Refrigeration And Air Conditioning Set 4 MCQs

Q1 | A thermometer installed, in a vapour compression ammonia system, after the condenser shows elevated reading than the normal. It shows that

Condenser needs cleaning

Cooling tower or spray pond not handling the load properly

Uneven water distribution over the condensing surfaces

Any of the above

None of the above

Q2 | One a psychrometric chart cooling and humidification process using spray can be shown by

A line parallel to wet bulb temperature lines

A curve

A line parallel to dry bulb temperature lines

A horizontal line

A vertical line

Q3 | In a vapour compression cycle the refrigerant immediately after expansion valve is in

Liquid form

Wet vapour form

Dry vapour form

Dry and saturated vapour form

None of the above

Q4 | If wet bulb temperature is same as dew point, the relative humidity of air will be

0

25

67

100

50

Q5 | A plant has one 300 ton and one 500 ton centrifugal unit. The total flow of brine is 6400 litres per minute. What should be the distribution of brine flow through each unit

3200 litres each

2400 litres through 300 ton plant and 4000 litres through 500 ton plant

4000 litres through 300 ton plant and 2400 litres through 500 ton plant

Same brine should flow through both

None of the above

Q6 | Which of the following refrigerant has the lowest specific volume?

Ammonia

Freon 22

All the refrigerants have identical specific volume

Freon 12

Carbondioxide

Q7 | Which of the following refrigerant compressor is not classified as positive displacement compressor

Reciprocating compressor

Centrifugal compressor

Rotary compressor

Screw compressor

None of the above

Q8 | Class II group of refrigerants absorb sensible heat while giving refrigeration effect. Which of the following is a class II refrigerant

Ammonia

Carbondioxide

Freon 12

Methyl chloride

All of the above

Q9 | The critical pressure of a liquid is the pressure

Below which a liquid will always be in vapour form

Above which a liquid will remain a liquid

Above which a liquid will always turn into a vapour

Above which a liquid will explode

None of the above

Q10 | Frost on cooling coils

Increases heat transfer

Reduces evaporator temperature

Improves COP of the system

Acts as an insulation, increasing power consumption

Reduces power consumption

Q11 | The coefficient of performance of a domestic refrigerator as compared to that of an air conditioner is gererally

Less

Cannot be compared

More

Air conditioner performance depends on whether conditions

Same

Q12 | The leakage in a refrigeration system using freon is detected by

Acetylene torch

Halide torch

Sulphur stricks

Soap and water

Any of the above

Q13 | The critical temperature for Freon 12 is

Above 100?C

Less than - 50?C

Around - 20?C

0?C

Around 50?C

Q14 | In a vapour compression cycle the lowest temperature occurs in

Evaporator

Expansion valve

Condenser

Receiver

Compressor

Q15 | If dry bulb temperature is 25?C and wet bulb temperature is 18?C, then which of the following temperatures could possibly represent dew point?

14?C

25?C

40?C

43?C

18?C

Q16 | The effect of under cooling the refrigerant is to

Reducing the COP of the cycle

Increase the COP of the cycle

Reduce the refrigerating effect

Increase the super heat of vapour

None of the above

Q17 | Clear ice

Is pure ice

Contains dissolved air

Contains dissolved gases

Is produced by blowing air during freezing

None of the above

Q18 | Two thermometers are constructed in the same way except that one has a spherical bulb and the other an elongated cylindrical bulb. Which one will respond quickly to temperature change?

Spherical bulb thermometer

Cylindrical bulb thermometer

Both will respond in identical manner

Cannot be ascertained on the basis of information provided

None of the above

Q19 | A low wet bulb temperature indicates

Very cool air

Very low humidity

Very low atmospheric temperature

(A) and (B) above

(A) and (C) above

Q20 | On a psychrometric chart sensible heating or cooling is represented by

A horizontal line

A vertical line

Inclined line

Curved line

None of the above

Q21 | During sensible heating of air

Dry bulb temperature increases while enthalpy of moist air decreases

10,000 m height above the surface of earth

Both dry bulb temperature as well as enthalpy decrease

Both dry bulb temperature as well as enthalpy increase

Dry bulb temperature decreases while enthalpy of moist air increases

Q22 | Air and other non-condensable gases (foul gases) get into a refrigeration system through

Decomposition of refrigerant in contact with impurities

Breakdown of oil

Under vacuum operation or during maintenance work

Corrosion

Any of the above

Q23 | Refrigerant 717 is

Freon 22

Air

Freon 12

Carbondioxide

Ammonia

Q24 | The relation between vapour pressure to the enthalpy of vaporisation is expressed in

Vander wall's equation

Energy equation

Maxwell's equation

Clausius Clapeyron equation

Lewis equation

Q25 | For a sensible heating the air is passed over a heating coil which may be

Heated by electric resistance

Heated by passing hot water through the coil

Heated by passing steam through the coil

Heated by direct solar radiations

Heated by any of the above methods