Refrigeration And Air Conditioning MCQ Questions & Answers

71

In vapour compression refrigeration system, refrigerant occurs as liquid between

A) Condenser and expansion valve B) Compressor and evaporator C) Expansion valve and evaporator D) Compressor and condenser

Discuss

Answer & Solution

Answer: Option C

Solution:

In vapour compression refrigeration system, refrigerant occurs as liquid between Expansion valve and evaporator

72

The total pressure exerted by the mixture of air and water vapour is equal to the sum of pressures which each constituent would exert, if it occupied the same space by itself. This statement is called

A) Kinetic theory of gases B) Newton's law of gases C) Dalton's law of partial pressures D) Avogadro's hypothesis

Discuss

Answer & Solution

Answer: Option C

Solution:

Dalton's law also called Dalton's law of partial pressures,
it states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases.

73

Which of the following statement is wrong?

A) The value of C.O.P. is always greater than one B) In a vapour compression system, the condition of refrigerant before entering the compressor is dry saturated vapour C) The space between the saturated liquid line and saturated vapour line, in a pressure enthalpy chart, is wet vapour region D) None of the above

Discuss

Answer & Solution

Answer: Option D

Solution:

-The value of C.O.P. is always greater than one
- In a vapour compression system, the condition of refrigerant before entering the compressor is dry saturated vapour
- The space between the saturated liquid line and saturated vapour line, in a pressure enthalpy chart, is wet

74

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.

Discuss

Answer & Solution

Answer: Option D

Solution:

Subcooling in refrigeration implies cooling the refrigerant in liquid state, at uniform pressure, to a temperature that is less than the saturation temperature, which corresponds to condenser pressure.

75

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

Discuss

Answer & Solution

Answer: Option A

Solution:

one ton of refrigeration is equal to 210 kJ/ min

76

While designing the refrigeration system of an aircraft, the prime consideration is that the

A) System has high C.O.P. B) Power per TR is low C) Mass of refrigerant circulated in the system is low D) Mass of the refrigeration equipment is low

Discuss

Answer & Solution

Answer: Option D

Solution:

While designing the refrigeration system of an aircraft, the prime consideration is that the Mass of the refrigeration equipment is low

77

In aqua ammonia absorption refrigeration system, incomplete rectification leads to accumulation of water in

A) Condenser B) Evaporator C) Absorber D) None of these

Discuss

Answer & Solution

Answer: Option A

Solution:

In aqua ammonia absorption refrigeration system, incomplete rectification leads to accumulation of water in Condenser

78

Air refrigeration operates on

A) Carnot cycle B) Reversed Carnot cycle C) Rankine’s cycle D) Brayton cycle

Discuss

Answer & Solution

Answer: Option D

Solution:

Air refrigeration operates on Brayton cycle

79

The C.O.P. of an absorption type refrigerator is given by (where T₁ = Temperature at which the working substance receives heat, T₂ = Temperature of cooling water and T₃ = Evaporator temperature)

A) $$\frac{{{{\text{T}}_1}\left( {{{\text{T}}_2} - {{\text{T}}_3}} \right)}}{{{{\text{T}}_3}\left( {{{\text{T}}_1} - {{\text{T}}_2}} \right)}}$$ B) $$\frac{{{{\text{T}}_3}\left( {{{\text{T}}_1} - {{\text{T}}_2}} \right)}}{{{{\text{T}}_1}\left( {{{\text{T}}_2} - {{\text{T}}_3}} \right)}}$$ C) $$\frac{{{{\text{T}}_1}\left( {{{\text{T}}_1} - {{\text{T}}_2}} \right)}}{{{{\text{T}}_3}\left( {{{\text{T}}_2} - {{\text{T}}_3}} \right)}}$$ D) $$\frac{{{{\text{T}}_3}\left( {{{\text{T}}_2} - {{\text{T}}_3}} \right)}}{{{{\text{T}}_1}\left( {{{\text{T}}_1} - {{\text{T}}_2}} \right)}}$$

Discuss

Answer & Solution

Answer: Option B

Solution:

The C.O.P. of an absorption type refrigerator is given by $$\frac{{{{\text{T}}_3}\left( {{{\text{T}}_1} - {{\text{T}}_2}} \right)}}{{{{\text{T}}_1}\left( {{{\text{T}}_2} - {{\text{T}}_3}} \right)}}$$
(Where T₁ = Temperature at which the working substance receives heat, T₂ = Temperature of cooling water and T₃ = Evaporator temperature)

80

Critical temperature is the temperature above which

A) A gas will never liquefy B) A gas will immediately liquefy C) Water will evaporate D) Water will never evaporate

Discuss

Answer & Solution

Answer: Option A

Solution:

The critical temperature of a substance is the temperature at and above which vapor of the substance cannot be liquefied, no matter how much pressure is applied

Refrigeration And Air Conditioning MCQ Questions & Answers | Mechanical Engineering