
COOK, M=2
Figure 4.45: Calculated Excess Gibbs Free Energy of Ammonia - Water - Potassium
Acetate at 40
0
C.
57
Thermodynamic Study of Ternary Refrigerant Equilibria
0 0.1 0.2 0.3 0.4
x
1
*
0
1
2
3
4
5
6
7
B
u
b
b
l
e

P
r
e
s
s
u
r
e

(
a
t
m
)
Exp NH
3
-H
2
O
Exp 5 Mass% CH
3
COOK
Exp 10 Mass% CH
3
COOK
Exp 15 Mass% CH
3
COOK
Exp 20 Mass% CH
3
COOK
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 4.46: Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at
60
0
C.
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
*
-2000
-1750
-1500
-1250
-1000
-750
-500
-250
0
G
E

J
/
M
o
l
e
NH
3
-H
2
O
NH
3
-H
2
O-CH
3
COOK, M=0.5
NH
3
-H
2
O-CH
3
COOK, M=1
NH
3
-H
2
O-CH
3
COOK, M=1.5
NH
3
-H
2
O-CH
3
COOK, M=2
Figure 4.47: Calculated Excess Gibbs Free Energy of Ammonia - Water - Potassium
Acetate at 60
0
C.
58
Thermodynamic Study of Ternary Refrigerant Equilibria
0 0.1 0.2 0.3 0.4
x
1
*
0
3
6
9
12
B
u
b
b
l
e

P
r
e
s
s
u
r
e

(
a
t
m
)
Exp NH
3
-H
2
O
Exp 5 Mass% CH
3
COOK
Exp 10 Mass% CH
3
COOK
Exp 15 Mass% CH
3
COOK
Exp 20 Mass% CH
3
COOK
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 4.48: Calculated Bubble Pressure of Ammonia - Water-Potassium Acetate at
80
0
C.
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
*
-1500
-1250
-1000
-750
-500
-250
0
G
E

J
/
M
o
l
e
NH
3
-H
2
O
NH
3
H
3
-H
2
O-CH
3
COOK, M=0.5
NH
3
-H
2
O-CH
3
COOK, M=1
NH
3
-H
2
O-CH
3
COOK, M=1.5
NH
3
-H
2
O-CH
3
COOK, M=2
Figure 4.49: Calculated Excess Gibbs Free Energy of Ammonia - Water - Potassium
Acetate at 80
0
C.
59
Thermodynamic Study of Ternary Refrigerant Equilibria
0 0.1 0.2 0.3 0.4
x
1
*
0
5
10
15
20
B
u
b
b
l
e

P
r
e
s
s
u
r
e

(
a
t
m
)
Exp NH
3
-H
2
O
Exp 5 Mass% CH
3
COOK
Exp 10 Mass% CH
3
COOK
Exp 15 Mass% CH
3
COOK
Exp 20 Mass% CH
3
COOK
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 4.50: Calculated Bubble Pressure of Ammonia - Water - Potassium Acetate at
100
0
C.
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
*
-1500
-1250
-1000
-750
-500
-250
0
G
E

