81. Which of the following refrigerant has the lowest freezing point?
R-11
R-12
R-22
Ammonia
✅ The correct answer is option C.
Heat Transfer, Refrigeration and Air Conditioning MCQs
82. One tonne of refrigeration (1TR) means that the heat removing capacity is
21 kJ/min
210 kJ/min
420 kJ/min
620 kJ/min
✅ The correct answer is option B.
83. The ratio of actual heat transfer to the maximum possible heat transfer is known as heat exchanger effectiveness.
Agree
Disagree
✅ The correct answer is option A.
84. When absorptivity (α) = 1, reflectivity (ρ) = 0 and transmittivity (τ) = 0, then the body is said to be a
black body
grey body
opaque body
white body
✅ The correct answer is option A.
85. The by-pass factor of a cooling coil decreases with
decrease in fin spacing and increase in number of rows
increase in fin spacing and increase in number of rows
increase in fin spacing and decrease in number of rows
decrease in fin spacin
✅ The correct answer is option A.
86. In a vapour compression system, the condition of refrigerant before passing through the condenser is
saturated liquid
wet vapour
dry saturated vapour
superheated vapour
✅ The correct answer is option D.
87. The thermal diffusivity for solids is generally less than those for liquids and gases.
TRUE
FALSE
✅ The correct answer is option B.
88. 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
cooled and humidified
cooled and dehumidified
heated and humidified
heated and dehumidifie
✅ The correct answer is option A.
89. Thermal conductivity of air increases with rise in temperature.
Correct
Incorrect
✅ The correct answer is option A.
90. When the temperature of the surrounding is higher than the temperature of the body, then the heat loss by convection from the body to the surrounding will be
positive
negative
zero
none of these
✅ The correct answer is option B.