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4

The bypass factor, in case of sensible cooling of air, is given by (where td₁ = Dry bulb temperature of air entering the cooling coil, td₂ = Dry bulb temperature of air leaving the cooling coil, and td₃ = Dry bulb temperature of the cooling coil)

A. (td₁ -td₃)/( td₂ -td₃)

B. (td₂ -td₃)/( td₁ -td₃)

C. (td₃ -td₁)/( td₂ -td₃)

D. (td₃ -td₂)/( td₁ -td₃)

Correct Answer :

B. (td₂ -td₃)/( td₁ -td₃)


Related Questions

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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

The sensible heat factor during cooling and dehumidification process is given by (where h₁ = Enthalpy of air entering the cooling coil, h₂ = Enthalpy of air leaving the cooling coil, and hA = Enthalpy of air at the end of dehumidification process)

A. (hA - h2)/ (h1 - h2)

B. (h2 - hA)/ (h1 - h2)

C. (h1 - h2)/ (hA - h2)

D. (hA - h1)/ (h2 - h1)

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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

Which of the following statement is correct?

A. In vapour absorption refrigerator, the compression of refrigerant is avoided.

B. Sub-cooling can be achieved by circulating more quantity of cooling water through the condenser.

C. In vapour compression refrigeration, the vapour is drawn in the compressor cylinder during its suction stroke and is compressed adiabatically during the compression stroke.

D. All of the above

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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 reciprocating refrigerant compressors are very suitable for

A. Small displacements and low condensing pressures

B. Large displacements and high condensing pressures

C. Small displacements and high condensing pressures

D. Large displacements and low condensing pressures

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4

The refrigerant after condensation process is cooled below the saturation temperature before throttling. Such a process is called

A. Sub-cooling or under-cooling

B. Super-cooling

C. Normal cooling

D. None of these

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4

The dry bulb temperature lines, on the psychrometric chart are

A. Vertical and uniformly spaced

B. Horizontal and uniformly spaced

C. Horizontal and non-uniformly spaced

D. Curved lines

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4

Air refrigerator works on

A. Reversed Carnot cycle

B. Bell Coleman cycle

C. Both (A) and (B)

D. None of these

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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

Domestic refrigerator working on vapour compression cycle uses the following type of expansion device

A. Electrically operated throttling valve

B. Manually operated valve

C. Thermostatic valve

D. Capillary tube

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4

A mixture of dry air and water vapour, when the air has diffused the maximum amount of water vapour into it, is called

A. Dry air

B. Moist air

C. Saturated air

D. Specific humidity

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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 leakage in a refrigeration system using Freon is detected by

A. Halide torch

B. Sulphur sticks

C. Soap and water

D. All of these

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4

In vapour compression cycle, the condition of refrigerant is high pressure saturated liquid

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

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

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 C.O.P. of a heat pump working on a reversed Carnot cycle is

A. T₁/(T₂ - T₁)

B. (T₂ - T₁)/T₁

C. (T₁ - T₂)/T₁

D. T₂/(T₂ - T₁)

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4

The power per tonne of refrigeration is

A. 3.5/C.O.P.

B. C.O.P/3.5

C. 3.5 × C.O.P.

D. None of these

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4

The reduced ambient air cooling system has

A. One cooling turbine and one heat exchanger

B. One cooling turbine and two heat exchangers

C. Two cooling turbines and one heat exchanger

D. Two cooling turbines and two heat exchangers

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4

Reducing suction pressure in refrigeration cycle

A. Lowers evaporation temperature

B. Increases power required per ton of refrigeration

C. Lowers compressor capacity because vapour is lighter

D. All of the above

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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

A refrigerant with the highest critical pressure is

A. R-11

B. R-12

C. R-22

D. Ammonia

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4

Formation of frost on evaporator in refrigerator

A. Results in loss of heat due to poor heat transfer

B. Increases heat transfer rate

C. Is immaterial

D. Can be avoided by proper design

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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

During heating and humidification, the final relative humidity of air

A. Can be lower or higher than that of the entering air

B. Is lower than that of the entering air

C. Is higher than that of the entering air

D. None of the above

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4

In a refrigeration system, heat absorbed in comparison to heat rejected is

A. More

B. Less

C. Same

D. More for small capacity and less for high capacity

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4

The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature, influences the value of C.O.P.

A. More

B. Less

C. Equally

D. Unpredictable

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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

Environmental protection agencies advice against the use of chlorofluorocarbon refrigerants since

A. These react with water vapour and cause acid rain

B. These react with plants and cause greenhouse effect

C. These react with oxygen and cause its depletion

D. These react with ozone layer