

MCQOPTIONS
This section includes 50 Mcqs, each offering curated multiple-choice questions to sharpen your ENGINEERING SERVICES EXAMINATION (ESE) knowledge and support exam preparation. Choose a topic below to get started.
1. |
One ton of the refrigeration is |
A. | The standard unit used in refrigeration problems |
B. | The cooling effect produced by melting 1 ton of ice |
C. | The refrigeration effect to freeze 1 ton of water at 0°C into ice at 0°C in 24 hours |
D. | The refrigeration effect to produce 1 ton of ice at NTP conditions |
Answer» D. The refrigeration effect to produce 1 ton of ice at NTP conditions | |
2. |
The refrigerant used for absorption refrigerators working on heat from solar collectors is a mixture of water and |
A. | Carbon dioxide |
B. | Sulphur dioxide |
C. | Lithium bromide |
D. | R-12 |
Answer» D. R-12 | |
3. |
Highest pressure encountered in a refrigeration system should be |
A. | Critical pressure of refrigerant |
B. | Much below critical pressure |
C. | Much above critical pressure |
D. | Near critical pressure |
Answer» C. Much above critical pressure | |
4. |
In aircraft, air refrigeration Cycle is used because of |
A. | Low weight per tonne of refrigeration |
B. | High heat transfer rate |
C. | Low temperature at high altitudes |
D. | Higher coefficient of performance |
Answer» B. High heat transfer rate | |
5. |
Condensing temperature in a refrigerator is the temperature |
A. | Of cooling medium |
B. | Of freezing zone |
C. | Of evaporator |
D. | At which refrigerant gas becomes liquid |
Answer» E. | |
6. |
The pressure at the inlet of a refrigerant compressor is called |
A. | Suction pressure |
B. | Discharge pressure |
C. | Critical pressure |
D. | Back pressure |
Answer» B. Discharge pressure | |
7. |
Pick up the wrong statement. A refrigerant should have |
A. | Tow specific heat of liquid |
B. | High boiling point |
C. | High latent heat of vaporisation |
D. | Higher critical temperature |
Answer» C. High latent heat of vaporisation | |
8. |
Hydrogen is used in Electrolux refrigeration system so as to _________ the rate of evaporation of the liquid ammonia passing through the evaporator. |
A. | Equalize |
B. | Reduce |
C. | Increase |
D. | None of these |
Answer» D. None of these | |
9. |
If the evaporator temperature of a plant is lowered, keeping the condenser temperature constant, the h.p. of compressor required will be |
A. | Same |
B. | More |
C. | Less |
D. | More/less depending on rating |
Answer» C. Less | |
10. |
Which of the following refrigerant has the maximum ozone depletion potential in the stratosphere? |
A. | Ammonia |
B. | Carbon dioxide |
C. | Sulphur dioxide |
D. | Fluorine |
Answer» E. | |
11. |
In vapour compression cycle, the condition of refrigerant is saturated liquid |
A. | After passing through the condenser |
B. | Before passing through the condenser |
C. | After passing through the expansion throttle valve |
D. | Before entering the expansion valve |
Answer» B. Before passing through the condenser | |
12. |
The reduced ambient air cooling system has |
A. | One cooling turbine and one heat exchanger |
B. | One cooling turbine and two heat exchangers |
C. | Two cooling turbines and one heat exchanger |
D. | Two cooling turbines and two heat exchangers |
Answer» D. Two cooling turbines and two heat exchangers | |
13. |
The leaks in a refrigeration system using Freon are detected by |
A. | Halide torch which on detection produces greenish flame lighting |
B. | Sulphur sticks which on detection gives white smoke |
C. | Using reagents |
D. | Smelling |
Answer» B. Sulphur sticks which on detection gives white smoke | |
14. |
The process, generally used in winter air-conditioning to warm and humidity the air, is called |
A. | Humidification |
B. | Dehumidification |
C. | Heating and humidification |
D. | Cooling and dehumidification |
Answer» D. Cooling and dehumidification | |
15. |
One ton refrigeration corresponds to |
A. | 50 kcal/ min |
B. | 50 kcal/ hr |
C. | 80 kcal/ min |
D. | 80 kcal/ hr |
Answer» B. 50 kcal/ hr | |
