260 Important Refrigeration And Air Conditioning MCQ Question and Answer | PDF Free Download
1.An important characteristic of absorption system of refrigeration is
- Anoisy operation
- Bquiet operation
- Ccooling below 0°C
- Dvery little power consumption
2.The evaporator used in household refrigerators is
- AFrosting evaporator
- BNon-frosting evaporator
- CDefrosting evaporator
- DNone of these
3.Chaperon equation is a relation between
- ATemperature, pressure and enthalpy
- BSpecific volume and enthalpy
- CTemperature and enthalpy
- DTemperature, pressure, specific volume and enthalpy
4.If the evaporator temperature of a plant is lowered, keeping the condenser temperature constant, the h.p. of compressor required will be
- ASame
- BMore
- CLess
- DMore/less depending on rating
5.In vapour compression cycle, the condition of refrigerant is saturated liquid
- AAfter passing through the condenser
- BBefore passing through the condenser
- CAfter passing through the expansion throttle valve
- DBefore entering the expansion valve
6.An infinite parallel planes with emissivities e₁ and e₂, the interchange factor for radiation from surface 1 to surface 2 is given by
- A(e₁ + e₂)/ e₁ + e₂ - e₁e₂
- B1/e₁ + 1/e₂
- Ce₁ + e₂
- De₁e₂
7.A one tonne refrigerating machine means that
- AOne tonne is the total mass of machine
- BOne tonne refrigerant is used
- COne tonne of water can be converted into ice
- DOne tonne of ice when melts from and at 0° C in 24 hours, the refrigeration effect is equivalent to 210 kJ/min
8.When the air is passed through an insulated chamber having sprays of water maintained at a temperature higher than the dew point temperature of entering air but lower than its dry bulb temperature, then the air is said to be
- ACooled and humidified
- BCooled and dehumidified
- CHeated and humidified
- DHeated and dehumidified
9.The unit of thermal diffusivity is
- Am/hK
- Bm/h
- Cm²/h
- Dm²/hK
10.Ammonia is
- ANon-toxic
- BNon-inflammable
- CToxic and non-inflammable
- DHighly toxic and inflammable
11.In vapour compression cycle, the condition of refrigerant is high pressure saturated liquid
- AAfter passing through the condenser
- BBefore passing through the condenser
- CAfter passing through the expansion or throttle valve
- DBefore entering the expansion valve
12.In a vapour compression system, the condition of refrigerant is dry saturated vapour
- ABefore entering the compressor
- BAfter leaving the compressor
- CBefore entering the condenser
- DAfter leaving the condenser
13.In vapour compression cycle the condition off refrigerant is dry saturated vapour
- AAfter passing through the condenser
- BBefore passing through the condenser
- CAfter passing through the expansion or throttle valve
- DBefore entering the compressor
14.The refrigerant used in small tonnage commercial machines (hermetically sealed units) is
- AAmmonia
- BCarbon dioxide
- CSulphur dioxide
- DR-12
15.The refrigeration effect in a dry evaporator compared to flooded evaporator in a similar plant is
- ASame
- BMore
- CLess
- DMore or less depending on ambient conditions
16.When the lower temperature of a refrigerating machine is fixed, then the coefficient of performance can be improved by
- AOperating the machine at higher speeds
- BOperating the machine at lower speeds
- CRaising the higher temperature
- DLowering the higher temperature
17.The evaporator changes the low pressure liquid refrigerant from the expansion valve into
- AHigh pressure liquid refrigerant
- BLow pressure liquid and vapour refrigerant
- CLow pressure vapour refrigerant
- DNone of these
18.The coefficient of performance is the ratio of the refrigerant effect to the
- AHeat of compression
- BWork done by compressor
- CEnthalpy increase in compressor
- DAll of the above
19.In refrigerator, liquid receiver is required between condenser and flow controlling device, if quantity of refrigerant for system is
- ALess than 2 kg
- BMore than or equal to 3.65 kg
- CMore than 10 kg
- DThere is no such consideration
20.Pressure of water vapour is given by
- A0.622 Pv/ (Pb - Pv)
- Bμ/[1 - (1 - μ) (Ps/Pb)]
- C[Pv (Pb - Pd)]/ [Pd (Pb - Pv)]
- DNone of these