Heat Transfer Refrigeration and Air Conditioning MCQ with Answers

211) When absorptivity (?) = 1, reflectivity (?) = 0 and transmittivity (?) = 0, then the body is said to be a

Answer is:

black body

212) Prandtl number (P_N) is given by P_N = ?.c_p/k.

Answer is:

Yes

213) In a vapour compression system, the condition of refrigerant before passing through the condenser is

Answer is:

superheated vapour

214) A composite slab has two layers of different materials with thermal conductivities k₁ and k₂. If each layer has the same thickness, then the equivalent thermal conductivity of the slab will be

Answer is:

(2k1xk2)/(k1+k2)

215) The critical temperature is the temperature

Answer is:

above which a gas will never liquified

Explanation:

Gases can be converted to liquids by compressing the gas at a suitable temperature.
Gases become more difficult to liquefy as the temperature increases because the kinetic energies of the particles that make up the gas also increase.
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.

211) When absorptivity (?) = 1, reflectivity (?) = 0 and transmittivity (?) = 0, then the body is said to be a

black body

212) Prandtl number (PN) is given by PN = ?.cp/k.

Yes

213) In a vapour compression system, the condition of refrigerant before passing through the condenser is

superheated vapour

214) A composite slab has two layers of different materials with thermal conductivities k1 and k2. If each layer has the same thickness, then the equivalent thermal conductivity of the slab will be

(2k1xk2)/(k1+k2)

215) The critical temperature is the temperature

above which a gas will never liquified

212) Prandtl number (P_N) is given by P_N = ?.c_p/k.

214) A composite slab has two layers of different materials with thermal conductivities k₁ and k₂. If each layer has the same thickness, then the equivalent thermal conductivity of the slab will be