Refrigeration And Air Conditioning MCQ Questions & Answers

61

Which of the following refrigerant has the lowest freezing point?

A) R-11 B) R-12 C) R-22 D) Ammonia

Discuss

Answer & Solution

Answer: Option C

Solution:

R-22 has the lowest freezing point.

62

Which of the following refrigerants has lowest freezing point?

A) Freon-12 B) NH₃ C) CO₂ D) Freon-22

Discuss

Answer & Solution

Answer: Option D

Solution:

Freon-22 has lowest freezing point

63

The colour of the flame of halide torch, in case of leakage of Freon refrigerant, will change to

A) Bright green B) Yellow C) Red D) Orange

Discuss

Answer & Solution

Answer: Option A

Solution:

The colour of the flame of halide torch, in case of leakage of Freon refrigerant, will change to Bright green

64

Short horizontal lines on pressure-enthalpy chart show

A) Constant pressure lines B) Constant temperature lines C) Constant total heat lines D) Constant entropy lines

Discuss

Answer & Solution

Answer: Option A

Solution:

Short horizontal lines on pressure-enthalpy chart shows Constant pressure lines

65

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) $$\frac{{{\text{t}}{{\text{d}}_1} - {\text{t}}{{\text{d}}_3}}}{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}$$ B) $$\frac{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}{{{\text{t}}{{\text{d}}_1} - {\text{t}}{{\text{d}}_3}}}$$ C) $$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_1}}}{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}$$ D) $$\frac{{{\text{t}}{{\text{d}}_3} - {\text{t}}{{\text{d}}_2}}}{{{\text{t}}{{\text{d}}_1} - {\text{t}}{{\text{d}}_3}}}$$

Discuss

Answer & Solution

Answer: Option B

Solution:

The bypass factor, in case of sensible cooling of air, is given by $$\frac{{{\text{t}}{{\text{d}}_2} - {\text{t}}{{\text{d}}_3}}}{{{\text{t}}{{\text{d}}_1} - {\text{t}}{{\text{d}}_3}}}$$
Where,
td₁ = Dry bulb temperature of air entering the cooling coil,
td₂ = Dry bulb temperature of air leaving the cooling coil,
td₃ = Dry bulb temperature of the cooling coil

66

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

Discuss

Answer & Solution

Answer: Option C

Solution:

In air-conditioning of aeroplanes, using air as a refrigerant, the cycle used isReversed Brayton cycle

67

Which of the following refrigerant has the maximum ozone depletion potential in the stratosphere?

A) Ammonia B) Carbon dioxide C) Sulphur dioxide D) Fluorine

Discuss

Answer & Solution

Answer: Option D

Solution:

Fluorine has the maximum ozone depletion potential in the stratosphere

68

Dry bulb temperature is the temperature of air recorded by a thermometer, when

A) It is not affected by the moisture present in the air B) Its bulb is surrounded by a wet cloth exposed to the air C) The moisture present in it begins to condense D) None of the above

Discuss

Answer & Solution

Answer: Option A

Solution:

The Dry Bulb Temperature refers basically to the ambient air temperature. It is called "Dry Bulb" because the air temperature is indicated by a thermometer not affected by the moisture of the air.

69

Wet bulb temperature is the temperature of air recorded by a thermometer, when

A) It is not affected by the moisture present in the air B) Its bulb is surrounded by a wet cloth exposed to the air C) The moisture present in it begins to condense D) None of the above

Discuss

Answer & Solution

Answer: Option B

Solution:

Wet-bulb temperature. The wet-bulb temperature (WBT) is the temperature read by a thermometer covered in water-soaked cloth (wet-bulb thermometer) over which air is passed. At 100% relative humidity, the wet-bulb temperature is equal to the air temperature (dry-bulb temperature) and it is lower at lower humidity.

70

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

Discuss

Answer & Solution

Answer: Option A

Solution:

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

Refrigeration And Air Conditioning MCQ Questions & Answers | Mechanical Engineering