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What is the correct answer?

4

A condenser of refrigeration system rejects heat at the rate of 120 kW, while its compressor consumes a power of 30 kW. The coefficient of performance of the system will be

A. 1/4

B. 1/3

C. 3

D. 4

Correct Answer :

D. 4


Related Questions

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4

The humidity ratio or specific humidity is the mass of water vapour present in

A. 1 m3 of wet air

B. 1 m3 of dry air

C. 1 kg of wet air

D. 1 kg of dry air

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4

The wet bulb temperature during sensible cooling of air

A. Remains constant

B. Increases

C. Decreases

D. None of these

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4

Degree of saturation or percentage humidity is

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

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4

The lower horizontal line of the refrigeration cycle plotted on pressure-enthalpy diagram represents

A. Condensation of the refrigerant vapour

B. Evaporation of the refrigerant liquid

C. Compression of the refrigerant vapour

D. Metering of the refrigerant liquid

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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

The Freon group of refrigerants are

A. Halocarbon refrigerants

B. Zoetrope refrigerants

C. Inorganic refrigerants

D. Hydrocarbon refrigerants

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4

The optimum effective temperature for human comfort is

A. Higher in winter than in summer

B. Lower in winter than in summer

C. Same in winter and summer

D. Not dependent on season

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4

The process, generally used in summer air conditioning to cool and dehumidify the air, is called

A. Humidification

B. Dehumidification

C. Heating and humidification

D. Cooling and dehumidification

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4

Superheating in a refrigeration cycle

A. Increases C.O.P

B. Decreases C.O.P

C. C.O.P remains unaltered

D. Other factors decide C.O.P

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4

The lowest thermal diffusivity is of

A. Iron

B. Lead

C. Aluminium

D. Rubber

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4

Which of the following refrigerant has the highest freezing point.

A. Ammonia

B. Carbon dioxide

C. Sulphur dioxide

D. R-12

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4

The specific humidity during cooling and dehumidification

A. Remains constant

B. Increases

C. Decreases

D. None of these

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4

Which of the following is not a desirable property of a refrigerant?

A. High risibility with oil

B. Low boiling point

C. Good electrical conductor

D. Large latent heat

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4

In a pressure enthalpy chart, the space to the left of the saturated liquid line represents

A. Wet vapour region

B. Superheated vapour region

C. Sub-cooled liquid region

D. None of these

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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

Air conditioning means

A. Cooling

B. Heating

C. Dehumidifying

D. All of these

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4

A pressure gauge on the discharge side of a refrigerant compressor reads too high. The reasons will be

A. Lack of cooling water

B. Water temperature being high

C. Dirty condenser surface

D. All of these

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4

A condenser of refrigeration system rejects heat at the rate of 120 kW, while its compressor consumes a power of 30 kW. The coefficient of performance of the system will be

A. 1/4

B. 1/3

C. 3

D. 4

What is the correct answer?

4

In chemical dehumidification process,

A. Dew point temperature decreases

B. Wet bulb temperature decreases

C. Dry bulb temperature increases

D. All of these

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4

The condensing pressure due to the presence of non-condensable gases, as compared to that actually required for condensing temperatures without non-condensable gases,

A. Will be higher

B. Will be lower

C. Will remain unaffected

D. May be higher or lower depending upon the nature of noncondensable gases

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4

In aircraft, air refrigeration Cycle is used because of

A. Low weight per tonne of refrigeration

B. High heat transfer rate

C. Low temperature at high altitudes

D. Higher coefficient of performance

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4

For evaporators and condensers, for the given conditions, the logarithmic mean temperature difference (tm) for parallel flow is ________ that for counter flow.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

The wet bulb depression is zero when relative humidity is

A. Zero

B. 0.5

C. 0.75

D. 1.0

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4

In air-conditioning of aeroplanes, using air as a refrigerant, the cycle used is

A. Reversed Carnot cycle

B. Reversed Joule cycle

C. Reversed Brayton cycle

D. Reversed Otto cycle

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4

The thermostatic expansion valve is also called

A. Constant pressure valve

B. Constant temperature valve

C. Constant superheat valve

D. None of these

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4

Dry bulb temperature is the temperature of air recorded by a thermometer, when

A. It is not affected by the moisture present in the air

B. Its bulb is surrounded by a wet cloth exposed to the air

C. The moisture present in it begins to condense

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

Highest temperature encountered in refrigeration cycle should be

A. Near critical temperature of refrigerant

B. Above critical temperature

C. At critical Temperature

D. Much below critical temperature

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4

During sensible cooling of air ________ decreases.

A. Wet bulb temperature

B. Relative humidity

C. Dry bulb temperature

D. Specific humidity

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4

Cooling water is required for following equipment in ammonia absorption plant

A. Condenser

B. Evaporator

C. Absorber

D. Condenser, absorber and separator (rectifier)