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4

The sub-cooling in a refrigeration cycle

A. Does not alter C.O.P.

B. Increases C.O.P.

C. Decreases C.O.P.

D. None of these

Correct Answer :

B. Increases C.O.P.


Related Questions

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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 difference between dry bulb temperature and wet bulb temperature, is called

A. Dry bulb depression

B. Wet bulb depression

C. Dew point depression

D. Degree of saturation

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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

In mechanical refrigeration system, the refrigerant has the maximum temperature

A. In evaporator

B. Before expansion valve

C. Between compressor and condenser

D. Between condenser and evaporator

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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

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 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

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

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

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

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

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

Pressure of water vapour is given by

A. 0.622 Pv/ (Pb - Pv)

B. μ/[1 - (1 - μ) (Ps/Pb)]

C. [Pv (Pb - Pd)]/ [Pd (Pb - Pv)]

D. None of these

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4

The relative coefficient of performance is equal to

A. (Theoretical C.O.P.)/ (Actual C.O.P.)

B. (Actual C.O.P.) /(Theoretical C.O.P.)

C. (Actual C.O.P.) × (Theoretical C.O.P.)

D. None of these

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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

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

In a psychrometric chart, specific humidity (moisture content) lines 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

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

A. Compressor

B. Condenser

C. Evaporator

D. Expansion valve

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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

In order to cool and dehumidify a stream of moist air, it must be passed over the coil at a temperature

A. Which lies between the dry bulb and wet bulb temperatures of the incoming stream

B. Which lies between the wet bulb and dew point temperatures of the incoming stream

C. Which is lower than the dew point temperature of the incoming stream

D. Of adiabatic saturation of incoming stream

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4

Carbon dioxide is

A. Colourless

B. Odourless

C. Non-flammable

D. All of these

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4

In chemical dehumidification process,

A. Dew point temperature decreases

B. Wet bulb temperature decreases

C. Dry bulb temperature increases

D. All of these

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4

The pressure at the outlet of a refrigerant compressor is called

A. Suction pressure

B. Discharge pressure

C. Critical pressure

D. Back pressure

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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

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4

Which of the following cycles uses air as the refrigerant?

A. Ericson

B. Stirling

C. Carnot

D. Bell Coleman

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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

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

In vapour compression cycle using NH₃ as refrigerant, initial charge is filled at

A. Suction of compressor

B. Delivery of compressor

C. High pressure side close to receiver

D. Low pressure side near receiver

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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

In refrigerator, liquid receiver is required between condenser and flow controlling device, if quantity of refrigerant for system is

A. Less than 2 kg

B. More than or equal to 3.65 kg

C. More than 10 kg

D. There is no such consideration