MCQ 1 In a refrigerating machine, heat rejected is __________ heat absorbed.

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

MCQ 2 The by-pass factor for a cooling coil

(A) increases with increase in velocity of air passing through it (B) decreases with increase in velocity of air passing through it (C) remains unchanged with increase in velocity of air passing through it (D) may increase or decrease with increase in velocity of air passing through it depending upon the condition of air entering

MCQ 3 In aqua-ammonia and Lithium-bromide water absorption refrigeration systems, the refrigerants are respectively

(A) water and water (B) water and lithium bromide (C) ammonia and lithium bromide (D) ammonia and water

MCQ 4 Thermal diffusivity is a

(A) function of temperature (B) physical property of a substance (C) dimensionless parameter (D) all of these

MCQ 5 The highest thermal diffusivity is of

(A) Iron (B) Lead (C) Concrete (D) Wood

MCQ 6 A perfect black body is one which

(A) is black in colour (B) absorbs heat radiations of all wave lengths falling on it (C) reflects all the heat radiations (D) transmits the heat radiations

MCQ 7 The critical radius is the insulation radius at which the resistance to heat flow is

(A) Maximum (B) Minimum (C) Zero (D) None of these

MCQ 8 The automobile radiator is a heat exchanger of

(A) parallel flow type (B) counter flow type (C) cross flow type (D) regenerator type

MCQ 9 During humidification process, __________ increases.

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

MCQ 10 A vapour absorption refrigerator uses __________ as a refrigerant.

(A) water (B) ammonia (C) freon (D) aqua-ammonia

MCQ 11 The ratio of the thickness of thermal boundary layer to the thickness of hydrodynamic boundary layer is equal to (Prandtl number) n, where n is equal to

(A) −1.3 (B) −2/3 (C) 1 (D) −1

MCQ 12 The process, generally used in winter air-conditioning to warm and humidity the air, is called

(A) humidification (B) dehumidification (C) heating and humidification (D) cooling and dehumidification

MCQ 13 In a heat exchanger with one fluid evaporating or condensing, the surface area required is least in

(A) parallel flow (B) counter flow (C) cross flow (D) all of these

MCQ 14 Which of the following statement is correct?

(A) A grey body is one which absorbs all radiations incident on it. (B) At thermal equilibrium, the emissivity and absorptivity are same. (C) The energy absorbed by a body to the total energy falling on it, is called emissivity. (D) A perfect body is one which is black in colour.

MCQ 15 The conditioned air supplied to the room must have the capacity to take up

(A) room sensible heat load only (B) room latent heat load only (C) both room sensible heat and latent heat loads (D) none of the above

MCQ 16 The evaporator used in house-hold refrigerators is

(A) frosting evaporator (B) non-frosting evaporator (C) defrosting evaporator (D) none of these

MCQ 17 The air cooling system mostly used in transport type aircrafts is

(A) simple air cooling system (B) simple evaporative air cooling system (C) boot-strap air cooling system (D) all of these

MCQ 18 The capacity of the cooling tower and spray ponds __________ as the wet bulb temperature of air decreases.

(A) Increases (B) Decreases (C) Remains constant (D) None of the above

MCQ 19 Air refrigeration cycle is used in

(A) commercial refrigerators (B) domestic refrigerators (C) air-conditioning (D) gas liquefaction

MCQ 20 The capillary tube is not used in large capacity refrigeration systems because

(A) cost is too high (B) capacity control is not possible (C) it is made of copper (D) required pressure drop can not be achieved

MCQ 21 The dry bulb temperature lines, on the psychrometric chart are

(A) vertical and uniformly spaced (B) horizontal and uniformly spaced (C) horizontal and non-uniformly spaced (D) curved lines

MCQ 22 The evaporator used in house-hold refrigerators is

(A) frosting evaporator (B) non-frosting evaporator (C) defrosting evaporator (D) none of these

MCQ 23 The operating temperature of a cold storage is − 2° C. The heat leakage from the surrounding is 30 kW for the ambient temperature of 40° C. The actual C.O.P. of refrigeration plant used is one fourth that of ideal plant working between the same temperatures. The power required to drive the plant is

(A) 1.86 kW (B) 3.72 kW (C) 7.44 kW (D) 18.6 kW

MCQ 24 The refrigerant carbon dioxide is not widely used because of its __________ power require ments per tonne of refrigeration and high operating pressures.

(A) low (B) high (C) medium (D) None of the above

MCQ 25 Upto the critical radius of insulation,

(A) added insulation will increase heat loss (B) added insulation will decrease heat loss (C) convective heat loss will be less than conductive heat loss (D) heat flux will decrease