J
/
M
o
l
e
NH
3
-H
2
O
NH
3
-H
2
O-CH
3
COOK, M=0.5
NH
3
-H
2
O-CH
3
COOK, M=1
NH
3
-H
2
O-CH
3
COOK, M=1.5
NH
3
-H
2
O-CH
3
COOK, M=2
Figure 4.51: Calculated Excess Gibbs Free Energy of Ammonia - Water - Potassium
Acetate at 100
0
C.
From the figures we observed that, experimental pressure and correlated pressure
were showed ± 5%. error. Also mole fraction of ammonia in vapor phase is increasing
as salt concentration increases. Same correlation method for experimental data can used
for other salts. Constants for other salt is given in tables form 4.3 to 4.14.
60
Thermodynamic Study of Ternary Refrigerant Equilibria
Table 4.3: Table showing values of D
0
, D
1
, D
2
, and D
3
at different Temperature for
Ammonia - Water - Potassium Acetate Mixture.
Temperature
0
C D
0
D
1
D
2
D
3
40 0.109 -3.124 3.032 -0.829
50 -1.998 3.264 -2.039 0.414
60 -1.031 0.237 -0.091 0.027
70 -0.602 0.600 -0.763 0.228
80 0.457 -2.466 1.835 -0.447
90 -0.835 0.651 -0.213 -0.019
100 -0.731 1.020 -0.627 0.129
110 0.254 -1.443 1.516 -0.404
120 -0.452 1.749 -1.759 0.593
130 -1.218 2.496 -1.210 0.267
Table 4.4: Table showing values of E
0
, E
1
, E
2
, and E
3
at different Temperature for Am-
monia - Water - Potassium Acetate Mixture.
Temperature
0
C E
0
E
1
E
2
E
3
40 -1.660 1.878 -1.860 0.533
50 0.026 -2.632 1.718 -0.344
60 -0.636 -0.130 0.135 -0.034
70 -0.915 -0.520 0.796 -0.232
80 -1.963 2.871 -2.103 0.519
90 -0.594 -0.245 -0.051 0.086
100 -0.602 -0.788 0.501 -0.091
110 -0.581 -1.062 0.728 -0.165
120 -0.794 -0.977 1.008 -0.337
130 0.060 -2.338 1.322 -0.277
Table 4.5: Table showing values of D
0
, D
1
, D
2
, and D
3
at different Temperature for
Ammonia - Water - Copper Acetate Mixture.
Temperature
0
C D
0
D
1
D
2
D
3
40 6.804 -37.21 48.87 -18.87
50 -0.030 3.317 -10.39 6.512
60 -0.192 -1.345 0.961 -0.621
70 -0.168 -1.688 0.547 0.328
80 -1.692 7.276 -14.84 8.029
90 0.001 -0.042 -2.903 1.920
100 -1.455 5.596 -11.72 6.393
110 0.202 -0.941 -1.393 1.033
120 0.064 -1.363 0.725 0.087
130 1.074 -8.324 16.39 -8.641
61
Thermodynamic Study of Ternary Refrigerant Equilibria
Table 4.6: Table showing values of E
0
, E
1
, E
2
, and E
3
at different Temperature for Am-
monia - Water - Copper Acetate Mixture.
Temperature
0
C E
0
E
1
E
2
E
3
40 -10.10 49.13 -70.57 30.53
50 -1.350 -3.556 10.520 -6.448
60 -1.409 1.636 -1.090 0.629
70 -1.255 1.254 0.831 -1.115
80 0.683 -9.359 19.36 -10.44
90 -1.150 -0.944 4.584 -2.609
100 0.479 -7.290 15.44 -0.840
110 -1.041 -0.573 3.938 -2.218
120 -1.103 1.103 -0.434 -0.227
130 -1.695 4.549 -9.062 4.788
Table 4.7: Table showing values of D
0
, D
1
and D
2
at different Temperature for Am-
monia - Water - Ammonium Sulphate Mixture.
Temperature
0
C D
0
D
1
D
2
40 -0.834 -0.542 0.743
50 -1.998 2.991 -1.132
60 -1.508 1.188 -0.392
70 -1.307 1.450 -0.569
80 -0.987 0.150 0.019
90 -0.824 0.739 -0.106
100 -0.824 0.739 -0.106
110 -2.940 6.849 -2.785
120 1.203 0.016 -0.032
130 1.227 0.144 -0.107
Table 4.8: Table showing values of E
0
, E
1
and E
2
at different Temperature for Ammo-
nia - Water - Ammonium Sulphate Mixture.
Temperature
0
C E
0
E
1
E
2
40 -0.640 0.101 -0.398
50 0.054 -1.977 0.746
60 0.212 -1.215 0.470
70 -0.129 -1.168 0.503
80 -0.137 -0.076 -0.007
90 -0.379 -0.654 0.177
100 -0.174 0.019 -0.406
110 0.679 -3.889 1.639
120 -1.799 -0.038 0.082
130 -1.843 -0.393 0.288
62
Thermodynamic Study of Ternary Refrigerant Equilibria