16. |
During sensible heating of air _________ decreases. |
A. | Wet bulb temperature |
B. | Relative humidity |
C. | Dry bulb temperature |
D. | Specific humidity |
Answer» C. Dry bulb temperature | |
17. |
For proper refrigeration in a cabinet, if the temperature and vapour pressure difference between cabinet and atmosphere is high, then |
A. | Bigger cabinet should be used |
B. | Smaller cabinet should be used |
C. | Perfectly tight vapour seal should be used |
D. | Refrigerant with lower evaporation temperature should be used |
Answer» D. Refrigerant with lower evaporation temperature should be used | |
18. |
In a vapour compression system, the condition of refrigerant before passing through the condenser is |
A. | Saturated liquid |
B. | Wet vapour |
C. | Dry saturated vapour |
D. | Superheated vapour |
Answer» E. | |
19. |
Which of the following statement is wrong? |
A. | The performance of the vapour compression refrigerator varies considerably with both vaporising and condensing temperatures. |
B. | In vapour compression cycle, the useful part of the heat transfer is at the condenser. |
C. | In ammonia-hydrogen (Electrolux) refrigerator, no compressor, pump or fan is required. |
D. | The effect of under-cooling the liquid refrigerant is to decrease the coefficient of performance |
Answer» E. | |
20. |
The vapour pressure of refrigerant should be |
A. | Lower than atmospheric pressure |
B. | Higher than atmospheric pressure |
C. | Equal to atmospheric pressure |
D. | Could be anything |
Answer» C. Equal to atmospheric pressure | |
21. |
During humidification process, dry bulb temperature |
A. | Remains constant |
B. | Increases |
C. | Decreases |
D. | None of these |
Answer» B. Increases | |
22. |
The C.O.P of a refrigeration cycle with increase in evaporator temperature, keeping condenser temperature constant, will |
A. | Increase |
B. | Decrease |
C. | Remain unaffected |
D. | May increase or decrease depending on the type of refrigerant used |
Answer» B. Decrease | |
23. |
The wet bulb depression is zero when relative humidity is |
A. | Zero |
B. | 0.5 |
C. | 0.75 |
D. | 1.0 |
Answer» E. | |
24. |
At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant |
A. | Decreases |
B. | Increases |
C. | Remain same |
D. | Depends on other factors |
Answer» C. Remain same | |
25. |
During sensible cooling of air ________ decreases. |
A. | Wet bulb temperature |
B. | Relative humidity |
C. | Dry bulb temperature |
D. | Specific humidity |
Answer» D. Specific humidity | |
26. |
The moisture in a refrigerant is removed by |
A. | Evaporator |
B. | Safety relief valve |
C. | Dehumidifier |
D. | Driers |
Answer» E. | |
27. |
The refrigerant widely used in domestic refrigerators is |
A. | Ammonia |
B. | Carbon dioxide |
C. | Sulphur dioxide |
D. | R-12 |
Answer» E. | |
28. |
During dehumidification process, the relative humidity |
A. | Remains constant |
B. | Increases |
C. | Decreases |
D. | None of these |
Answer» D. None of these | |
29. |
Rick up the incorrect statement |
A. | Lithium bromide used in vapour absorption cycle is non volatile |
B. | Lithium bromide plant cant operate below 0°C |
C. | A separator is used in lithium bromide plant to remove the unwanted water vapour by condensing |
D. | Concentration of solution coming out of lithium bromide generator is more in comparison to that entering the generator |
Answer» D. Concentration of solution coming out of lithium bromide generator is more in comparison to that entering the generator | |
30. |
The centrifugal compressors are generally used for refrigerants that require |
A. | Small displacements and low condensing pressures |
B. | Large displacements and high condensing pressures |
C. | Small displacements and high condensing pressures |
D. | Large displacements and low condensing pressures |
Answer» E. | |
31. |
An important characteristic of absorption system of refrigeration is |
A. | Noisy operation |
B. | Quiet operation |
C. | Cooling below 0°C |
D. | Very little power consumption |
