260 Important Refrigeration And Air Conditioning MCQ Question and Answer | PDF Free Download
1.In chemical dehumidification process,
- ADew point temperature decreases
- BWet bulb temperature decreases
- CDry bulb temperature increases
- DAll of these
2.The sensible heat factor during cooling and dehumidification process is given by (where h₁ = Enthalpy of air entering the cooling coil, h₂ = Enthalpy of air leaving the cooling coil, and hA = Enthalpy of air at the end of dehumidification process)
- A(hA - h2)/ (h1 - h2)
- B(h2 - hA)/ (h1 - h2)
- C(h1 - h2)/ (hA - h2)
- D(hA - h1)/ (h2 - h1)
3.The sensible heat factor during the heating and humidification process is given by (where h₁ = Enthalpy of air entering the heating coil, h₂ = Enthalpy of air leaving the heating coil, and hA = Enthalpy of air at the end of humidification process)
- A(hA - h2)/ (h1 - h2)
- B(h2 - hA)/ (h1 - h2)
- C(h1 - h2)/ (hA - h2)
- D(hA - h1)/ (h2 - h1)
4.In a vapour absorption refrigeration system, the compressor of the vapour compression system is replaced by
- ALiquid pump
- BGenerator
- CAbsorber and generator
- DAbsorber, generator and liquid pump
5.The comfort conditions in air conditioning are at (where DBT = Dry bulb temperature, and RH = Relative humidity)
- A25°C DBT and 100% RH
- B20°C DBT and 80% RH
- C22°C DBT and 60% RH
- D25°C DBT and 40% RH
6.Environmental protection agencies advice against the use of chlorofluorocarbon refrigerants since
- AThese react with water vapour and cause acid rain
- BThese react with plants and cause greenhouse effect
- CThese react with oxygen and cause its depletion
- DThese react with ozone layer
7.In which of the following refrigeration system, waste heat can be effectively used?
- AVapour compression cycle
- BVapour absorption cycle
- CAir refrigeration cycle
- DNone of these
8.Under cooling in a refrigeration cycle
- AIncreases C.O.P
- BDecreases C.O.P
- CC.O.P remains unaltered
- DOther factors decide C.O.P
9.The superheating in a refrigeration cycle
- ADoes not alter C.O.P.
- BIncreases C.O.P.
- CDecreases C.O.P.
- DNone of these
10.The sub-cooling in a refrigeration cycle
- ADoes not alter C.O.P.
- BIncreases C.O.P.
- CDecreases C.O.P.
- DNone of these
11.Reducing suction pressure in refrigeration cycle
- ALowers evaporation temperature
- BIncreases power required per ton of refrigeration
- CLowers compressor capacity because vapour is lighter
- DAll of the above
12.A certain refrigerating system has a normal operating suction pressure of 10 kg/cm gauge and condensing pressure of about 67 kg/cm. The refrigerant used is
- AAmmonia
- BCarbon dioxide
- CFreon
- DBrine
13.A good refrigerant should have
- AHigh latent heat of vaporisation and low freezing point
- BHigh operating pressures and low freezing point
- CHigh specific volume and high latent heat of vaporization
- DLow C.O.P. and low freezing point
14.R-12 is generally preferred over R-22 in deep freezers since
- AIt has low operating pressures
- BIt gives higher coefficient of performance
- CIt is miscible with oil over large range of temperatures
- DAll of the above
15.For ammonia refrigerating systems, the tubes of a shell and tube condenser are made of
- ACopper
- BAluminium
- CSteel
- DBrass
16.The process, generally used in summer air conditioning to cool and dehumidify the air, is called
- AHumidification
- BDehumidification
- CHeating and humidification
- DCooling and dehumidification
17.The process, generally used in winter air-conditioning to warm and humidity the air, is called
- AHumidification
- BDehumidification
- CHeating and humidification
- DCooling and dehumidification
18.The dehumidification process, on the psychrometric chart, is shown by
- AHorizontal line
- BVertical line
- CInclined line
- DCurved line
19.Hydrogen is used in Electrolux refrigeration system so as to _________ the rate of evaporation of the liquid ammonia passing through the evaporator.
- AEqualize
- BReduce
- CIncrease
- DNone of these
20.Superheating in a refrigeration cycle
- AIncreases C.O.P
- BDecreases C.O.P
- CC.O.P remains unaltered
- DOther factors decide C.O.P