Table 4.9: Table showing values of D
0
, D
1
and D
2
at different Temperature for Ammo-
nia - Water - Sodium Thiocyanate Mixture.
Temperature
0
C D
0
D
1
D
2
40 0.641 1.889 -1.282
50 -1.838 4.481 -1.777
60 1.097 0.863 -0.577
70 -0.995 3.514 -1.154
80 -1.635 4.799 -1.948
90 1.271 -0.055 0.019
100 -0.875 0.552 -0.207
110 -0.165 1.152 -0.478
Table 4.10: Table showing values of E
0
, E
1
and E
2
at different Temperature for Am-
monia - Water - Sodium Thiocyanate Mixture.
Temperature
0
C E
0
E
1
E
2
40 -2.181 -0.429 0.362
50 -0.934 -1.845 0.743
60 -2.136 -0.192 0.181
70 -1.286 -1.184 0.393
80 -0.843 -1.922 0.787
90 -1.883 0.146 -0.049
100 -0.769 -0.311 0.128
110 -1.178 -0.505 0.024
Table 4.11: Table showing values of D
0
, D
1
and D
2
at different Temperature for Am-
monia - Water - Sodium Nitrate Mixture.
Temperature
0
C D
0
D
1
D
2
40 -0.657 -0.370 0.015
50 -1.027 0.190 -0.049
60 -0.762 0.072 -0.013
70 -8.205 4.759 -0.678
80 4.931 -3.957 0.651
90 -0.239 -0.081 0.010
100 -0.239 -0.095 0.010
110 -0.161 1.236 -0.255
120 1.261 0.016 -0.002
130 1.270 0.013 -0.002
63
Thermodynamic Study of Ternary Refrigerant Equilibria
Table 4.12: Table showing values of E
0
, E
1
and E
2
at different Temperature for Am-
monia - Water - Sodium Nitrate Mixture.
Temperature
0
C E
0
E
1
E
2
40 -1.222 0.049 0.039
50 -1.020 -0.248 0.058
60 -1.109 -0.083 0.011
70 -1.089 -0.248 0.030
80 0.191 -1.128 0.195
90 -1.307 0.079 -0.012
100 -0.763 0.104 -0.005
110 -2.066 0.037 0.011
120 -1.194 -0.053 0.008
130 -1.918 -0.058 0.008
Table 4.13: Table showing values of D
0
and D
1
at different Temperature for Ammonia
- Water - Potassium Nitrate Mixture.
Temperature
0
C D
0
D
1
40 -0.813 -0.257
50 -0.819 -0.211
60 -2.057 0.591
70 -0.490 -0.123
80 -0.639 -0.144
90 -1.113 0.296
100 -0.193 -0.258
110 -0.256 -0.182
120 -0791 1.029
130 -0.020 0.649
Table 4.14: Table showing values of E
0
and E
1
at different Temperature for Ammonia -
Water - Potassium Nitrate Mixture.
Temperature
0
C E
0
E
1
40 -1.243 0.224
50 -1.161 0.235
60 0.590 -0.783
70 -1.238 0.083
80 -0.962 0.126
90 -0.263 -0.388
100 -1.197 0.224
110 -0.993 0.132
120 -0.863 -0.540
130 -1.247 -0.401
64
Chapter 5
Conclusions
65
Thermodynamic Study of Ternary Refrigerant Equilibria
The addition of salt to binary Ammonia-water system changes the VLE of system of
the solvents because of the interactions between the salt ions and solvent components.
VLE studies were necessary for ammonia-water-salt ternary system to suggest necessary
changes in AAR working fluid. The different additives studied includes Potassium Ac-
etate, Copper acetate, Ammonium Sulphate, Sodium Thiocyanate, Sodium Nitrate and
Potassium Nitrate using rocked static VLE cell at different concentrations of salt and
various temperature on 10, 20 and 30 mass% ammonia concentration.
Amongest the tested additives, potassium acetate showed maximum salting-out ef-
fect. The salting-out effect showed by the potassium acetate was mainly because of more
solubility and non reactive nature of salt as compaired to remaining salting-out salts.
Sodium nitrate showed a maximum salting-in effect as compared to potassium nitrate.
This is due to more salt get solvated with ammonia and showed the salting-in effect as
compaired to potassium nitrate. PTx data was generated for ammonia-water-salt ternary
