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4

The lowest temperature during the cycle in a vapour compression system occurs after

A. Compression

B. Expansion

C. Condensation

D. Evaporation

Correct Answer :

D. Evaporation


Related Questions

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4

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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4

The bypass factor for a cooling coil

A. Increases with increase in velocity of air passing through it

B. Decreases with increase in velocity of air passing through it

C. Remains unchanged with increase in velocity of air passing through it

D. May increase or decrease with increase in velocity of air passing through it depending upon the condition of air entering

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4

The refrigeration effect in a dry evaporator compared to flooded evaporator in a similar plant is

A. Same

B. More

C. Less

D. More or less depending on ambient conditions

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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

In refrigerators, the temperature difference between the evaporating refrigerant and the medium being cooled should be

A. High, of the order of 25°

B. As low as possible (3 to 11°C)

C. Zero

D. Any value

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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)

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4

Oil separator in a refrigeration cycle is installed

A. Before compressor

B. Between compressor and condenser

C. Between condenser and evaporator

D. Between condenser and expansion valve

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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

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4

During humidification process, dry bulb temperature

A. Remains constant

B. Increases

C. Decreases

D. None of these

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4

Air conditioning means

A. Cooling

B. Heating

C. Dehumidifying

D. All of these

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4

In a psychrometric process, the sensible heat added is 30 kJ/s and the latent heat added is 20 kJ/s. The sensible heat factor for the process will be

A. 0.3

B. 0.6

C. 0.67

D. 1.5

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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

The humidification 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 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

The domestic refrigerator uses following type of compressor

A. Centrifugal

B. Axial

C. Miniature sealed unit

D. Piston type reciprocating

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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 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

The operating pressure for refrigerating units using R-12 as a refrigerant is

A. 2 bar

B. 8 bar

C. 15 bar

D. 30 bar

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4

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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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 human body feels comfortable when the heat stored in the body is

A. Positive

B. Negative

C. Zero

D. None of these

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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

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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4

Superheating 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

The cooling system used for supersonic aircrafts and rockets is

A. Simple air cooling system

B. Bootstrap air cooling system

C. Reduced ambient air cooling system

D. Regenerative air cooling system

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4

Where does the lowest temperature occur in a vapour compression cycle?

A. Condenser

B. Evaporator

C. Compressor

D. Expansion valve

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4

Which of the following statement is wrong?

A. The performance of the vapour compression refrigerator varies considerably with both vaporising and condensing temperatures.

B. In vapour compression cycle, the useful part of the heat transfer is at the condenser.

C. In ammonia-hydrogen (Electrolux) refrigerator, no compressor, pump or fan is required.

D. The effect of under-cooling the liquid refrigerant is to decrease the coefficient of performance.

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4

Which of the following refrigerant is highly toxic and flammable?

A. Ammonia

B. Carbon dioxide

C. Sulphur dioxide

D. R-12

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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

Nusselt number (NN) is given by

A. NN = hl/k

B. NN = μ cp/k

C. NN = ρ V l /μ

D. NN = V²/t.cp