Refrigeration & Air-Conditioning Practice Set-1

May 16, 2021

Show paginator

Hide paginator

25%

Page 1 of 4

1. The leaks in a refrigeration system using Freon are detected by

Using reagents

Smelling

Halide torch which on detection produces greenish flame lighting

Sulphur sticks which on detection gives white smoke

2. For air conditioning the operation theater in a hospital, the percentage of outside air in the air supplied is

100

Zero

3. Allowable pressure on high pressure side or ammonia absorption system is of the order of

56 bars

Slightly above atmospheric pressure

24 bars

Atmospheric pressure

4. Which of the following statement is correct?

In vapour absorption refrigerator, the compression of refrigerant is avoided.

Sub-cooling can be achieved by circulating more quantity of cooling water through the condenser.

All of these

In vapour compression refrigeration, the vapour is drawn in the compressor cylinder during its suction stroke and is compressed adiabatically during the compression stroke.

5. The C.O.P. of a Carnot refrigerator in winter will be _________ as compared to C.O.P. in summer.

Lower

Same

None of these

Higher

6. Absorption system normally uses the following refrigerant

CO2

Ammonia

Freon-11

Freon-22

7. Under cooling in a refrigeration cycle

C.O.P remains unaltered

Increases C.O.P

Other factors decide C.O.P

Decreases C.O.P

8. During sensible cooling of air ________ decreases.

Relative humidity

Dry bulb temperature

Wet bulb temperature

Specific humidity

9. Chaperon equation is a relation between

Temperature and enthalpy

Specific volume and enthalpy

Temperature, pressure, specific volume and enthalpy

Temperature, pressure and enthalpy

10. Pick up the incorrect statement

Lithium bromide used in vapour absorption cycle is non volatile

Concentration of solution coming out of lithium bromide generator is more in comparison to that entering the generator

Lithium bromide plant can't operate below 0°C

A separator is used in lithium bromide plant to remove the unwanted water vapour by condensing

Page 2 of 4

11. The reduced ambient air cooling system has

One cooling turbine and one heat exchanger

One cooling turbine and two heat exchangers

Two cooling turbines and two heat exchangers

Two cooling turbines and one heat exchanger

12. At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant

Depends on other factors

Increases

Remain same

Decreases

13. Domestic refrigerator working on vapour compression cycle uses the following type of expansion device

Electrically operated throttling valve

Manually operated valve

Capillary tube

Thermostatic valve

14. The fluids used in Electrolux refrigerator are

Ammonia and hydrogen

Ammonia, water and hydrogen

Water and hydrogen

None of these

15. The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure, is called

Degree of saturation

Relative humidity

Absolute humidity

Humidity ratio

16. During humidification process, __________ increases.

Relative humidity

Wet bulb temperature

Dry bulb temperature

Specific humidity

17. The condition of refrigerant after passing through the expansion or throttle valve, in a vapour compression system is

High pressure saturated liquid

Dry vapour

Very wet vapour

Wet vapour

18. The COP of a vapour compression plant in comparison to vapour absorption plant is

Less

More/less depending on size of plant

Same

19. The wet bulb depression is zero when relative humidity is

1.0

Zero

0.75

0.5

20. In vapour compression cycle using NH₃ as refrigerant, initial charge is filled at

Delivery of compressor

Suction of compressor

Low pressure side near receiver

High pressure side close to receiver

Page 3 of 4

21. In vapour compression cycle, the condition of refrigerant is saturated liquid

After passing through the condenser

After passing through the expansion throttle valve

Before entering the expansion valve

Before passing through the condenser

22. Which of the following statement is wrong?

The performance of the vapour compression refrigerator varies considerably with both vaporising and condensing temperatures.

In ammonia-hydrogen (Electrolux) refrigerator, no compressor, pump or fan is required.

The effect of under-cooling the liquid refrigerant is to decrease the coefficient of performance.

In vapour compression cycle, the useful part of the heat transfer is at the condenser.

23. During humidification process, dry bulb temperature

Remains constant

None of these

Decreases

Increases

24. For proper refrigeration in a cabinet, if the temperature and vapour pressure difference between cabinet and atmosphere is high, then

Perfectly tight vapour seal should be used

Refrigerant with lower evaporation temperature should be used

Bigger cabinet should be used

Smaller cabinet should be used

25. An important characteristic of absorption system of refrigeration is

Very little power consumption

Noisy operation

Cooling below 0°C

Quiet operation

26. The centrifugal compressors are generally used for refrigerants that require

Small displacements and low condensing pressures

Small displacements and high condensing pressures

Large displacements and low condensing pressures

Large displacements and high condensing pressures

27. Where does the lowest temperature occur in a vapour compression cycle?

Expansion valve

Compressor

Condenser

Evaporator

28. The refrigerant widely used in domestic refrigerators is

R-12

Ammonia

Carbon dioxide

Sulphur dioxide

29. The C.O.P of a refrigeration cycle with increase in evaporator temperature, keeping condenser temperature constant, will

Increase

Decrease

Remain unaffected

May increase or decrease depending on the type of refrigerant used

30. In a vapour compression system, the condition of refrigerant before passing through the condenser is

Saturated liquid

Superheated vapour

Wet vapour

Dry saturated vapour

Page 4 of 4

31. In a refrigeration cycle, the flow of refrigerant is controlled by

Expansion valve

Compressor

Evaporator

Condenser

32. The process, generally used in winter air-conditioning to warm and humidity the air, is called

Cooling and dehumidification

Heating and humidification

Dehumidification

Humidification

33. The temperature of air recorded by a thermometer, when it is not affected by the moisture present in the air, is called

Dew point temperature

Wet bulb temperature

Dry bulb temperature

None of these

34. The moisture in a refrigerant is removed by

Dehumidifier

Safety relief valve

Evaporator

Driers

35. During sensible heating of air _________ decreases.

Relative humidity

Wet bulb temperature

Specific humidity

Dry bulb temperature

36. One ton refrigeration corresponds to

50 kcal/ hr

50 kcal/ min

80 kcal/ hr

80 kcal/ min

37. The vapour pressure of refrigerant should be

Lower than atmospheric pressure

Higher than atmospheric pressure

Equal to atmospheric pressure

Could be anything

38. In a domestic vapour compression refrigerator, the refrigerant commonly used is

R-12

CO₂

Ammonia

All of these

39. During dehumidification process, the relative humidity

Decreases

None of these

Increases

Remains constant

40. The colour of the flame of halide torch, in case of leakage of Freon refrigerant, will change to

Orange

Bright green

Red

Yellow

Share this Now with Friends:

Anm"al dig f"or att fa 100 USDT says:
March 19, 2026 at 3:53 pm
Can you be more specific about the content of your article? After reading it, I still have some doubts. Hope you can help me.
registrera dig f"or binance says:
April 9, 2026 at 5:29 pm
Your point of view caught my eye and was very interesting. Thanks. I have a question for you.

Refrigeration & Air-Conditioning Practice Set-1

Related

2 Responses

Leave a ReplyCancel reply

Secured Payments

Protection