system up to liquid phase ammonia concentration of 30 mass%. Redlich-Kister activity
coefficient model was modified to correlate the experimental VLE data for ammonia -
water - salt system. The modified Redlich-Kister model showed maximum ±5% error
with measured data. Also experimental VLE data was correlated using NRTL equation
by pseudo binary concept, showed maximum ±5% error with measured data.
66
Chapter 6
Future Scope
67
Thermodynamic Study of Ternary Refrigerant Equilibria
Ionic liquids have been used by many researcheres for changing the VLE of binary
systems. These ionic liquids may have potential to alter the VLE of ammonia-water
system and hence, the studies using ionic liquids as an additives needs to be carried out.
There are lesser number of studies on ammonia-water system. VLE data for ammonia-
water-salt system is scarce and studies on the system should be carried out using different
additives at different temperature and throughout the liquid phase ammonia concentra-
tion.
68
Nomenclature
69
Thermodynamic Study of Ternary Refrigerant Equilibria
Abbreviations
AAR Ammonia Absorption Refrigeration
f fugacity
G Gibb’s free energy
R Universal gas Constant
T Temperature, K
x Liquid phase mole fraction
y Vapor phase mole fraction
Z Compressibility factor
Subscripts
1 Ammonia
2 Water
c Critical
P Constant pressure
T Constant temperature
Superscripts
E Excess
sat Saturated
Greek Letters
γ Activity Coefficient
φ Fugacity Coefficient
70
Appendix
71
Thermodynamic Study of Ternary Refrigerant Equilibria
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
y
1
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 6.1: Calculated mole fraction of Ammonia in vapor phase for Ammonia - Water -
Potassium Acetate at 40
0
C using Redlich - Kister equation.
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
y
1
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 6.2: Calculated mole fraction of Ammonia in vapor phase for Ammonia - Water -
Potassium Acetate at 60
0
C using Redlich - Kister Equation.
72
Thermodynamic Study of Ternary Refrigerant Equilibria
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
y
1
Figure 6.3: Calculated mole fraction of Ammonia in vapor phase for Ammonia - Water -
Potassium Acetate at 80
0
C using Redlich - Kister Equation.
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
y
1
NH
3
-H
2
O
5 Mass% CH
3
COOK
10 Mass% CH
3
COOK
15 Mass% CH
3
COOK
20 Mass% CH
3
COOK
Figure 6.4: Calculated mole fraction of Ammonia in vapor phase for Ammonia - Water -
Potassium Acetate at 100
0
C using Redlich - Kister Equation.
73
Thermodynamic Study of Ternary Refrigerant Equilibria
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
*
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
y
1
*
NH
3
-H
2
O
NH
3
-H
2
O-CH
3
COOK, M=0.5
NH
3
-H
2
O-CH
3
COOK, M=1
NH
3
-H
2
O-CH
3
COOK, M=1.5
NH
3
-H
2
O-CH
3
COOK, M=2
Figure 6.5: Calculated mole fraction of Ammonia in vapor phase for Ammonia - Water -
Potassium Acetate at 40
0
C using NRTL Equation.
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
*
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
y
1
*
NH
3
-H
2
O
NH
3
-H
2
O-CH
3
COOK, M=0.5
NH
3
-H
2
O-CH
3
COOK, M=1
NH
3
-H
2
O-CH
3
COOK, M=1.5
NH
3
-H
2
O-CH
3
COOK, M=2
Figure 6.6: Calculated mole fraction of Ammonia in vapor phase for Ammonia - Water -
Potassium Acetate at 60
0
C using NRTL Equation.
