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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

Correct Answer :

C. Dry bulb temperature


Related Questions

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The boiling point of ________ is 10.5°C.

A. Ammonia

B. R-12

C. Sulphur dioxide

D. Carbon dioxide

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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

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4

Under cooling in a refrigeration cycle

A. Increases C.O.P

B. Decreases C.O.P

C. C.O.P remains unaltered

D. Other factors decide C.O.P

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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

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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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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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

During humidification process, __________ increases.

A. Wet bulb temperature

B. Relative humidity

C. Dry bulb temperature

D. Specific humidity

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4

In a vapour compression system, the condition of refrigerant before entering the expansion or throttle valve is

A. High pressure saturated liquid

B. Wet vapour

C. Very wet vapour

D. Dry vapour

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Hydrogen is used in Electrolux refrigeration system so as to _________ the rate of evaporation of the liquid ammonia passing through the evaporator.

A. Equalise

B. Reduce

C. Increase

D. None of these

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4

Critical pressure of a liquid is the pressure

A. Above which liquid will remain liquid

B. Above which liquid becomes gas

C. Above which liquid becomes vapour

D. Above which liquid becomes solid

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4

The comfort conditions in air conditioning are at (where DBT = Dry bulb temperature, and RH = Relative humidity)

A. 25°C DBT and 100% RH

B. 20°C DBT and 80% RH

C. 22°C DBT and 60% RH

D. 25°C DBT and 40% RH

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The coefficient of performance is the ratio of the refrigerant effect to the

A. Heat of compression

B. Work done by compressor

C. Enthalpy increase in compressor

D. All of the above

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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

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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During dehumidification process, __________ remains constant.

A. Wet bulb temperature

B. Relative humidity

C. Dry bulb temperature

D. Specific humidity

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The atmospheric air at dry bulb temperature of 15°C enters a heating coil maintained at 40°C. The air leaves the heating coil at 25°C. The bypass factor of the heating coil is

A. 0.376

B. 0.4

C. 0.6

D. 0.67

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4

In a vapour compression refrigeration system, a throttle valve is used in place of an expander because

A. It considerably reduces mass of the system

B. It improves the C.O.P., as the condenser is small

C. The positive work in isentropic expansion of liquid is very small

D. It leads to significant cost reduction

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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

Rating of a domestic refrigerator is of the order of

A. 0.1 ton

B. 5 tons

C. 10 tons

D. 40 tons

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In a vapour compression system, the condition of refrigerant before passing through the condenser is

A. Saturated liquid

B. Wet vapour

C. Dry saturated vapour

D. Superheated vapour

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4

Carbon dioxide is

A. Colourless

B. Odourless

C. Non-flammable

D. All of these

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During cooling and dehumidification, dry bulb temperature

A. Remains constant

B. Increases

C. Decreases

D. None of these

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4

The thermostatic expansion valve operates on the changes in the

A. Degree of superheat at exit from the evaporator

B. Temperature of the evaporator

C. Pressure in the evaporator

D. None of the above

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The vertical and uniformly spaced lines on a psychrometric chart indicates

A. Dry bulb temperature

B. Wet bulb temperature

C. Dew point temperature

D. Specific humidity

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Highest temperature encountered in refrigeration cycle should be

A. Near critical temperature of refrigerant

B. Above critical temperature

C. At critical Temperature

D. Much below critical temperature

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In a domestic vapour compression refrigerator, the refrigerant commonly used is

A. CO₂

B. Ammonia

C. R-12

D. All of these

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One ton of the refrigeration is

A. The standard unit used in refrigeration problems

B. The cooling effect produced by melting 1 ton of ice

C. The refrigeration effect to freeze 1 ton of water at 0°C into ice at 0°C in 24 hours

D. The refrigeration effect to produce 1 ton of ice at NTP conditions

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The evaporator changes the low pressure liquid refrigerant from the expansion valve into

A. High pressure liquid refrigerant

B. Low pressure liquid and vapour refrigerant

C. Low pressure vapour refrigerant

D. None of these

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The coefficient of performance of a domestic refrigerator is ________ as compared to a domestic air-conditioner.

A. Same

B. Less

C. More

D. None of these