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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

Correct Answer :

B. Is more than 1


Related Questions

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4

As relative humidity decreases, the dew point temperature will be ________ wet bulb temperature.

A. Same as

B. Lower than

C. Higher than

D. None of these

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4

In a refrigerating machine, heat rejected is _________ heat absorbed.

A. Equal to

B. Less than

C. Greater than

D. None of these

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4

The fluids used in Electrolux refrigerator are

A. Water and hydrogen

B. Ammonia and hydrogen

C. Ammonia, water and hydrogen

D. None of these

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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

The C.O.P. of an absorption type refrigerator is given by (where T₁ = Temperature at which the working substance receives heat, T₂ = Temperature of cooling water, and T₃ = Evaporator temperature)

A. [T₁ (T₂ - T₃)] / [T₃ (T₁ - T₂)]

B. [T₃ (T₁ - T₂)]/ [T₁ (T₂ - T₃)]

C. [T₁ (T₁ - T₂)] / [T₃ (T₂ - T₃)]

D. [T₃ (T₂ - T₃)] / [T₁ (T₁ - T₂)]

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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

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

The boiling point of carbon dioxide is

A. -20.5°C

B. -50°C

C. -63.3°C

D. -78.3°C

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4

Choose the correct statement

A. A refrigerant should have low latent heat

B. If operating temperature of system is low, then refrigerant with low boiling point should be used

C. Pre-cooling and sub-cooling bf refrigerant are same

D. Superheat and sensible heat of a refrigerant are same

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4

The capillary tube, as an expansion device, is used in

A. Domestic refrigerators

B. Water coolers

C. Room air conditioners

D. All 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

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

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

The human body feels comfortable when the heat stored in the body is

A. Positive

B. Negative

C. Zero

D. None of these

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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

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

Which of the following statement is correct for ammonia as a refrigerant?

A. It is toxic to mucous membranes.

B. It requires large displacement per TR compared to fluoro carbons.

C. It reacts with copper and its alloys.

D. All 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

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 process of under-cooling is generally brought about by

A. Circulating more quantity of cooling water through the condenser

B. Using water colder than the main circulating water

C. Employing a heat exchanger

D. Any one of the above

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4

For ammonia refrigerating systems, the tubes of a shell and tube condenser are made of

A. Copper

B. Aluminium

C. Steel

D. Brass

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4

In a lithium bromide absorption refrigeration system

A. Lithium bromide is used as a refrigerant and water as an absorbent

B. Water is used as a refrigerant and lithium bromide as an absorbent

C. Ammonia is used as a refrigerant and lithium bromide as an absorbent

D. None of the above

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4

A vapour absorption refrigerator uses __________ as a refrigerant.

A. Water

B. Ammonia

C. Freon

D. Aqua-ammonia

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4

The advantage of dry compression is that

A. It permits higher speeds to be used

B. It permits complete evaporation in the evaporator

C. It results in high volumetric and mechanical efficiency

D. All of the above

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4

In aqua ammonia absorption refrigeration system, incomplete rectification leads to accumulation of water in

A. Condenser

B. Evaporator

C. Absorber

D. None of these

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4

The undesirable property of a refrigerant is

A. Non-toxic

B. Non-flammable

C. Non-explosive

D. High boiling point

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4

The minimum temperature to which water can be cooled in a cooling tower is

A. Dew point temperature of air

B. Wet bulb temperature of air

C. Dry bulb temperature of air

D. Ambient air temperature

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4

The specific humidity during humidification process

A. Remains constant

B. Increases

C. Decreases

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

Which of the following statement is wrong?

A. The performance of the vapour compression refrigerator varies considerably with both vaporising and condensing temperatures.

B. In vapour compression cycle, the useful part of the heat transfer is at the condenser.

C. In ammonia-hydrogen (Electrolux) refrigerator, no compressor, pump or fan is required.

D. The effect of under-cooling the liquid refrigerant is to decrease the coefficient of performance.