MCQ 1 The wet bulb temperature during sensible heating of air

(A) remains constant (B) increases (C) decreases (D) None of the above

MCQ 2 The formation of frost on cooling coils in a refrigerator

(A) increases heat transfer (B) improves C.O.P. of the system (C) increases power consumption (D) reduces power consumption

MCQ 3 The heat transfer by conduction through a thick sphere is given by

(A) Q = 2π kr₁r₂ (T₁ − T₂)/(r₂ − r₁) (B) Q = 4π kr₁r₂ (T₁ − T₂)/(r₂ − r₁) (C) Q = 6π kr₁r₂ (T₁ − T₂)/(r₂ − r₁) (D) Q = 8π kr₁r₂ (T₁ − T₂)/(r₂ − r₁)

MCQ 4 The optimum effective temperature for human comfort is

(A) higher in winter than in summer (B) lower in winter than in summer (C) same in winter and summer (D) not dependent on season

MCQ 5 For ammonia refrigerating systems, the tubes of a shell and tube condenser are made of

(A) Copper (B) Aluminium (C) Steel (D) Brass

MCQ 6 The thickness of thermal and hydrodynamic boundary layer is equal if Prandtl number is

(A) equal to one (B) greater than one (C) less than one (D) equal to Nusselt number

MCQ 7 A refrigeration system

(A) Removes heat from a low temperature body and delivers it to a high temperature body (B) Removes heat from a high temperature body and delivers it to a low temperature body (C) Rejects energy to a low temperature body (D) None of the above

MCQ 8 The centrifugal compressors are generally used for refrigerants that require

(A) small displacements and low condensing pressures (B) large displacements and high condensing pressures (C) small displacements and high condensing pressures (D) large displacements and low condensing pressures

MCQ 9 For evaporators and condensers, for the given conditions, the logarithmic mean temperature difference (tm) for parallel flow is __________ that for counter flow.

(A) equal to (B) less than (C) greater than (D) none of the above

MCQ 10 Free convection flow depends on

(A) Density (B) Coefficient of viscosity (C) Gravitational force (D) All of these

MCQ 11 Bell-Coleman cycle is a

(A) reversed Carnot cycle (B) reversed Otto cycle (C) reversed Joule cycle (D) reversed Rankine cycle

MCQ 12 During cooling and dehumidification, dry bulb temperature

(A) remains constant (B) increases (C) decreases (D) None of the above

MCQ 13 For a white body, absorptivity (α) = 0, reflectivity (ρ) = 1 and transmittivity (τ) = 0.

(A) Correct (B) Incorrect (C) Can't say (D) None of the above

MCQ 14 For a given dry bulb temperature, as the relative humidity __________ the wet bulb temperature will increase.

(A) increases (B) decreases (C) can't say (D) none of the above

MCQ 15 In counter-current flow heat exchanger, the logarithmic temperature difference between the fluids is __________ as compared to parallel flow heat exchanger.

(A) same (B) less (C) greater (D) none of the above

MCQ 16 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

MCQ 17 Reynolds number is the ratio of

(A) Energy transferred by convection to that by conduction (B) Kinematic viscosity to thermal diffusivity (C) Inertia force to viscous force (D) None of the above

MCQ 18 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

MCQ 19 If the evaporator temperature is kept constant, the coefficient of performance of a refrigeration cycle __________ with the increase in condenser temperature.

(A) increases (B) decreases (C) can't say (D) none of the above

MCQ 20 A one tonne refrigerating machine means that

(A) One tonne is the total mass of machine (B) One tonne refrigerant is used (C) One tonne of water can be converted into ice (D) One tonne of ice when melts from and at 0° C in 24 hours, the refrigeration effect is equivalent to 210 kJ/min

MCQ 21 Dehydration is the process of removing water vapour from the surrounding air.

(A) True (B) False (C) Can't say (D) None of the above

MCQ 22 A vapour absorption refrigeration system

(A) gives noisy operation (B) gives quiet operation (C) requires little power consumption (D) cools below 0° C

MCQ 23 The heat is transferred by conduction, convection and radiation in

(A) melting of ice (B) boiler furnaces (C) condensation of steam in condenser (D) none of these

MCQ 24 During dehumidification process, __________ remains constant.

(A) wet bulb temperature (B) relative humidity (C) dry bulb temperature (D) specific humidity

MCQ 25 The value of the wave length for maximum emissive power is given by

(A) Kirchhoff's law (B) Stefan's law (C) Wein's law (D) Planck's law