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This set of Refrigeration and Air conditioning Multiple Choice Questions & Answers (MCQs) focuses on Refrigeration And Air Conditioning Set 9
Q1 | If the suction pressure of a refrigeration compressor is too high, it shows
- Lack of refrigerant on cycle
- Excessive load and evaporator
- Negligible load on evaporator
- Any of above
- None of the above
Q2 | The crankcase explosion of a refrigeration compressor
- Occurs due to ignition of vapours in compressor crank case
- Occurs when load is too high
- Means breakdown in compression
- Occurs between piston and cylinder heads
- Means ignition of refrigeration due to high temperature
Q3 | A cooling tower cools water
- Below wet bulb temperature
- Equal to wet bulb temperature
- Slightly above wet bulb temperature
- Wet bulb has no bearing on cooling load performance
- None of the above
Q4 | While designing air conditioning system for a theatre the various heat loads are categorized as given below. Which one will give lowest heat load?
- Lights
- Neither absorbs nor discards heat
- Outside temperature in summer
- Human beings
- Direct sun
Q5 | The secondary refrigerant used in milk chilling plants is usually
- Brine
- Ammonia solution
- Glycol
- Sodium silicate
- Any of the above
Q6 | Hydrogen cannot be liquefied at room temperature by the application of pressure, because
- It is a diatomic molecule
- It has high viscosity
- Its critical temperature is lower than the normal room temperature
- Its thermal conductivity is high
- It has low density
Q7 | The condension of moisture contained in air will take place at
- Any where between dry bulb temperature and wet bulb temperature
- Dew point temperature
- Dry bulb temperature
- Wet bulb temperature
- Saturation temperature
Q8 | If a discharge pressure of a refrigeration compressor is too high, it shows there is (are)
- Too little or too warm condenser water
- Fouled tubes in shell and tube condenser
- Improper operations of evaporator condenser
- Overcharge of refrigerant
- Any of the above
Q9 | The statement that molecular weight of all gases occupy the same volume at NTP is known as
- First law of thermodynamics
- Joules law
- Charle's law
- Avogadro's law
- Dalton's law
Q10 | The condition of refrigerant before and after the expansion or throttle valve in a vapour compression system is
- Wet vapour, very wet vapour
- Wet vapour, dry vapour
- High pressure saturated liquid, very wet vapour
- Very wet vapour, high pressure, saturated liquid
- None of the above
Q11 | The function of desuperheating coil in a condenser is
- To remove heat from condenser
- To improve performance of a condenser
- To discharge the heat exchanged in condenser to the surroundings
- To remove the heat of superheat of the refrigerant before it enters the condenser
- None of the above
Q12 | When the air temperature reaches the point where relative humidity is 100% the air is saturated because it cannot hold any more moisture. This temperature is called
- Freezing point
- Partial freezing point
- Dew point of air
- Dew point
- Dew point of water vapour
Q13 | An increase in the movement of the molecules within a solid, liquid or gas corresponds to
- A drop in temperature
- No change in temperature
- Latent heat addition/removal
- A rise in temperature
- None of the above
Q14 | Reversed carnot cycle comprises
- two isentropic processes and two adiabatic processes
- two isentropic processes and two isothermal processes
- two isentropic processes and two isobaric processes
- two isentropic processes and two isochoric processes
Q15 | Two Carnot Refrigerators are employed, one for ice making and other for comfort cooling
- The COP of the refrigerator for ice making is higher than that for other
- The COP of the refrigerator for ice making is same as that for the other
- The COP of the refrigerator for ice making is lower than that for other
- The COP of Carnot refrigerator will depend on refrigerant used
Q16 | A reversed Carnot cycle has a COP of 4. The ratio of higher temperature to lower temperature will be
- 1.25
- 1.5
- 2
- 2.5
Q17 | Carnot refrigerator absorbs heat at -13° C and requires 1 kW for each 6.5 kW of heat absorbed, the COP and temperature of heat rejections respectively
- COP = 6.5, t = 27° C
- COP = 7.5, t = 27° C
- COP = 6.5, t = 30° C
- COP = 7.5, t = 37° C
Q18 | The dense air refrigeration system as compared to open air refrigeration system for same range of temperatures using Bell- Colemann cycle requires.
- Same power/Ton of Refrigeration
- Lower power/Ton of Refrigeration
- Higher power/Ton of Refrigeration
- Unpredictable Results.
Q19 | For very high speed planes cruising at Mach number 2.5 and above, the air craft refrigeration system recommended is
- Simple evaporative type
- Boot-strap type
- Regenerative type
- Boot strap evaporative type
Q20 | The air craft system giving Lowest Dry Air Rated Turbine discharge temperature at supersonic cruising speeds of the plane, is
- Reduced ambient system of Refrigeration
- Boot-strap system of Refrigeration
- Regenerative system of Refrigeration
- Boot strap evaporative system of Refrigeration
Q21 | There are two cooling turbines in
- Reduced ambient system of Refrigeration
- Boot-strap system of Refrigeration
- Regenerative system of Refrigeration
- Boot strap evaporative system of Refrigeration
Q22 | There are two stages of compression of air in
- Reduced ambient system of Refrigeration
- Boot-strap system of Refrigeration
- Regenerative system of Refrigeration
- Simple evaporative system of Refrigeration
Q23 | The amount of heat absorbed by the system at low temperature is
- COP
- Refrigerating effect
- work done on the system
- refrigeration efficiency
Q24 | No refrigerator using reversed Carnot cycle has been constructed because
- it is less efficient
- it is uneconomical
- isentropic portions of cycle require low speeds where as isothermal portions require high speeds
- isentropic portions of cycle require high speeds where as isothermal portions require low speeds
Q25 | A refrigeration cycle is usually a
- open cycle
- closed cycle
- mixed cycle
- Hybrid cycle