Answer» C. Cooling below 0°C | |
32. |
The condition of refrigerant after passing through the expansion or throttle valve, in a vapour compression system is |
A. | High pressure saturated liquid |
B. | Wet vapour |
C. | Very wet vapour |
D. | Dry vapour |
Answer» D. Dry vapour | |
33. |
Domestic refrigerator working on vapour compression cycle uses the following type of expansion device |
A. | Electrically operated throttling valve |
B. | Manually operated valve |
C. | Thermostatic valve |
D. | Capillary tube |
Answer» E. | |
34. |
The fluids used in Electrolux refrigerator are |
A. | Water and hydrogen |
B. | Ammonia and hydrogen |
C. | Ammonia, water and hydrogen |
D. | None of these |
Answer» D. None of these | |
35. |
The COP of a vapour compression plant in comparison to vapour absorption plant is |
A. | More |
B. | Less |
C. | Same |
D. | More/less depending on size of plant |
Answer» B. Less | |
36. |
The condition of refrigerant after passing through the condenser in a vapour compression system is |
A. | Saturated liquid |
B. | Wet vapour |
C. | Dry saturated vapour |
D. | Superheated vapour |
Answer» B. Wet vapour | |
37. |
In a lithium bromide absorption refrigeration system |
A. | Lithium bromide is used as a refrigerant and water as an absorbent |
B. | Water is used as a refrigerant and lithium bromide as an absorbent |
C. | Ammonia is used as a refrigerant and lithium bromide as an absorbent |
D. | None of the above |
Answer» C. Ammonia is used as a refrigerant and lithium bromide as an absorbent | |
38. |
The bank of tubes at the back of domestic refrigerator is |
A. | Condenser tubes |
B. | Evaporator tubes |
C. | Refrigerant cooling tubes |
D. | Capillary tubes |
Answer» B. Evaporator tubes | |
39. |
A human body feels comfortable when the heat produced by the metabolism of human body is equal to the |
A. | Heat dissipated to the surroundings |
B. | Heat stored in the human body |
C. | Sum of (A) and (B) |
D. | Difference of (A) and (B) |
Answer» D. Difference of (A) and (B) | |
40. |
Rating of a domestic refrigerator is of the order of |
A. | 0.1 ton |
B. | 5 tons |
C. | 10 tons |
D. | 40 tons |
Answer» B. 5 tons | |
41. |
In actual air-conditioning applications for R-12 and R-22, and operating at a condenser temperature of 40° C and an evaporator temperature of 5° C, the heat rejection factor is about |
A. | 1 |
B. | 1.25 |
C. | 2.15 |
D. | 5.12 |
Answer» C. 2.15 | |
42. |
The vapour compression refrigerator employs the following cycle |
A. | Rankine |
B. | Carnot |
C. | Reversed Rankine |
D. | Reversed Carnot |
Answer» E. | |
43. |
In a refrigeration system, the expansion device is connected between the |
A. | Compressor and condenser |
B. | Condenser and receiver |
C. | Receiver and evaporator |
D. | Evaporator and compressor |
Answer» D. Evaporator and compressor | |
44. |
Mass flow ratio of NH₃ in comparison to Freon-12 for same refrigeration load and same temperature limits is of the order ofa |
A. | 1: 1 |
B. | 1: 9 |
C. | 9: 1 |
D. | 1: 3 |
Answer» C. 9: 1 | |
45. |
The freezing point of sulphur dioxide is |
A. | -56.6°C |
B. | -75.2°C |
C. | -77.7°C |
D. | -135.8°C |
Answer» C. -77.7°C | |
46. |
Cooling water is required for following equipment in ammonia absorption plant |
A. | Condenser |
B. | Evaporator |
C. | Absorber |
D. | Condenser, absorber and separator (rectifier) |
Answer» E. | |
47. |
A reversible engine has ideal thermal efficiency of 30%. When it is used as a refrigerating machine with all other conditions unchanged, the coefficient of performance will be |
A. | 1.33 |
B. | 2.33 |
C. | 3.33 |
D. | 4.33 |
Answer» C. 3.33 | |
48. |
For obtaining high COP, the pressure range of compressor should be |
A. | High |
B. | Low |
C. | Optimum |
D. | Any value |
Answer» C. Optimum | |
49. |
The boiling point of ammonia is |
A. | -10.5°C |
B. | -30°C |
C. | -33.3°C |
D. | -77.7°C |
Answer» D. -77.7°C | |
50. |
Freon group of refrigerants are |
A. | Inflammable |
B. | Toxic |
C. | Non-inflammable and toxic |
D. | Nontoxic and non-inflammable |
Answer» E. | |