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Saturday, 8 August 2015

Refrigeration and Air Conditioning - Multiple Choice Questions

Refrigeration and Air Conditioning - Multiple Choice Questions Points : mcqs, refrigeration and air conditioning multiple choice questions answers with answer key, refrigeration and air conditioning objective type question answers, absorption & refrigeration multiple choice questions answers, steam jet refrigeration system multiple choice questions answers, air washer multiple choice questions answers, screw compressor multiple choice questions answers, commercial air conditioning multiple choice questions answers, humidifiers and dehumidifier multiple choice questions answers, ice plants multiple choice questions answers 1. Steam jet refrigeration cycle employs a compressor device called.
a) vapor compressor
b) liquid pump
c) steam ejector

2. The load control in steam jet refrigeration cycle is obtained by
a) using multiple parallel ejector
b) increasing the mass flow rate of motive steam through nozzles

3. The cop of steam refrigeration cycle is of the order of.
a) 3 to4
b) 0.5 to 0.8
c) none of the above

4. The pressure maintained in the evaporator of steam jet refrigeration system depends upon application that is approximately
a) 1 bar to 2 bar
b) 0.012 bar to 0.013 bars
c) 5 bar to 6 bars

5. In a steam jet system two types of evaporator systems are used
a) Open chilled water system and closed chilled water system
b) Dry type and flooded type

6. In a steam jet system ________ is used as refrigerant.
a) ammonia
b) lithium bromide
c) water

7. In a steam jet system evaporation of the water takes places in the
a) steam ejector
b) condenser
c) flash tank

8. The steam jet cycle requires ______ moving mechanical component.
a) one
b) two
c) no

9. In steam jet system, steam supply should be free from suspended or dissolved solids carry over from the boiler otherwise nozzle may plug.
a) diffuses
b) nozzle

10. The volume rate of the flow of refrigerant per ton of refrigeration in steam jet refrigeration cycle as compared to that for R-12 vapor compression system is
a) very low
b) very high
c) practically the same

11. The wet bulb temperature of air whose relative humidity is 100% is
a) less than dew point temperature
b) equal to dew point temperature
c) greater than dry bulb temperature

12. The wet bulb temperature of air whose relative humidity is 100 % is
a) less than dry bulb temperature
b) equal to dry bulb temperature
c) may be more or less depending upon humidity ratio

13. Stream of moist air at bulb temperature of’ 35°C and dew point temperature of 25°C passes through a water shower (air washer) whose temperature is maintained at 20°C. The stream will undergo a process of
a) cooling and humidification
b) sensible cooling
c) cooling and dehumidification

14. Air washer equipment is effective in the removal of certain types of ____ from the air.
a) odors and dirt
b) noise
c) smoke and grease

15. ____ plates are installed at the outlet of the air washer to prevent droplets of water from being carried away from the air.
a) electrolytic
b) eliminator

16. High boiling points refrigerants are preferably suited for
a) reciprocating compressors
b) centrifugal compressors
c) small screw type compressors

17. Low boiling point refrigerant are preferably suited for
a) reciprocating compressors
b) large centrifugal compressors
c) large axial flow rotary compressors

18. The oil separator is incorporated in vapor compression refrigerant system
a) between evaporator and compressor
b) between compressor and condenser
c) between expansion valve and evaporator

19. Centrifugal refrigeration compressors are particularly well suited to direct steam turbine drive because of their
a) high cost
b) high operating speed
c) low operating speed

20. In a centrifugal chiller, during the cycle the refrigerant is returned to the ____ through afloat valve assembly
a) gas, cooler
b) liquid condenser
c) liquid, cooler

21. In a centrifugal refrigeration cycle, the refrigerant _______ passes into the condenser _______.
a) liquid, shell
b) vapor, shell
c) liquid, tubes

22. In centrifugal refrigeration cycle the refrigerant gas is condensed by giving up its latent heat to the condenser water which
a) flows around the outside of the tube
b) passes through the tube
c) none of the above

