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4

The ratio of heat extracted in the refrigerator to the work-done on the refrigerant is called

A. Coefficient of performance of refrigeration

B. Coefficient of performance of heat pump

C. Relative coefficient of performance

D. Refrigerating efficiency

Correct Answer :

A. Coefficient of performance of refrigeration


Related Questions

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4

During dehumidification process, __________ remains constant.

A. Wet bulb temperature

B. Relative humidity

C. Dry bulb temperature

D. Specific humidity

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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

In actual air-conditioning applications for R-12 and R-22, and operating at a condenser temperature of 40° C and an evaporator temperature of 5° C, the heat rejection factor is about

A. 1

B. 1.25

C. 2.15

D. 5.12

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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 suction pipe diameter of refrigerating unit compressor in comparison to delivery side is

A. Bigger

B. Smaller

C. Equal

D. Smaller/bigger depending on capacity

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4

The desirable property of a refrigerant is

A. Low boiling point

B. High critical temperature

C. High latent heat of vaporisation

D. All of these

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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

For large tonnage (more than 200 TR) air-conditioning applications, the compressor recommended is

A. Reciprocating

B. Rotating

C. Centrifugal

D. Screw

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4

The wet bulb depression indicates _________ humidity of the air.

A. Absolute

B. Relative

C. Specific

D. None of these

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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

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 wet bulb temperature at 100% relative humidity is ________ dry bulb temperature.

A. Same as

B. Lower than

C. Higher than

D. None 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

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4

Vapour compression refrigeration is somewhat like

A. Carnot cycle

B. Rankines cycle

C. Reversed Carnot cycle

D. None of the above

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4

Highest pressure encountered in a refrigeration system should be

A. Critical pressure of refrigerant

B. Much below critical pressure

C. Much above critical pressure

D. Near critical pressure

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4

In a domestic vapour compression refrigerator, the refrigerant commonly used is

A. CO₂

B. Ammonia

C. R-12

D. All of these

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4

The domestic refrigerator uses following type of compressor

A. Centrifugal

B. Axial

C. Miniature sealed unit

D. Piston type reciprocating

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4

The bypass factor of a cooling coil decreases with

A. Decrease in fin spacing and increase in number of rows

B. Increase in fin spacing and increase in number of rows

C. Increase in fin spacing and decrease in number of rows

D. Decrease in fin spacing and decrease in number of rows

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4

The humidification process, on the psychrometric chart is shown by

A. Horizontal line

B. Vertical line

C. Inclined line

D. Curved line

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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

The freezing point of sulphur dioxide is

A. -56.6°C

B. -75.2°C

C. -77.7°C

D. -135.8°C

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4

In vapour compression cycle, the condition of refrigerant is very wet vapour

A. After passing through the condenser

B. Before passing through the condenser

C. After passing through the expansion or throttle valve

D. Before entering the compressor

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4

For better C.O.P of refrigerator, the pressure range corresponding to temperature in evaporator and condenser must be

A. Small

B. High

C. Equal

D. Anything

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4

Ammonia absorption refrigeration cycle requires

A. Very little work input

B. Maximum work input

C. Nearly same work input as for vapour compression cycle

D. Zero work input

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4

Vertical lines on pressure-enthalpy chart show constant

A. Pressure lines

B. Temperature lines

C. Total heat lines

D. Entropy lines

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4

In case of sensible cooling of air, the coil efficiency is given by

A. B.P.F. - 1

B. 1 - B.P.F.

C. 1/ B.P.F.

D. 1 + B.P.F.

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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

In a vapour absorption refrigeration system, the compressor of the vapour compression system is replaced by

A. Liquid pump

B. Generator

C. Absorber and generator

D. Absorber, generator and liquid pump

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4

In vapour compression cycle the condition of refrigerant is superheated vapour

A. After passing through the condenser

B. Before passing through the condenser

C. After passing through the expansion or throttle valve

D. Before entering the expansion valve

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4

The higher temperature in vapour compression cycle occurs at

A. Receiver

B. Expansion valve

C. Evaporator

D. Compressor discharge