MCQOPTIONS
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MCQOPTIONS
This section includes 368 Mcqs, each offering curated multiple-choice questions to sharpen your Mechanical Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Latent heat of vaporization of a refrigerant ,at lower temperatures and pressures |
| A. | increase |
| B. | decreases |
| C. | remains constant |
| D. | unpredictable |
| Answer» B. decreases | |
| 2. |
An ideal refrigerant should have |
| A. | low latent heat of vaporization |
| B. | high critical temperature |
| C. | high boiling point |
| D. | high specific volume of vapour |
| Answer» C. high boiling point | |
| 3. |
The amount of heat absorbed by the system at low temperature is |
| A. | COP |
| B. | Refrigerating effect |
| C. | work done on the system |
| D. | refrigeration efficiency |
| Answer» C. work done on the system | |
| 4. |
Reversed carnot cycle comprises |
| A. | two isentropic processes and two adiabatic processes |
| B. | two isentropic processes and two isothermal processes |
| C. | two isentropic processes and two isobaric processes |
| D. | two isentropic processes and two isochoric processes |
| Answer» C. two isentropic processes and two isobaric processes | |
| 5. |
Two Carnot Refrigerators are employed, one for ice making and other for comfort cooling |
| A. | The COP of the refrigerator for ice making is higher than that for other |
| B. | The COP of the refrigerator for ice making is same as that for the other |
| C. | The COP of the refrigerator for ice making is lower than that for other |
| D. | The COP of Carnot refrigerator will depend on refrigerant used |
| Answer» D. The COP of Carnot refrigerator will depend on refrigerant used | |
| 6. |
Carnot refrigerator absorbs heat at -13 C and requires 1 kW for each 6.5 kW of heat absorbed, the COP and temperature of heat rejections respectively |
| A. | COP = 6.5, t = 27 C |
| B. | COP = 7.5, t = 27 C |
| C. | COP = 6.5, t = 30 C |
| D. | COP = 7.5, t = 37 C |
| Answer» B. COP = 7.5, t = 27 C | |
| 7. |
The dense air refrigeration system as compared to open air refrigeration system for same range of temperatures using Bell- Colemann cycle requires. |
| A. | Same power/Ton of Refrigeration |
| B. | Lower power/Ton of Refrigeration |
| C. | Higher power/Ton of Refrigeration |
| D. | Unpredictable Results. |
| Answer» C. Higher power/Ton of Refrigeration | |
| 8. |
The air craft system giving Lowest Dry Air Rated Turbine discharge temperature at supersonic cruising speeds of the plane, is |
| A. | Reduced ambient system of Refrigeration |
| B. | Boot-strap system of Refrigeration |
| C. | Regenerative system of Refrigeration |
| D. | Boot strap evaporative system of Refrigeration |
| Answer» E. | |
| 9. |
For very high speed planes cruising at Mach number 2.5 and above, the air craft refrigeration system recommended is |
| A. | Simple evaporative type |
| B. | Boot-strap type |
| C. | Regenerative type |
| D. | Boot strap evaporative type |
| Answer» E. | |
| 10. |
There are two cooling turbines in |
| A. | Reduced ambient system of Refrigeration |
| B. | Boot-strap system of Refrigeration |
| C. | Regenerative system of Refrigeration |
| D. | Boot strap evaporative system of Refrigeration |
| Answer» B. Boot-strap system of Refrigeration | |
| 11. |
There are two stages of compression of air in |
| A. | Reduced ambient system of Refrigeration |
| B. | Boot-strap system of Refrigeration |
| C. | Regenerative system of Refrigeration |
| D. | Simple evaporative system of Refrigeration |
| Answer» C. Regenerative system of Refrigeration | |
| 12. |
Co-efficient of performance of a Reversed Carnot cycle refrigerator working between higher temperature T2 and lower temperature T1 |
| A. | will increase with increase in T1 keeping T2 fixed |
| B. | will decrease with increase in T1 keeping T2 fixed |
| C. | will first increase with increase in T1 and then decrease with increase T1 keeping T2 fixed |
| D. | None of the above |
| Answer» B. will decrease with increase in T1 keeping T2 fixed | |
| 13. |
Bell-Colemann cycle comprises |
| A. | two isentropic processes and two adiabatic processes |
| B. | two isentropic processes and two isothermal processes |
| C. | two isentropic processes and two isobaric processes |
| D. | two isentropic processes and two isochoric processes |
| Answer» D. two isentropic processes and two isochoric processes | |
| 14. |
In Bell Colemann refrigerator for the same temperature range |
| A. | COP of dense air system is equal to COP of open air system |
| B. | COP of dense air system is lower than COP of open air system |
| C. | COP of dense air system is higher than COP of open air system |
