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4

A refrigerant compressor is used to

A. Raise the pressure of the refrigerant

B. Raise the temperature of the refrigerant

C. Circulate the refrigerant through the refrigerating system

D. All of the above

Correct Answer :

D. All of the above


Related Questions

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4

In a psychrometric process, the sensible heat added is 30 kJ/s and the latent heat added is 20 kJ/s. The sensible heat factor for the process will be

A. 0.3

B. 0.6

C. 0.67

D. 1.5

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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

When the temperature of the surrounding is higher than the temperature of the body, then the heat loss by convection from the body to the surrounding will be

A. Positive

B. Negative

C. Zero

D. None of these

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4

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, is called

A. Humidity ratio

B. Relative humidity

C. Absolute humidity

D. Degree of saturation

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4

During sensible cooling of air, specific humidity

A. Remains constant

B. Increases

C. Decreases

D. None of these

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4

In case of sensible heating of air, the coil efficiency is given by (where B.P.F. = Bypass factor)

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

Air refrigeration cycle is used in

A. Commercial refrigerators

B. Domestic refrigerators

C. Air-conditioning

D. Gas liquefaction

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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

Freon group of refrigerants are

A. Inflammable

B. Toxic

C. Non-inflammable and toxic

D. Nontoxic and non-inflammable

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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

During humidification process, dry bulb temperature

A. Remains constant

B. Increases

C. Decreases

D. None of these

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4

One ton refrigeration corresponds to

A. 50 kcal/ min

B. 50 kcal/ hr

C. 80 kcal/ min

D. 80 kcal/ hr

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4

The heat rejection factor (HRF) is given by

A. 1 + C.O.P

B. 1 - C.O.P.

C. 1 + (1/C.O.P)

D. 1 - (1/C.O.P)

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4

The difference between dry bulb temperature and dew point temperature, is called

A. Dry bulb depression

B. Wet bulb depression

C. Dew point depression

D. Degree of saturation

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4

Chaperon equation is applicable for registration at

A. Saturation point of vapour

B. Saturation point of liquid

C. Sublimation temperature

D. Triple point

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4

In a saturated air-water vapour mixture, the

A. Dry bulb temperature is higher than wet bulb temperature

B. Dew point temperature is lower than wet bulb temperature

C. Dry bulb, wet bulb and dew point temperature are same

D. Dry bulb temperature is higher than dew point temperature

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4

In vapour compression cycle the condition off refrigerant is dry saturated 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

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

An infinite parallel planes with emissivities e₁ and e₂, the interchange factor for radiation from surface 1 to surface 2 is given by

A. (e₁ + e₂)/ e₁ + e₂ - e₁e₂

B. 1/e₁ + 1/e₂

C. e₁ + e₂

D. e₁e₂

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4

The dehumidification 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

The C.O.P. of a Carnot refrigerator in winter will be _________ as compared to C.O.P. in summer.

A. Same

B. Lower

C. Higher

D. None of these

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4

The refrigerant used in small tonnage commercial machines (hermetically sealed units) is

A. Ammonia

B. Carbon dioxide

C. Sulphur dioxide

D. R-12

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4

Where does the lowest temperature occur in a vapour compression cycle?

A. Condenser

B. Evaporator

C. Compressor

D. Expansion valve

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4

The lowest thermal diffusivity is of

A. Iron

B. Lead

C. Aluminium

D. Rubber

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4

The alignment circle is marked on the psychrometric chart at

A. 20°C DBT and 50% RH

B. 26°C DBT and 50% RH

C. 20°C DBT and 60% RH

D. 26°C DBT and 60% RH

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4

The vapour pressure of refrigerant should be

A. Lower than atmospheric pressure

B. Higher than atmospheric pressure

C. Equal to atmospheric pressure

D. Could be anything

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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

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

R-12 is generally preferred over R-22 in deep freezers since

A. It has low operating pressures

B. It gives higher coefficient of performance

C. It is miscible with oil over large range of temperatures

D. All of the above

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4

During a refrigeration cycle, heat is rejected by the refrigerant in a

A. Compressor

B. Condenser

C. Evaporator

D. Expansion valve