74
Thermodynamic Study of Ternary Refrigerant Equilibria
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
*
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
y
1
*
NH
3
-H
2
O
NH
3
-H
2
O-CH
3
COOK, M=1.5
NH
3
-H
2
O-CH
3
COOK, M=1
NH
3
-H
2
O-CH
3
COOK, M=1.5
NH
3
-H
2
O-CH
3
COOK, M=2
Figure 6.7: Calculated mole fraction of Ammonia in vapor phase for Ammonia - Water -
Potassium Acetate at 80
0
C using NRTL Equation.
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x
1
*
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
y
1
*
NH
3
-H
2
O
NH
3
-H
2
O-CH
3
COOK, M=0.5
NH
3
-H
2
O-CH
3
COOK, M=1
NH
3
-H
2
O-CH
3
COOK, M=1.5
NH
3
-H
2
O-CH
3
COOK, M=2
Figure 6.8: Calculated mole fraction of Ammonia in vapor phase for Ammonia - Water -
Potassium Acetate at 100
0
C using NRTL Equation.
75
Thermodynamic Study of Ternary Refrigerant Equilibria
Table 6.1: P/(P
no salt
(1 −x
salt
)) for Water - Potassium Acetate Mixture.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass %
40 0.98 0.972 0.94
50 0.99 0.81 0.95
60 0.9 0.81 0.91
70 0.97 0.90 0.96
80 1.05 1.00 1.05
90 0.95 0.95 0.97
100 1.02 1.04 1.06
110 0.98 0.99 1.02
120 1 0.92 1.05
130 0.98 0.99 1.02
Table 6.2: P/(P
no salt
(1 −x
salt
)) for Water- Copper Acetate Mixture.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass %
40 0.96 0.97 0.9
50 0.95 0.96 0.87
60 0.9 0.91 0.85
70 0.98 0.99 0.91
80 1.1 1.11 1.02
90 1.01 1.02 0.94
100 0.9 0.91 0.86
110 1.05 1.07 0.95
120 1.09 1.11 1
130 1.06 1.07 1
Table 6.3: P /( P
no salt
(1 −x
salt
) ) for Water - Ammonium Sulphate Mixture.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass %
40 1.01 1 1.04
50 0.97 0.93 0.93
60 0.85 0.86 0.89
70 0.93 0.94 0.95
80 0.9 0.86 0.89
90 0.76 0.8 0.81
100 0.67 0.68 0.7
110 0.98 1 1.02
120 1 1.03 1.05
130 0.92 0.94 0.96
76
Thermodynamic Study of Ternary Refrigerant Equilibria
Table 6.4: P/(P
no salt
(1 −x
salt
)) for Water - Sodium Thiocyanate Mixture.
Temperature
0
C 5 Mass % 10 Mass %
40 0.98 0.98
50 0.92 0.82
60 0.89 0.83
70 1 0.92
80 0.98 1.01
90 0.94 0.97
100 1.02 1.05
110 1.03 1.06
Table 6.5: P/(P
no salt
(1 −x
salt
)) for Water - Sodium Nitrate Mixture.
Temperature
0
C 5 Mass % 10 Mass %
40 0.97 1.01
50 0.93 0.94
60 0.89 0.9
70 0.97 0.96
80 1.00 1.01
90 1.02 1.04
100 1.02 1.05
110 0.98 1
120 1.05 1.07
130 1.02 1.04
Table 6.6: P/(P
no salt
(1 −x
salt
)) for Water - Potassium Nitrate mixture.
Temp
0
C 5 Mass % 10 Mass %
40 0.98 1
50 0.92 0.93
60 0.89 0.85
70 0.97 0.93
80 0.98 1
90 1.02 1.02
100 1.02 1.04
110 1.02 1.01
120 1.04 1.07
130 1.02 1.04
77
Thermodynamic Study of Ternary Refrigerant Equilibria
Table 6.7: P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Potassium Acetate Mixture in 30
Mass % Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass % 20 Mass %
40 1.02 1.09 1.24 1.28
50 1.08 1.17 1.32 1.36
60 1.09 1.2 1.31 1.38
70 1.09 1.2 1.3 1.37
80 1.07 1.17 1.26 1.33
90 1.08 1.12 1.2 1.28
100 1.04 1.09 1.18 1.26
110 1.03 1.08 1.12 1.2
120 1.03 1.08 1.11 1.14
130 1.02 1.05 1.07 1.11
Table 6.8: P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Potassium Acetate mixture in 20
Mass % Ammonia solution.
Temp
0
C 5 Mass % 10 Mass % 15 Mass % 20 Mass %
40 1.02 1.15 1.17 1.47
50 1.2 1.33 1.42 1.59
60 1.02 1.16 1.32 1.61
70 1.05 1.13 1.25 1.46
80 1.08 1.15 1.24 1.4
90 1.05 1.12 1.18 1.3
100 1.04 1.09 1.19 1.29
110 1.03 1.09 1.14 1.22
