260 Important Refrigeration And Air Conditioning MCQ Question and Answer | PDF Free Download
1.Nusselt number (NN) is given by
- ANN = hl/k
- BNN = μ cp/k
- CNN = ρ V l /μ
- DNN = V²/t.cp
2.In case of sensible heating of air, the coil efficiency is given by (where B.P.F. = Bypass factor)
- AB.P.F. – 1
- B1 - B. P.F.
- C1/ B.P.F.
- D1 + B.P.F.
3.The undesirable property of a refrigerant is
- ANon-toxic
- BNon-flammable
- CNon-explosive
- DHigh boiling point
4.The desirable property of a refrigerant is
- ALow boiling point
- BHigh critical temperature
- CHigh latent heat of vaporization
- DAll of these
5.The operating pressure for refrigerating units using R-12 as a refrigerant is
- A2 bar
- B8 bar
- C15 bar
- D30 bar
6.Cooling water is required for following equipment in ammonia absorption plant
- ACondenser
- BEvaporator
- CAbsorber
- DCondenser, absorber and separator (rectifier)
7.The coefficient of performance of a domestic refrigerator is ________ as compared to a domestic air-conditioner.
- ASame
- BLess
- CMore
- DNone of these
8.In aqua ammonia and Lithium bromide water absorption refrigeration systems, the refrigerants are respectively
- AWater and water
- BWater and lithium bromide
- CAmmonia and lithium bromide
- DAmmonia and water
9.In order to cool and dehumidify a stream of moist air, it must be passed over the coil at a temperature
- AWhich lies between the dry bulb and wet bulb temperatures of the incoming stream
- BWhich lies between the wet bulb and dew point temperatures of the incoming stream
- CWhich is lower than the dew point temperature of the incoming stream
- DOf adiabatic saturation of incoming stream
10.During heating and dehumidification process, dry bulb temperature
- ARemains constant
- BIncreases
- CDecreases
- DNone of these
11.During cooling and dehumidification, dry bulb temperature
- ARemains constant
- BIncreases
- CDecreases
- DNone of these
12.In a domestic vapour compression refrigerator, the refrigerant commonly used is
- ACO
- BAmmonia
- CR-12
- DAll of these
13.In refrigerators, the temperature difference between the evaporating refrigerant and the medium being cooled should be
- AHigh, of the order of 25°
- BAs low as possible (3 to 11°C)
- CZero
- DAny value
14.The minimum temperature to which water can be cooled in a cooling tower is
- ADew point temperature of air
- BWet bulb temperature of air
- CDry bulb temperature of air
- DAmbient air temperature
15.Air refrigeration cycle is used in
- ADomestic refrigerators
- BCommercial refrigerators
- CAir conditioning
- DGas liquefaction
16.A refrigeration cycle operates between condenser temperature of + 27°C and evaporator temperature of -23°C. The Carnot coefficient of performance of cycle will be
- A0.2
- B1.2
- C5
- D6
17.The bypass factor (B. P. F.) in case of sensible heating of air is (Where td₁ = Dry bulb temperature of air entering the heating coil, td₂ = Dry bulb temperature of air leaving the heating coil, and td₃ = Dry bulb temperature of heating coil)
- A(td₂ - td₃)/(td₃ - td₁)
- B(td₃ - td₂)/(td₃ - td₁)
- C(td₃ - td₁)/(td₂ - td₃)
- D(td₃ - td₁)/(td₃ - td₂)
18.The general rule for rating refrigeration systems (excepting for CO₂ system) is to approximate following h.p. per ton of refrigeration
- A0.1 to 0.5 h.p. per ton of refrigeration
- B0.5 to 0.8 h.p. per ton of refrigeration
- C1 to 2 h.p. per ton of refrigeration
- D2 to 5 h.p. per ton of refrigeration
19.The freezing point of R-12 is
- A-86.6°C
- B-95.2°C
- C-107.7°C
- D-157.7°C
20.The coefficient of performance (C.O.P.) of a refrigerator working as a heat pump is given by
- A(C.O.P.)P = (C.O.P.)R + 2
- B(C.O.P.)P = (C.O.P.)R + 1
- C(C.O.P)P = (C.O.P)R – 1
- D(C.O.P)P = (C.O.P)R