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What is the correct answer?

4

The refrigerant supplied to a compressor must be

A. Superheated vapour refrigerant

B. Dry saturated liquid refrigerant

C. A mixture of liquid and vapour refrigerant

D. None of these

Correct Answer :

A. Superheated vapour refrigerant


Related Questions

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4

For unsaturated air, the dew point temperature is __________ wet bulb temperature.

A. Equal to

B. Less than

C. More than

D. None of these

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4

Aqua ammonia is used as refrigerant in the following type of refrigeration system

A. Compression

B. Direct

C. Indirect

D. Absorption

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4

Pick up the correct statement about giving up of heat from one medium to other in ammonia absorption system

A. Strong solution to weak solution

B. Weak solution to strong solution

C. Strong solution to ammonia vapour

D. Ammonia vapours to weak solution

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4

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

A. Cooled and humidified

B. Cooled and dehumidified

C. Heated and humidified

D. Heated and dehumidified

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4

Critical temperature is the temperature above which

A. A gas will never liquefy

B. A gas will immediately liquefy

C. Water will evaporate

D. Water will never evaporate

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4

The capillary tube is not used in large capacity refrigeration systems because

A. Cost is too high

B. Capacity control is not possible

C. It is made of copper

D. Required pressure drop cannot be achieved

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4

A vapour absorption refrigeration system

A. Gives noisy operation

B. Gives quiet operation

C. Requires little power consumption

D. Cools below 0°C

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4

One ton of refrigeration is equal to the refrigeration effect corresponding to melting of 1000 kg of ice

A. In 1 hour

B. In 1 minute

C. In 24 hours

D. In 12 hours

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4

It is desired to condition the outside air from 70% relative humidity and 45° C dry bulb temperature to 50% relative humidity and 25° C dry bulb temperature (room condition). The practical arrangement will be

A. Dehumidification

B. Cooling and humidification

C. Cooling and dehumidification

D. Dehumidification and pure sensible cooling

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4

In a spray washing system, if the temperature of water is higher than the dry bulb temperature of entering air, then the air is

A. Heated and dehumidified

B. Heated and humidified

C. Cooled and humidified

D. Cooled and dehumidified

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4

The refrigerant after condensation process is cooled below the saturation temperature before throttling. Such a process is called

A. Sub-cooling or under-cooling

B. Super-cooling

C. Normal cooling

D. None of these

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4

One tonne of refrigeration (1TR) means that the heat removing capacity is

A. 21 kJ/min

B. 210 kJ/min

C. 420 kJ/min

D. 620 kJ/min

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4

One of the purposes of sub cooling the liquid refrigerant is to

A. Reduce compressor overheating

B. Reduce compressor discharge temperature

C. Increase cooling effect

D. Ensure that only liquid and not the vapour enters the expansion (throttling) valve

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4

The relative coefficient of performance is

A. Actual COP/theoretical COP

B. Theoretical COP/actual COP

C. Actual COP × theoretical COP

D. None of these

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4

The refrigeration effect in a dry evaporator compared to flooded evaporator in a similar plant is

A. Same

B. More

C. Less

D. More or less depending on ambient conditions

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4

In order to cool and dehumidify a stream of moist air, it must be passed over the coil at a temperature

A. Which lies between the dry bulb and wet bulb temperatures of the incoming stream

B. Which lies between the wet bulb and dew point temperatures of the incoming stream

C. Which is lower than the dew point temperature of the incoming stream

D. Of adiabatic saturation of incoming stream

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4

The general rule for rating refrigeration systems (excepting for CO₂ system) is to approximate following h.p. per ton of refrigeration

A. 0.1 to 0.5 h.p. per ton of refrigeration

B. 0.5 to 0.8 h.p. per ton of refrigeration

C. 1 to 2 h.p. per ton of refrigeration

D. 2 to 5 h.p. per ton of refrigeration

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4

The leaks in a refrigeration system using Freon are detected by

A. Halide torch which on detection produces greenish flame lighting

B. Sulphur sticks which on detection gives white smoke

C. Using reagents

D. Smelling

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4

For air conditioning the operation theatre in a hospital, the percentage of outside air in the air supplied is

A. Zero

B. 20

C. 50

D. 100

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4

The leakage in a refrigeration system using ammonia is detected by

A. Halide torch

B. Sulphur sticks

C. Soap and water

D. All of these

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4

A thermostatic expansion valve in a refrigeration system

A. Ensures the evaporator completely filled with refrigerant of the load

B. Is suitable only for constant load systems

C. Maintains different temperatures in evaporator in proportion to load

D. None of the above

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4

During dehumidification process, the relative humidity

A. Remains constant

B. Increases

C. Decreases

D. None of these

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4

A refrigeration system

A. Removes heat from a low temperature body and delivers it to a high temperature body

B. Removes heat from a high temperature body and delivers it to a low temperature body

C. Rejects energy to a low temperature body

D. None of the above

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4

A valve which maintains a constant degree of superheat at the end of the evaporator coil, is called

A. Automatic expansion valve

B. High side float valve

C. Thermostatic expansion valve

D. Low side float valve

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4

In a vapour compression refrigeration system, a throttle valve is used in place of an expander because

A. It considerably reduces mass of the system

B. It improves the C.O.P., as the condenser is small

C. The positive work in isentropic expansion of liquid is very small

D. It leads to significant cost reduction

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4

The comfort conditions in air conditioning are at (where DBT = Dry bulb temperature, and RH = Relative humidity)

A. 25°C DBT and 100% RH

B. 20°C DBT and 80% RH

C. 22°C DBT and 60% RH

D. 25°C DBT and 40% RH

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4

During humidification process, __________ increases.

A. Wet bulb temperature

B. Relative humidity

C. Dry bulb temperature

D. Specific humidity

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4

Rick up the incorrect statement

A. Lithium bromide used in vapour absorption cycle is non volatile

B. Lithium bromide plant can't operate below 0°C

C. A separator is used in lithium bromide plant to remove the unwanted water vapour by condensing

D. Concentration of solution coming out of lithium bromide generator is more in comparison to that entering the generator

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4

Critical pressure of a liquid is the pressure

A. Above which liquid will remain liquid

B. Above which liquid becomes gas

C. Above which liquid becomes vapour

D. Above which liquid becomes solid

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4

The relative humidity is defined as

A. The mass of water vapour present in 1 m3 of dry air

B. The mass of water vapour present in 1 kg of dry air

C. The ratio of the actual mass of water vapour in a unit mass of dry air to the mass of water vapour in the same mass of dry air when it is saturated at the same temperature and pressure.

D. The ratio of actual mass of water vapour in a given volume of moist air to the mass of water vapour in the same volume of saturated air at the same temperature and pressure