120 1.03 1.08 1.11 1.18
130 1.03 1.06 1.11 1.14
Table 6.9: P/(P
no salt
(1 −x
salt
)) for Ammonia - Water - Potassium Acetate Mixture in 10
Mass % Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass% 20 Mass %
40 1.06 1.15 1.3 1.66
50 1.14 1.59 1.64 1.91
60 1.15 1.17 1.21 1.44
70 1.14 1.23 1.25 1.36
80 1.2 1.25 1.26 1.29
90 1.11 1.2 1.22 1.24
100 1.09 1.19 1.21 1.29
110 1.12 1.17 1.24 1.29
120 1.15 1.18 1.28 1.36
130 1.05 1.17 1.24 1.38
78
Thermodynamic Study of Ternary Refrigerant Equilibria
Table 6.10: P/(P
no salt
(1 − x
salt
)) for Ammonia - Water - Copper Acetate Mixture in 30
Mass % Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass % 20 Mass %
40 1.04 1.23 1.44 1.46
50 1.21 1.35 1.46 1.58
60 1.14 1.22 1.27 1.32
70 1.12 1.22 1.27 1.34
80 1.09 1.21 1.26 1.31
90 1.05 1.15 1.23 1.32
100 1.1 1.17 1.21 1.17
110 1.03 1.11 1.15 1.1
120 1.03 1.03 1.04 1.04
130 0.93 0.94 0.94 0.94
Table 6.11: P/(P
no salt
(1 − x
salt
)) for Ammonia - Water - Copper Acetate Mixture in 20
Mass % Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass % 20 Mass %
40 0.93 0.94 1.37 1.39
50 1.11 1.33 1.41 1.57
60 1.01 1.1 1.25 1.34
70 1.01 1.05 1.12 1.24
80 1.03 1.06 1.12 1.17
90 1.04 1.08 1.12 1.16
100 1.01 1.03 1.06 1.1
110 1.07 1.04 1.02 1
120 1.06 1.05 1.05 1.03
130 0.93 0.94 0.92 0.93
Table 6.12: P/(P
no salt
(1 − x
salt
)) for Ammonia - Water - Copper Acetate Mixture in 10
Mass % Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass %
40 2.14 1 1
50 1.88 1.7 1.53
60 1.45 1.33 1.34
70 1.19 1.14 1.15
80 1.17 1.18 1.1
90 1.11 1.03 1
100 1.06 1.06 1.06
110 1.07 1.04 1.03
120 1.08 1.03 1.04
130 0.98 1 1.01
79
Thermodynamic Study of Ternary Refrigerant Equilibria
Table 6.13: P/ (P
no salt
(1−x
salt
)) for Ammonia - Water - AmmoniumSulphate Mixture
in 30 Mass % Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass % 20 Mass %
40 1.26 1.29 1.31 1.34
50 1.3 1.32 1.35 1.41
60 1.31 1.34 1.43 1.53
70 1.2 1.28 1.33 1.39
80 1.26 1.31 1.4 1.44
90 1.2 1.25 1.31 1.37
100 1.18 1.22 1.27 1.32
110 1.02 1.06 1.09 1.11
120 0.84 0.88 0.9 0.92
130 0.72 0.76 0.78 0.8
Table 6.14: P/ (P
no salt
(1−x
salt
) ) for Ammonia - Water - AmmoniumSulphate Mixture
in 20 Mass % Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass % 20 Mass %
40 1.17 1.29 1.52 2.15
50 1.32 1.75 1.89 2.11
60 1.28 1.48 1.62 1.9
70 1.17 1.35 1.39 1.68
80 1.3 1.4 1.45 1.6
90 1.19 1.32 1.44 1.62
100 1.14 1.3 1.45 1.5
110 1.06 1.22 1.43 1.47
120 1.01 1.07 1.19 1.31
130 1.02 1.07 1.14 1.23
Table 6.15: P/( P
no salt
(1−x
salt
)) for Ammonia - Water - AmmoniumSulphate Mixture
in 10 Mass % Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass % 20 Mass %
40 1.43 1.48 1.85 1.88
50 1.26 1.28 1.31 1.33
60 1.16 1.3 1.35 1.45
70 1.12 1.23 1.26 1.28
80 1.1 1.19 1.28 1.45
90 1.04 1.11 1.2 1.33
100 1.03 1.08 1.27 1.38
110 1.06 1.13 1.28 1.37
120 1.09 1.17 1.27 1.34
130 1 1.11 1.13 1.33
80
Thermodynamic Study of Ternary Refrigerant Equilibria
Table 6.16: P/ (P
no salt
(1−x
salt
)) for Ammonia - Water - Sodium Thiocyanate Mixture
in 30 Mass % of Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass % 20 Mass %
40 1.01 1.18 1.29 1.31
50 1.06 1.16 1.21 1.27
60 1.03 1.13 1.17 1.24
70 1.04 1.1 1.12 1.17
80 1.03 1.06 1.1 1.16
90 1.04 1.08 1.11 1.16
100 1.06 1.11 1.13 1.15
110 1.05 1.1 1.11 1.14
Table 6.17: P/ (P
no salt
(1−x
salt
)) for Ammonia - Water - Sodium Thiocyanate Mixture
