Refrigeration And Air Conditioning Set 4

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This set of Refrigeration and Air conditioning Multiple Choice Questions & Answers (MCQs) focuses on Refrigeration And Air Conditioning Set 4

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