91. Emissivity of a body will be equal to its absorptivity at all temperatures.
Yes
No
✅ The correct answer is option B.
Heat Transfer, Refrigeration and Air Conditioning MCQs
92. Which of the following refrigerant has the lowest boiling point?
Ammonia
Carbon dioxide
Sulphur dioxide
R-12
✅ The correct answer is option B.
93. The specific humidity during dehumidification process
remains constant
increases
decreases
✅ The correct answer is option C.
94. When α is absorptivity, ρ is reflectivity and τ is transmittivity, then for a diathermanous body,
α = 1, ρ = 0 and τ = 0
α = 0, ρ = 1 and τ = 0
α = 0, ρ = 0 and τ = 1
α + ρ = 1 and τ = 0
✅ The correct answer is option D.
95. The thermostatic expansion valve is also called
constant pressure valve
constant temperature valve
constant superheat valve
none of these
✅ The correct answer is option C.
96. The freon group of refrigerants are
halo-carbon refrigerants
azeotrope refrigerants
inorganic refrigerants
hydro-carbon refrigera
✅ The correct answer is option A.
97. Reynolds number is the ratio of
energy transferred by convection to that by conduction
kinematic viscosity to thermal diffusivity
inertia force to viscous force
none of the above
✅ The correct answer is option C.
98. The product of Reynolds number and Prandtl number is known as
Stanton number
Biot number
Peclet number
Grashoff number
✅ The correct answer is option C.
99. The refrigerant used for absorption refrigerators working on heat from solar collectors is a mixture of water and
carbon dioxide
sulphur dioxide
lithium bromide
R-12
✅ The correct answer is option C.
100. It is desired to condition the outside air from 70% relative humidity and 45° C dry bulb temperature to 50% relative humidity and 25° C dry bulb temperature (room condition). The practical arrangement will be
dehumidification
cooling and humidification
cooling and dehumidification
dehumidification and p
✅ The correct answer is option C.