refrigiration

Question 1

refrigeration system sequence

Answer 1

1. compressor
2. condenser
3. expansion valve
4. evaporator

Question 2

state of compressor in cycle

Answer 2

HP, HT

Question 3

state of condenser in cycle

Answer 3

HP, HT

Question 4

state of expansion valve in cycle

Answer 4

LP, LT

Question 5

state of evaporator in cycle

Answer 5

LP, LT

Question 6

operation of a domestic refrigiraton plant

Answer 6

the cycle goes through 4 main components, the compressor as a superheated vapour and with high pressure, then it goes through a condenser which it remains as high pressure but changes to a liquid, it then reaches the expansion valve which changes it from hig to low pressure and also drops the temperature and finally the evaporator which gives the refrigerant a high temperature but low pressure

Question 7

indication of air in system

Answer 7

1. compressor overheating
2. high discharge pressure
3. small bubbles in sight glass
4. condenser pressure guage high reading

Question 8

indications of undercharge

Answer 8

1. low condenser guage reading
2. large bubbles in sight glass
3. compressor will be hot
4. performance will fall

Question 9

how is air removed from system

Answer 9

close condenser liquid outlet, with circulating water on, charge is pumper to the condenser and receiver.
the air will remain at the top and it is released by slackening the purge valve

Question 10

where is refrigirant added to the system

Answer 10

1. liquid line, before the drier

2. compressor suction side service stop valve

Question 11

how to add refrigerant

Answer 11

1. open solonoids
2. weigh cylinder
   3.connect cylinder to charging valve, purging air from the line.
3. Close outlet from condenser valve,
   check and not level of liquid
4. close compressor suction service stop valve
   6.open charging valve so refrigirant can flow
5. check liquid level
6. Close charging valve open condenser or receiver outlet valve
7. open compressor suction
8. check flow via sight glass