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4

At lower temperatures and pressures, the latent heat of vaporisation of a refrigerant

A. Decreases

B. Increases

C. Remain same

D. Depends on other factors

Correct Answer :

B. Increases


Related Questions

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4

The wet bulb temperature at 100% relative humidity is ________ dry bulb temperature.

A. Same as

B. Lower than

C. Higher than

D. None of these

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4

The thermostatic expansion valve is used in __________ type of evaporators.

A. Flooded

B. DX coil

C. Dry

D. None of these

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4

For proper refrigeration in a cabinet, if the temperature and vapour pressure difference between cabinet and atmosphere is high, then

A. Bigger cabinet should be used

B. Smaller cabinet should be used

C. Perfectly tight vapour seal should be used

D. Refrigerant with lower evaporation temperature should be used

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4

A standard ice point temperature corresponds to the temperature of

A. Water at 0°C

B. Ice at 4°C

C. Solid and dry ice

D. Mixture of ice and water under equilibrium conditions

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4

In Electrolux refrigerator

A. Ammonia is absorbed in hydrogen

B. Ammonia is absorbed in water

C. Ammonia evaporates in hydrogen

D. Hydrogen evaporates in ammonia

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4

A pressure gauge on the discharge side of a refrigerant compressor reads too high. The reasons will be

A. Lack of cooling water

B. Water temperature being high

C. Dirty condenser surface

D. All 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

The material of pipe lines for a system using Freon as a refrigerant should be

A. Brass

B. Copper

C. Steel

D. Aluminium

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4

The refrigerant supplied to a compressor must be

A. Superheated vapour refrigerant

B. Dry saturated liquid refrigerant

C. A mixture of liquid and vapour refrigerant

D. None of these

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4

Which of the following is not a desirable property of a refrigerant?

A. High risibility with oil

B. Low boiling point

C. Good electrical conductor

D. Large latent heat

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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 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

Which of the following statement is correct?

A. The human body can lose heat even if its temperature is less than the atmospheric temperature.

B. The increase in air movement increases the evaporation from the human body.

C. The warm air increases the rate of radiation of heat from the human body.

D. Both (A) and (B)

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4

In a vapour compression system, the condition of refrigerant is dry saturated vapour

A. Before entering the compressor

B. After leaving the compressor

C. Before entering the condenser

D. After leaving the condenser

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4

The condensing pressure due to the presence of non-condensable gases, as compared to that actually required for condensing temperatures without non-condensable gases,

A. Will be higher

B. Will be lower

C. Will remain unaffected

D. May be higher or lower depending upon the nature of noncondensable gases

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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

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

The wet bulb depression is zero when relative humidity is

A. Zero

B. 0.5

C. 0.75

D. 1.0

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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

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

During dehumidification process, the relative humidity

A. Remains constant

B. Increases

C. Decreases

D. None of these

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4

In a domestic refrigerator, a capillary tube controls the flow of refrigerant from the

A. Expansion valve to the evaporator

B. Evaporator to the thermostat

C. Condenser to the expansion valve

D. Condenser to the evaporator

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4

Relative humidity is given by (where pv = Partial pressure of water vapour, pb = Barometric pressure, ps = Pressure of saturated air, pd = Pressure at dry bulb temperature, pw = Saturation pressure corresponding to wet bulb temperature, and μ = Degree of saturation)

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 refrigerant widely used in domestic refrigerators is

A. Ammonia

B. Carbon dioxide

C. Sulphur dioxide

D. R-12

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4

During heating and dehumidification process, dry bulb temperature

A. Remains constant

B. Increases

C. Decreases

D. None of these

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4

The wet bulb temperature during sensible heating of air

A. Remains constant

B. Increases

C. Decreases

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 dry bulb temperature during sensible heating of air

A. Remains constant

B. Increases

C. Decreases

D. None of these

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4

Carbon dioxide is

A. Colourless

B. Odourless

C. Non-flammable

D. All of these

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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