| D. | COP of dense air system may be higher or lower than COP of open air system depending upon pressure ratio. |
| Answer» D. COP of dense air system may be higher or lower than COP of open air system depending upon pressure ratio. | |
| 15. |
The COP of Carnot Refrigerator is 3 and it produces 1 TR. The work that will be done is equal to |
| A. | 70 kJ/min |
| B. | 100 kJ/min |
| C. | 200 kJ/min |
| D. | 210 kJ/min |
| Answer» B. 100 kJ/min | |
| 16. |
The air craft system giving Lowest Dry Air Rated Turbine discharge temperature at supersonic cruising speeds of the plane, is |
| A. | Reduced ambient system of Refrigeration |
| B. | Boot-strap system of Refrigeration |
| C. | Regenerative system of Refrigeration |
| D. | Boot strap evaporative system of Refrigeration |
| Answer» E. | |
| 17. |
A Bell-Colemann cycle is |
| A. | reversed Carnot Cycle |
| B. | reversed Joule Cycle |
| C. | reversed Rankine cycle |
| D. | None of the above |
| Answer» C. reversed Rankine cycle | |
| 18. |
A reversible refrigerator working between two fixed temperatures |
| A. | has the same COP whatever the working substance |
| B. | has its COP increased for working substance with high enthalpy of evaporation |
| C. | has its COP increased for working substance with higher specific heats |
| D. | none of above |
| Answer» B. has its COP increased for working substance with high enthalpy of evaporation | |
| 19. |
Heat is absorbed by the refrigerant, during vapour compression refrigeration cycle in |
| A. | Compressor |
| B. | Condenser |
| C. | Evaporator |
| D. | Throttle valve |
| Answer» D. Throttle valve | |
| 20. |
Munters Platen system of refrigeration is |
| A. | Vapour absorption system with ammonia and water |
| B. | Vapour compression system with ammonia as working substance |
| C. | Electrolux system with Hydrogen, ammonia and water as working substances |
| D. | none of the above |
| Answer» D. none of the above | |
| 21. |
Which of the following can be measured by a sling psychrometer? |
| A. | Wet bulb temperature |
| B. | Dry bulb as well as wet bulb temperatures |
| C. | Specific humidity |
| D. | Absolute humidity |
| Answer» C. Specific humidity | |
| 22. |
In a simple saturated vapour compression cycle, the refrigerant is in superheated condition |
| A. | before entering compressor |
| B. | before entering condenser |
| C. | before entering throttle valve |
| D. | before entering evaporator |
| Answer» C. before entering throttle valve | |
| 23. |
The order in which main components of vapour compression refrigeration system are used is |
| A. | compressor-evaporator-condenser-throttle valve |
| B. | compressor-condenser-evaporator-throttle valve |
| C. | compressor-throttle valve- evaporator-condenser |
| D. | compressor-condenser- throttle valve- evaporator |
| Answer» E. | |
| 24. |
Sub-cooling is a process of cooling the refrigerant in vapour compression refrigeration system |
| A. | after compression |
| B. | before compression |
| C. | before Throttling |
| D. | none of the above |
| Answer» D. none of the above | |
| 25. |
For simple saturated vapour compression refrigeration cycle operating between 5 C and 40 C, and the refrigerants being R-11, R-12, R-717 and R-22, the compressor displacement per min per ton of refrigeration is highest for |
| A. | R-11 |
| B. | R-12 |
| C. | R-717 |
| D. | R-22 |
| Answer» B. R-12 | |
| 26. |
Co-efficient of performance of vapour absorption refrigeration system as compared to that for vapour compression refrigeration system is |
| A. | more |
| B. | less |
| C. | may be more or less |
| D. | un - predictable |
| Answer» C. may be more or less | |
| 27. |
In vapour absorption refrigeration system heating in generator is done at 100 C, refrigeration in evaporator at 10 C and cooling by cooling water in condenser at 30 C. The (COP)max is |
| A. | 0.5 |
| B. | 0.35 |
| C. | 2 |
| D. | in sufficient data |
| Answer» C. 2 | |
| 28. |
Following results are tabulated for vapour compression refrigeration cycle.Enthalpy at suction = 190 kJ/kgEnthalpy at discharge from compressor = 210 kJ/kgEnthalpy at exit from condenser = 80 kJ/kgCOP of cycle would be |
| A. | 3.5 |
| B. | 4.5 |
| C. | 5.5 |
| D. | 6.5 |
| Answer» D. 6.5 | |
| 29. |
Work of compression of the fluid in vapour absorption refrigeration system as compared to that for vapour compression refrigeration system is |
| A. | les |
| B. | more |
| C. | may be more or less |
| D. | un - predictable |
| Answer» B. more | |
| 30. |
With reciprocating compressor in vapour compression refrigeration system, wet compression is not desirable because |
| A. | liquid trapped up in the head of cylinder may damage the compressor valves |
| B. | COP of the cycle decreases |