23. For simple saturated vapor compression, the refrigerant cycle operates between 5°C and 40°C and the refrigerants being R-11, R-12, R-717 and R-22 the evaporator pressure is the highest for _____.
a) R-11
b) R-12
c) R-717
d) R-22

24. Sub cooling is a process of cooling the refrigerant in vapor compression system ______.
a) after compression
b) before compression
c) before refrigerant control
d. none of the above

25. During the compression process there is ________ in heat content of the refrigerant gas characteristic of_________ gases.
a) increase, some
b) decrease, all
c) increase all

26. Dry evaporator is one which
a) the exit, from evaporator is dry saturated refrigerant
b) the exit from evaporator is superheated refrigerant
c) the exit from evaporator has refrigerant with high dryness fraction
d) the inlet to the evaporator has refrigerant with some dryness fraction

27. Flooded evaporator has to be fitted with
a) accumulator
b) float valve
c) liquid eliminator
d) liquid eliminator
e) all of the above

28. In a liquid chiller when the liquid to be chilled is in the shell and refrigerant flows n the tubes, it is fitted with
a) low side float control
b) high side float control
c) thermostatic expansion valve
d) none of the above

29. The direct expansion coil evaporator is a
a) flooded type evaporator
b) dry type evaporator
c) wet type evaporator
d) none of the above

30. A pump which the pressure is developed principally by the action of centrifugal force is called
a) rotary pump
b) reciprocating pump
c) centrifugal pump
d) none of the above

31. When Installing a natural draft cooling tower
a) location of the tower
b) preparation of foundation blocks
c) installation of water piping and pump
d) all of the above

32. In a three evaporator and single compressor and condenser system the evaporators are maintained at 10° C and condenser at 40° C with loads of the evaporator being 10 tons for the first, 20 tons for the second and 30 tons for the third. The mass flow, rate of refrigerants will be
a) m1; m2; m3; 1:1:1
b) m1; m2; m3; 1:1:2
c) m1; m2; m3; 3:2:1

33. The evaporative condenser combines the advantage of a _______ and a condenser in one unit
a) cooling coil
b) tower
c) none of the above

34. In forced draft cooling towers, the discharge of air should blow in the _____ direction as the prevailing wind.
a) opposite direction
b) same direction
c) both direction

35. An open hydronic system exposed to air will have effect on metals.
a) positive
b) negative
c) corrosive

36. A humidifier moisture to the circulating air in the system.
a) Removes
b) adds

37. A de-humidifier______ moisture from the circulating air in the system.
a) adds
b) removes

38. An electric de-humidifier removes moisture from the air by passing the air over
a) condenser coil
b) cooling coil

39. An ________ de-humidifier operates on the refrigeration principle.
a) pan type
b) electric type

40. A __________ is a central device actuated by a change in humidity and is used for automatic control of relative humidity.
a) low pressure cut-out
b) humidistat

41. Freezing tanks in an ammonia ice plant are made up of materials such as _______, _______ or _______.
a) copper, wood, aluminum
b) brass, nickel, lead
c) wood, steel, concrete

42. _________ freezing tanks used in ice plants have relatively short life and are subjected to leakages.
a) steel
b) copper
c) wood

43. In ammonia ice plants, the freezing tanks are made of _____ coated with water proof paint are preferred.
a) aluminium
b) steel
c) wood

44. ________ type of evaporator is used in ammonia ice plants.
a) fins and tube
b) shell and tube
c) hearing bone

45. Ammonia as a refrigerant has _____ volumetric displacement.
a) high
b) low
c) no

46. Ammonia as a refrigerant has _____ efficiency.
a) high
b) low
c) no

47. Ammonia refrigerant has _______ weight of liquid circulated per ton of refrigeration.
a) low
b) high

48. For ice plants of vapor compression system using ammonia refrigerant, the material of the pipes are
a) copper and brass
b) iron and steel
c) copper and steel

49. The _____ used in a brine cooler is to circulate the brine to facilitate the conduction and transfer of heat.
a) fan
b) blower
c) agitator

50. In ice plant _____ refrigerant is most commonly used.
a) freon 11
b) ammonia
c) freon22

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