MULTIPLE CHOICE QUESTIONS ON REFRIGERATION AND AIR CONDITIONING

1-Which of the following refrigerant has lowest freezing temperature?

(A) Carbon dioxide

(B) Ammonia

(C) Freon-12

(D) Freon-22

(Ans: D)

2-The working fluid in Bell Coleman cycle is

(A) Freon-12

(B) Carbon dioxide

(C) Ammonia

(D) Air

(Ans: D)

3-In a vapour compression system, the compression of refrigerant follows the law

(A) PVr = C

(B) PV = C

(C) PVn = C

(D) None of the above

(Ans: C)

4-The dry bulb temperature lines of psychometric chart are

(A) Vertical

(B) Horizontal

(C) Inclined

(D) Curved

(Ans: A)

5-When the lower temperature is fixed, COP of a refrigerating machine can be improved by

(A) operating the machine at higher speeds

(B) operating the machine at lower speeds

(C) raising the higher temperature

(D) lowering the higher temperature

(Ans: D)

6-Evaporative air-cooler is used effectively when

(A) dry bulb temperature is very close to the wet bulb temperature

(B) dry bulb temperature is high and relative humidity is high

(C) dry bulb temperature is low and relative humidity is high

(D) dry bulb temperature is high and the relative humidity is low

(Ans: D)

7-Refrigerant Freon 12 belongs to

(A) methane family

(B) ethane family

(C) ketone family

(D) aldehyde family

(Ans: A)

8-Sometimes refrigerant plants use cooling towers. The water cooled in these towers is used

(A) for defrosting evaporator coils

(B) to cool compressor cylinder only

(C) to cool the evaporator coils

(D) to cool refrigerant in condenser

(Ans: D)

9-The statements concern Psychometric chart.

I-Constant relative humidity lines are uphill straight lines to the right

II-Constant wet bulb temperature lines are downhill straight lines to the right

III-Constant specific volume lines are downhill straight lines to the right

IV-Constant enthalpy lines are coincident with constant wet bulb temperature lines

Which of the statements are correct?

(A) II and II

(B) I and II

(C) I and III

(D) II and IV

(Ans: D)

10-In S.I. unit, one tonne of refrigeration is equal to

(A) 110 kJ/min

(B) 210 kJ/min

(C) 50 kJ/min

(D) non of the above

(Ans: B)

11-Subcooling occurs when the vapour

(A) has high latent heat

(B) removes sensible heat from refrigerant

(C) has low latent heat

(D) has high thermal conductivity

(Ans: B)

12-The refrigerant used in vapour absorption refrigerator is

(A) Freon-12

(B) Ammonia

(C) CO2

(D) Aqua-ammonia

(Ans: D)

13-In a window air conditioner, the expansion device used is

(A) Capillary tube

(B) Thermostatic expansion valve

(C) Automatic expansion valve

(D) Float valve

(Ans: A)

14-Formula for R134a refrigerant is

(A) CH Cl F2

(B) C2 Cl3 F3

(C) C2 Cl2 F4

(D) C2 H2 F4

(Ans: D)