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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

Correct Answer :

C. Total heat lines


Related Questions

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4

Which of the following statement is correct?

A. The constant enthalpy lines are also constant wet bulb temperature lines.

B. The wet bulb and dry bulb temperature are equal at saturation condition.

C. The wet bulb temperature is a measure of enthalpy of moist air.

D. All of the above

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4

The capillary tube, as an expansion device, is used in

A. Domestic refrigerators

B. Water coolers

C. Room air conditioners

D. All of these

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4

In order to collect liquid refrigerant and to prevent it from going to a ________, a device known as accumulator is used at the suction of compressor.

A. Compressor

B. Condenser

C. Expansion valve

D. Evaporator

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4

The sensible heat factor during the heating and humidification process is given by (where h₁ = Enthalpy of air entering the heating coil, h₂ = Enthalpy of air leaving the heating coil, and hA = Enthalpy of air at the end of humidification 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 a lithium bromide absorption refrigeration system

A. Lithium bromide is used as a refrigerant and water as an absorbent

B. Water is used as a refrigerant and lithium bromide as an absorbent

C. Ammonia is used as a refrigerant and lithium bromide as an absorbent

D. None of the above

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4

The coefficient of performance of Heat Pump is always __________ one.

A. Equal to

B. Less than

C. Greater than

D. None of these

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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 refrigerant used for absorption refrigerators working on heat from solar collectors is a mixture of water and

A. Carbon dioxide

B. Sulphur dioxide

C. Lithium bromide

D. R-12

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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

In a bootstrap air evaporative cooling system, the evaporator is provided

A. Between the combustion chamber and the first heat exchanger

B. Between the first heat exchanger and the secondary compressor

C. Between the secondary compressor and the second heat exchanger

D. Between the second heat exchanger and the cooling turbine

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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

In a refrigeration system, the expansion device is connected between the

A. Compressor and condenser

B. Condenser and receiver

C. Receiver and evaporator

D. Evaporator and compressor

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4

A heat pump working on a reversed Carnot cycle has a C.O.P. of 5. It works as a refrigerator taking 1 kW of work input. The refrigerating effect will be

A. 1 kW

B. 2 kW

C. 3 kW

D. 4 kW

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4

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

The temperature of ammonia after compression in a vapour compression system is

A. 20 to 50°C

B. 50 to 70°C

C. 70 to 110°C

D. None of these

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4

The evaporator used in household refrigerators is

A. Frosting evaporator

B. Non-frosting evaporator

C. Defrosting evaporator

D. None of these

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4

The C.O.P. of a refrigerator working on a reversed Carnot cycle is (where T₁ = Lowest absolute temperature, and T₂ = Highest absolute temperature)

A. T₁ / (T₂ - T₁)

B. (T₂ - T₁)/T₁

C. (T₁ - T₂)/T₁

D. T₂/ (T₂ - T₁)

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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

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 boiling point of ammonia is

A. 100°C

B. 50°C

C. 33.3°C

D. 0°C

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4

Pick up the correct statement about giving up of heat from one medium to other in ammonia absorption system

A. Strong solution to weak solution

B. Weak solution to strong solution

C. Strong solution to ammonia vapour

D. Ammonia vapours to weak solution

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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

The refrigerant widely used in domestic refrigerators is

A. Ammonia

B. Carbon dioxide

C. Sulphur dioxide

D. R-12

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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 freezing point of R-12 is

A. -86.6°C

B. -95.2°C

C. -107.7°C

D. -135.8°C

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4

The specific humidity during humidification process

A. Remains constant

B. Increases

C. Decreases

D. None of these

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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 lower horizontal line of the refrigeration cycle plotted on pressure-enthalpy diagram represents

A. Condensation of the refrigerant vapour

B. Evaporation of the refrigerant liquid

C. Compression of the refrigerant vapour

D. Metering of the refrigerant liquid

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4

A Bell Coleman refrigerator working on dense air system as compared to open air system, for the same range of temperature, results in ________ power per tonne of refrigeration.

A. Same

B. Lower

C. Higher

D. None of these

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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