| C. | volumetric efficiency of compressor decreases |
| D. | mass flow rate per ton of refrigerant increases |
| Answer» B. COP of the cycle decreases | |
| 31. |
The function of compressor in vapour compression refrigeration system is performed in vapour absorption system by |
| A. | generator |
| B. | absorber |
| C. | generator, absorber and liquid pump |
| D. | absorber and liquid pump |
| Answer» D. absorber and liquid pump | |
| 32. |
In vapour compression refrigeration cycle the following data is available Heat rejected in condenser = 65 KW Work done in compressor = 10 kw, then COP( refrigerator) is |
| A. | 4.5 |
| B. | 5.5 |
| C. | 6.5 |
| D. | not possible to find with the given data |
| Answer» C. 6.5 | |
| 33. |
Heat is rejected by the refrigerant, during vapour compression refrigeration cycle in |
| A. | Compressor |
| B. | Condenser |
| C. | Evaporator |
| D. | Throttle valve |
| Answer» C. Evaporator | |
| 34. |
Electrolux system of refrigeration has |
| A. | only one liquid pump |
| B. | only two liquid pumps |
| C. | no liquid pump |
| D. | none of the above |
| Answer» D. none of the above | |
| 35. |
The widely used refrigerant in domestic refrigerators is |
| A. | Carbon-dioxide |
| B. | Sulphur dioxide |
| C. | Freon-12 |
| D. | Ammonia |
| Answer» D. Ammonia | |
| 36. |
Electrolux refrigerators has the following working substances |
| A. | Hydrogen |
| B. | Ammonia and Hydrogen |
| C. | Ammonia and water |
| D. | Ammonia, hydrogen and water |
| Answer» E. | |
| 37. |
Electrolux refrigerators is |
| A. | Vapour compression refrigerator with one compressor |
| B. | vapour absorption refrigerator with no pump |
| C. | vapour absorption refrigerator with one aqua pump |
| D. | None of the above |
| Answer» C. vapour absorption refrigerator with one aqua pump | |
| 38. |
Heat is absorbed by a refrigerant, during a refrigeration cycle in a |
| A. | condenser |
| B. | evaporator |
| C. | compressor |
| D. | throttle valve |
| Answer» C. compressor | |
| 39. |
In a flooded type of Evaporator which of the following types of expansion device is utilized |
| A. | Float Valve |
| B. | Thermostatic device |
| C. | Capillary tube |
| D. | Self actuated expansion valve |
| Answer» B. Thermostatic device | |
| 40. |
Freon group refrigerants are |
| A. | toxic |
| B. | inflamma |
| C. | nontoxic and inflammable |
| D. | non- toxic & non-inflammable |
| Answer» E. | |
| 41. |
Freon group of refrigerants |
| A. | toxic |
| B. | inflammable |
| C. | non-toxic and non-inflammable |
| D. | highly toxic and inflammable |
| Answer» D. highly toxic and inflammable | |
| 42. |
Which of the following refrigerants has the lowest boiling point? |
| A. | Freon-12 |
| B. | Carbon-dioxide |
| C. | Ammonia |
| D. | Sulphur dioxide |
| Answer» C. Ammonia | |
| 43. |
Which of the following system can be called as mechanical system of refrigeration |
| A. | Vapour absorption system |
| B. | Vapour compression system |
| C. | Steam jet refrigeration system |
| D. | None of the above |
| Answer» C. Steam jet refrigeration system | |
| 44. |
.In a psychrometric chart, the vertical lines parallel to the ordinate indicate |
| A. | Dry bulb Temperature |
| B. | Wet bulb Temperature |
| C. | Specific humidity |
| D. | Enthalpy of saturation |
| Answer» B. Wet bulb Temperature | |
| 45. |
The Refrigerant commonly used in commercial ice plants is |
| A. | Carbon-dioxide |
| B. | Air |
| C. | Ammonia |
| D. | Freon-12 |
| Answer» D. Freon-12 | |
| 46. |
What is the effect of frost on the cooling coils of the evaporator of refrigeration system |
| A. | It reduces the life of cooling coils |
| B. | It increases the compressor pressure |
| C. | It makes the compressor run for comparatively short runs |
| D. | It acts as the insulator and decreases the heat transfer rate |
| Answer» E. | |
| 47. |
The refrigerant with highest critical pressure is |
| A. | Carbon dioxide |
| B. | Ammonia |
| C. | Freon-11 |
| D. | Freon-22 |
| Answer» C. Freon-11 | |
| 48. |
For simple saturated vapour compression refrigeration cycle operating between 5 C and 40 C, and the refrigerants being R-11, R-12, R-717 and R-22, the evaporator pressure is highest for |
| A. | R-11 |
| B. | R-12 |
| C. | R-717 |
| D. | R-22 |
| Answer» E. | |
| 49. |
For simple saturated vapour compression refrigeration cycle operating between 5 C and 40 C, and the refrigerants being R-11, R-12, R-717 and R-22, the evaporator pressure is lowest for |
| A. | R-11 |
| B. | R-12 |
| C. | R-717 |
| D. | R-22 |
| Answer» B. R-12 | |
| 50. |
The refrigerant leaving throttle valve is |
| A. | saturated liquid |
| B. | saturated vapour |
| C. | superheated vapour |
| D. | fraction as saturated vapour and remainder as liquid |
| Answer» E. | |