Refrigeration And Air Conditioning Set 1

Mechanical Engineering

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This set of Refrigeration and Air conditioning Multiple Choice Questions & Answers (MCQs) focuses on Refrigeration And Air Conditioning Set 1

Q1 | In which part of the vapour compression cycle there is abrupt change in pressure and temperature
  • Drier
  • Solenoid valve
  • Expansion valve
  • The change is gradual throughout the cycle
  • Evaporator
Answer: Expansion valve
Q2 | The ratio of sensible heat to total heat is known as
  • Relative humidity
  • Humidification ratio
  • Sensible heat factor
  • Specific humidity
  • Dew point
Answer: Sensible heat factor
Q3 | The flow of the refrigerant in a refrigeration cycle is controlled by
  • Copper tubing
  • Compressor
  • Expansion valve
  • Evaporator
  • Condenser
Answer: Expansion valve
Q4 | The refrigerant used for the air-conditioning of passenger aircraft cabin is
  • Air
  • Carbondioxide
  • Freon 11
  • Ammonia
  • Freon 12
Answer: Carbondioxide
Q5 | Under increased atmospheric pressure (as compared to the standard conditions) the steam will condense at
  • 100?C
  • More than 100?C
  • Depends on other conditions
  • Less than 100?C
  • Has nothing to do with pressure
Answer: More than 100?C
Q6 | Which refrigerant has the highest critical point temperature?
  • Ammonia
  • Freon 11
  • Freon 12
  • Freon 22
  • None of the above
Answer: Freon 11
Q7 | The ratio of high temperature to low temperature for reversed Carnot refrigerator is 1.25. The COP will be
  • 2
  • 3
  • 4
  • 5
  • All of the above
Answer: 4
Q8 | When the higher temperature is fixed, the COP of a refrigerating machine can be improved by
  • Operating the machine at higher speeds
  • Operating the machine at lower speeds
  • Raising the higher temperature
  • Lowering the higher temperature
  • None of the above
Answer: Raising the higher temperature
Q9 | A reversed Carnot cycle has a COP of 4. The ratio of higher temperature to lower temperature will be
  • 1.5
  • 2
  • 1.25
  • 2.5
  • None of the above
Answer: 1.25
Q10 | A plate of vane used to direct or control movement of fluid or air within the confined area is known as
  • Baffle
  • Bellows
  • Regulator
  • Diffuser
  • None of the above
Answer: Baffle
Q11 | The leaks of refrigerant from a cycle may be detected by
  • Halide torch test
  • Sulphur candle test
  • Soap and water test
  • Any of above
  • None of the above
Answer: Any of above
Q12 | Super-conductors
  • Cannot be magnetised at low temperatures
  • Can be rubbed with other superconductors without frictional effects at low temperatures
  • Offer no resistance to flow of electricity at low remperatures
  • Offer no resistance to flow of heat at low temperatures
  • Offer no resistance to flow of fluids at low temperatures
Answer: Offer no resistance to flow of electricity at low remperatures
Q13 | A desicant is
  • A process of removing heat under controlled conditions
  • A substance which reduces the viscosity of liquids
  • A solid substance capable of removing moisture from a gas, liquid or solid
  • Anammonia and a water solution
  • Heat given off by cargo
Answer: A solid substance capable of removing moisture from a gas, liquid or solid
Q14 | A device designed to remove moisture from a refrigerant is called
  • Dehumidifier
  • Drier
  • Solenoid
  • Expansion valve
  • Humidstat
Answer: Drier
Q15 | The difference between wet and dry bulb temperatures
  • Increases at atmospheric temperature
  • Increases as air gets wet
  • Increases as air gets drier
  • remains constant always
  • None of the above
Answer: Increases as air gets drier
Q16 | In a vapour compression cycle the vapour as it leaves the compressor is
  • In liquid form
  • Wet vapour
  • Dry vapour
  • Dry and saturated vapour
  • None of the above
Answer: Dry and saturated vapour
Q17 | Refrigerant No. 717 is
  • Ammonia
  • Freon 12
  • Carbondioxide
  • Freon 22
  • Methyl chloride
Answer: Ammonia
Q18 | In a domestic refrigerator if the compressor runs continuously, it shows that
  • The system is working perfectly all right
  • The refrigeration is to full capacity
  • The system is overloaded
  • Any of the above
  • None of the above
Answer: The system is overloaded
Q19 | The ability of an evaporator to absorb heat does not depends on
  • Temperature difference between the evaporator and the surrounding air
  • Its size, surface condition and material
  • Kind of refrigerant used
  • Velocity of turbulence
  • Compressor speed
Answer: Kind of refrigerant used
Q20 | pH value of a brine solution is
  • More than
  • 14
  • 70
  • Less than 7
  • Could be any value
Answer: Could be any value
Q21 | In case of freon as refrigerant the pipe lines should be of
  • Copper
  • Brass
  • Seamless steel tubes
  • Stainless steel tubes
  • None of the above
Answer: Seamless steel tubes
Q22 | When Freon 12 is used as a refrigerant in vapour compression cycle, the mass circulated per ton of refrigerating effect will be nearly
  • 1.8 kg
  • 0.5 kg
  • 12 kg
  • 1 kg
  • 0.2 kg
Answer: 1.8 kg
Q23 | In control cooling water system, chromates, phosphates and silicates are added to water
  • To remove odour
  • To increase remove foreign particle
  • To inhibit corrosion
  • To prevent scale formation
  • To prevent algae growth
Answer: To inhibit corrosion
Q24 | In a psychrometric chart horizontal line indicate
  • Percentage humidity
  • Dew point temperature
  • Wet bulb temperature
  • Relative humidity
  • Dry bulb temperature
Answer: Dew point temperature
Q25 | In a mechanical refrigeration system the highest temperature of refrigerant occurs
  • Between condenser and evaporator
  • In evaporator
  • Before expansion valve
  • Between compressor and condenser
  • Before expansion valve
Answer: Between compressor and condenser
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