in 20 Mass % Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass %
40 1.19 1.22
50 1.44 1.54
60 1.36 1.39
70 1.27 1.29
80 1.21 1.23
90 1.21 1.23
100 1.19 1.21
110 1.13 1.16
Table 6.18: P/ ( P
no salt
(1 −x
salt
) ) for Ammonia - Water - Sodium Thiocyanate Mix-
ture in 10 Mass % Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass %
40 2.04 1.85 1.89
50 1.59 1.62 1.65
60 1.46 1.34 1.36
70 1.24 1.26 1.29
80 1.34 1.28 1.29
90 1.3 1.29 1.32
100 1.26 1.24 1.25
110 1.17 1.17 1.19
81
Thermodynamic Study of Ternary Refrigerant Equilibria
Table 6.19: P/(P
no salt
(1 − x
salt
)) for Ammonia - water - Sodium Nitrate Mixture in 30
Mass % Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass % 20 Mass %
40 1.01 1.03 1.05 1.13
50 1.01 1.03 1.05 1.06
60 0.98 1 1.03 1.04
70 1 1 1 1.02
80 0.97 0.99 1.03 1.06
90 1.01 1.05 1.1 1.12
100 0.97 1 1.05 1.1
110 0.91 0.94 1 1.04
120 0.81 0.85 0.88 0.89
130 0.72 0.74 0.78 0.79
Table 6.20: P/(P
no salt
(1 − x
salt
)) for Ammonia - Water - Sodium Nitrate Mixture in 20
Mass % Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass % 15 Mass %
40 0.66 0.55 0.55
50 0.94 0.93 0.87
60 0.97 0.9 0.9
70 0.99 0.91 0.88
80 1 1 0.97
90 1.01 0.99 0.98
100 1.02 1 1
110 1 0.95 0.97
120 0.96 0.96 0.98
130 0.97 0.96 0.98
Table 6.21: P/(P
no salt
(1 − x
salt
)) for Ammonia - Water - Sodium Nitrate Mixture in 10
Mass % Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass %
40 0.75 0.77
50 0.85 0.77
60 1.02 1.04
70 1.02 0.95
80 1.03 0.98
90 0.93 0.95
100 0.95 0.94
110 1.04 0.99
120 1 1.02
130 1 1.01
82
Thermodynamic Study of Ternary Refrigerant Equilibria
Table 6.22: P/(P
no salt
(1 − x
salt
)) for Ammonia - Water - Potassium Nitrate Mixture in
30 Mass % Ammonia Solution.
Temperature
0
C 5 Mass % 10 Mass %
40 1.01 1.02
50 1.02 1.04
60 1.01 1.03
70 1.02 1.03
80 1.01 1.02
90 1.01 1.03
100 1.02 1.04
110 1.01 1
120 0.87 0.84
130 0.79 0.72
Table 6.23: P/(P
no salt
(1 − x
salt
)) for Ammonia - Water - Potassium Nitrate Mixture in
20 Mass % Ammonia Solution.
Temperature
0
C 5 Mass %
40 0.81
50 0.97
60 0.83
70 0.87
80 0.9
90 0.92
100 0.89
110 0.89
120 0.89
130 0.76
Table 6.24: P/(P
no salt
(1 − x
salt
)) for Ammonia - Water - Potassium Nitrate Mixture in
10 Mass % Ammonia Solution.
Temperature
0
C 5 Mass %
40 0.67
50 0.84
60 1
70 0.95
80 0.99
90 0.97
100 0.94
110 0.98
120 1
130 1.02
83
References
Abovsky, V. 1996. Thermodynamics of ammonia-water mixture. Fluid Phase Equilibria,
116, 170–176.
Boone, J. E., Rousseau, W., and Schoenborn, E. M. 1976. The Correlation of vapor-liquid
euilibrium data for salt-containing system. Adv. Chem. Ser., 155, 36–52.
Brass, M., Pritzel, T., Schulte, E., and keller, J.U. 2000. Measurements of Vapor-Liquid
Equilibria in the Systems ammonia-water-NaOHand Ammonia-water-KOHat Tem-
peratures of 303 and 318 K and Pressures 0.1 MPa < P < 1.3 MPa. International
Journal of Thermophysics, 21(4), 883–898.
Darwish, N.A., and Al-Anbar, Z.A. 1997. Isobaric vapor-liquid equilibria of chloroform
- ethanol and chloroform - ethanol - calcium chloride at 94.0 KPa. Fluid Phase
Equilibria, 131, 259.
Gillespie, P. C., Wilding, W. C., and Wilson, G. M. 1987. Vapor-liquid equilibrium
measurements on the ammonia-water system from 313 K to 589 K. A.I.Ch.E. Symp.
Ser, 83, 97–118.
Iliuta, M. C., Iliuta, I., Landauer, O. M., and Thyrion, F. C. 1998. Salt effect of LiCl on
