Vapour Compression

Published on January 2017 | Categories: Documents | Downloads: 26 | Comments: 0 | Views: 217
of 9
Download PDF   Embed   Report

Comments

Content

(C)DR.A.M.SURENDRA KUMAR

1

VAPOUR COMPRESSION REFRIGERATION SYSTEM

(C)DR.A.M.SURENDRA KUMAR

2

(C)DR.A.M.SURENDRA KUMAR 3

(C)DR.A.M.SURENDRA KUMAR

5

RESULTS OF FIRST AND SECOND LAW ANALYSIS FOR STEADY-FLOW

COMPONENT

PROCESS s = Const.

FIRST LAW RESULT

1 2 3 4

Compressor

 m  (h2  h1 ) W in

 0 W net Condenser P = Const Expansion Valve s > 0
Evaporator P = Const

 m  (h2  h3 ) Q H

h4  h3
 m  (h1  h4 ) Q L

COPR  COPHP 

 Q h h L  1 4  W h2  h1 net , in  Q h h H  2 3  Wnet ,in h2  h1
(C)DR.A.M.SURENDRA KUMAR 6

(C)DR.A.M.SURENDRA KUMAR

7

P-H CHART

(C)DR.A.M.SURENDRA KUMAR

8

MERITS & DEMERITS OF VAPOUR SYSTEM OVER AIR REFRIGERATION SYSTEM

• MERITS:
1. C.O.P. is quite high as the working of the cycle is very near to
that of reversed Carnot cycle.

2. When used on ground level the running cost of vapour
compression refrigeration system is only 1/5 of air refrigeration system. 3. For the same refrigeration effect the size of the evaporator is

smaller.
4. The required temperature of the evaporator can be achieved simply by adjusting the throttle valve of the same unit.

• DEMERITS
• 1. Initial cost is high. • 2. the major disadvantages are


• •

a) Inflammability
b) Leakage of vapours c) Toxity.

(C)DR.A.M.SURENDRA KUMAR

11

VAPOUR COMPRESSION REFRIGERATION SYSTEM ON T-S.DIAGRAM

EFFECT OF SUCTION & DELIVERY PRESSURE

EFFECT OF SUPERHEATING & SUBCOOLING OF LIQUID

LIQUID- VAPOUR HEAT EXCHANGER

EFFECT OF CONDENSING & EVAPORATING TEMPERATURE ON C.OP & REFRIGERATING EFFECT

(C)DR.A.M.SURENDRA KUMAR

17

EFFECT OF CONDENSER WATER TEMPERATURE ON POWER

(C)DR.A.M.SURENDRA KUMAR

18

PULL –DOWN CHARACTRISTCS

• PURPOSE OF THE TEST – COMPARE THE VALUES FOR DIFFERENT REFRIGERATORS FOR DIFFERENT REFRIGERENTS • TESTING OF REFRIGERATORS ACCORDING TO ISI SPECIFICATIONS • ENVIORNMENT TEMPERATURE – MAINTAINED AT 430C. • NO-LOAD TEST • ADJUST THERMOSTAT –CABNET TEMP. 70C. • PURPOSE: • FIND PULL –DOWN PERIOD • NO LOAD POWER CONSUMPTION • % RUNNING TIME • PULL –DOWN PERIOD : TIME REQUIRED TO REACH THE SPECIFIED TEMP. INSIDE THE CABNET AFTER SWITCHING ON THE UNIT.

Ice making time test
• For this test: • Stable operating conditions after Pull-down test • Quantity of 0.5 kg of water at 30 10C in std tray – kept in the freezer • Time for each “ON” and “OFF” is noted. • After specified time of 3 hrs., ice tray is examined for the formation of ice. • Running time of the unit during 3 hrs of operation is obtained from DAS • DAS –to monitor ÖN-OFF cycle. • This running time of the unit is the ice making time. • For Freon -12 refrigerator: • • pull-down period – 90 min for 160L capacity ice making time – 125 min.
(C)DR.A.M.SURENDRA KUMAR 20

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