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What is the correct answer?

4

Under cooling 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

Correct Answer :

A. Increases C.O.P


Related Questions

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4

The C.O.P. of a refrigeration cycle with lowering of condenser temperature, keeping the evaporator temperature constant, will

A. Increase

B. Decrease

C. May increase or decrease depending on the type of refrigerant used

D. Remain unaffected

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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

Under cooling 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

What is the correct answer?

4

In a vapour compression cycle, the refrigerant immediately after expansion valve is

A. Liquid

B. Sub-cooled liquid

C. Saturated liquid

D. Wet vapour

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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

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

The bank of tubes at the back of domestic refrigerator is

A. Condenser tubes

B. Evaporator tubes

C. Refrigerant cooling tubes

D. Capillary tubes

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4

The evaporator used in household refrigerators is

A. Frosting evaporator

B. Non-frosting evaporator

C. Defrosting evaporator

D. None of these

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4

In order to collect liquid refrigerant and to prevent it from going to a ________, a device known as accumulator is used at the suction of compressor.

A. Compressor

B. Condenser

C. Expansion valve

D. Evaporator

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4

The coefficient of performance (C.O.P.) of a refrigerator working as a heat pump is given by

A. (C.O.P.)P = (C.O.P.)R + 2

B. (C.O.P.)P = (C.O.P.)R + 1

C. (C.O.P)P = (C.O.P)R - 1

D. (C.O.P)P = (C.O.P)R

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4

In vapour compression refrigeration system, refrigerant occurs as liquid between

A. Condenser and expansion valve

B. Compressor and evaporator

C. Expansion valve and evaporator

D. Compressor and condenser

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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

Rating of a domestic refrigerator is of the order of

A. 0.1 ton

B. 5 tons

C. 10 tons

D. 40 tons

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4

The temperature of ammonia after compression in a vapour compression system is

A. 20 to 50°C

B. 50 to 70°C

C. 70 to 110°C

D. None of these

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4

When the lower temperature of a refrigerating machine is fixed, then the coefficient of performance can be improved by

A. Operating the machine at higher speeds

B. Operating the machine at lower speeds

C. Raising the higher temperature

D. Lowering the higher temperature

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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

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4

In S.J. unit, one ton of refrigeration is equal to

A. 210 kJ/ min

B. 21 kJ/ min

C. 420 kJ/ min

D. 840 kJ/ min

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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

The COP of a domestic refrigerator

A. Is less than 1

B. Is more than 1

C. Is equal to 1

D. Depends upon the make

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4

The bypass factor (B. P. F.) in case of sensible heating of air is (Where td₁ = Dry bulb temperature of air entering the heating coil, td₂ = Dry bulb temperature of air leaving the heating coil, and td₃ = Dry bulb temperature of heating coil)

A. (td₂ - td₃)/(td₃ - td₁)

B. (td₃ - td₂)/(td₃ - td₁)

C. (td₃ - td₁)/(td₂ - td₃)

D. (td₃ - td₁)/(td₃ - td₂)

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4

The unit of thermal diffusivity is

A. m/hK

B. m/h

C. m²/h

D. m²/hK

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4

Allowable pressure on high pressure side or ammonia absorption system is of the order of

A. Atmospheric pressure

B. Slightly above atmospheric pressure

C. 24 bars

D. 56 bars

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4

In which of the following refrigeration system, waste heat can be effectively used?

A. Vapour compression cycle

B. Vapour absorption cycle

C. Air refrigeration cycle

D. None of these

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4

Freon group of refrigerants are

A. Inflammable

B. Toxic

C. Non-inflammable and toxic

D. Nontoxic and non-inflammable

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4

A reversible engine has ideal thermal efficiency of 30%. When it is used as a refrigerating machine with all other conditions unchanged, the coefficient of performance will be

A. 1.33

B. 2.33

C. 3.33

D. 4.33

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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 vapour compression system, the condition of refrigerant before passing through the condenser is

A. Saturated liquid

B. Wet vapour

C. Dry saturated vapour

D. Superheated vapour

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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

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

The index which correlates the combined effects of air temperature, relative humidity and air velocity on the human body, is known as

A. Mean radiant temperature

B. Effective temperature

C. Dew point temperature

D. None of these