vapor-liquid equilibrium of the acetone-methanol system. Fluid Phase Equilibria,
149, 163–176.
Johnson, A. I., and Furter, W. F. 1957. Can. J. Technol., 35, 413.
Lee, L.L. 1997. A molecular theory of Setchenov’s salting out principle and application
in mixed-solvent electrolyte solutions. Fluid Phase Equilibria, 131, 67–82.
84
Thermodynamic Study of Ternary Refrigerant Equilibria
Libotean, S., Salavera, D., Valles, M., Esteve, X., and Coronas, A. 2007. Vapor-Liquid
Equilbrium of Ammonia-Lithium Nitrate-Water and Ammonia-Lithium Nitrate So-
lutions from (293.15 to 353.15)K. J. Chem. Eng. Data, 52(1050-1055).
Mejbri, K., and Bellagi, A. 2005. Modelling of the thermodynamic properties of the
water-ammonia mixture by three different approaches. International Journal of Re-
frigeration.
Meyer, E., Ermatchkov, V., Kamps, A. P., and Maurer, G. 2006. Simultaneous solubility
of sulphar dioxide and Ammonia in (salt-water) and enthalpy change upon dilution
of (Sulphur Dioxide+ammonia+salt+water) in (salt+water)(salt+ammoniaum sulpa-
het or Sosium sulpahet) Experimental Results and Model Predictions. Fluid Phase
Equilibria, 244(137-152).
Peters, R., Greb, O., Korinth, C., and Zimmermann, A. 1994. Vapor liquid equilibria in
the system NH
3
-H
2
O-LiBr. Part I: measurements in the range T= 303-423 K and P=
0.1-1.5 MPa. J. Chem. Eng. Data, 40(4), 769–74.
Polak, J., benjamin, C., and Lu, Y. 1975. Vapor-Liquid Equilibria in System Ammonia-
Water at 14.69 and 65 Psia. J. Chem. Eng. Data, 20(2).
Polikhronidi, N. G., Abdulagatov, I. M., Batyrova, R. G., and Stepanov, G. V. 2009. PVT
measurements of water-ammonia refrigerant mixture in the critical and supercritical
regions. International Journal of Refrigeration, 32, 1897–1913.
Renon, H., and M, Prausnitz J. 1969. Estimation of parameter for the NRTL equation for
exess Gibbs Energies of strongly nonideal liquid mixtures. Ind. Eng. Chem. Precess
Des. Dev., 8(3), 413–419.
Rousseau, R. W., Ashcraft, D. L., and Schoenborn, E. M. 1972. Salt Effect in Vapor-
Liquid Equilibria: Correlation of Alcohol-Water-Salt System. AIChE Journal,
18(4), 825–828.
Salavera, D., Chaudhari, S.K., Esteve, X., and Coronas, A. 2005. Vapor-Liquid Equilibria
of Ammonia-Water-Potassium Hydroxide and Ammonia-Water-Sodium Hydroxide
85
Thermodynamic Study of Ternary Refrigerant Equilibria
Solutions at Temperatures from (293.15 to 353.15) K. J. Chem. Eng. Data, 50,
471–476.
Smolen, T. M., Manley, D. B., and Poling, B. E. 1991. Vapor-Liquid Equlibrium data
for the ammonia-water system and its description with a modified cubic equation of
state. J. Chem. Eng. Data, 36(2), 202–208.
Syed, S., Rizvl, and Heidemann, R. A. 1987. Vapor-Liquid Equilibria in the Ammonia-
water system. J. Chem. Eng. Data, 32, 183–191.
Yuyuan, W., Yan C., and Tiehui, W. 2005. Experimental researches on characteristics of
vapor-liquid equilibriun of ammonia-water-LiBr system. International Journal of
refrigeration, 1–8.
Zimmermann, A., and Keller, J. U. 1989. VLE in the system water-ammonia-lithium
bromide. Fluid Phase Equilibria, 53, 229–234.
86
Synopsis
87

Sponsor Documents

Or use your account on DocShare.tips

Hide

Forgot your password?

Or register your new account on DocShare.tips

Hide

Lost your password? Please enter your email address. You will receive a link to create a new password.

Back to log-in

Close