# Practice Test: Question Set - 06

1. 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

2. The suction pipe diameter of refrigerating unit compressor in comparison to delivery side is
(A) Bigger
(B) Smaller
(C) Equal
(D) Smaller/bigger depending on capacity

3. The coefficient of performance (C.O.P.) of a refrigerator working as a heat pump is given by
(A) (C.O.P.)P = (C.O.P.)R + 2
(B) (C.O.P.)P = (C.O.P.)R + 1
(C) (C.O.P)P = (C.O.P)R - 1
(D) (C.O.P)P = (C.O.P)R

4. Presence of moisture in a refrigerant affects the working of
(A) Compressor
(B) Condenser
(C) Evaporator
(D) Expansion valve

5. During heating and humidification, the final relative humidity of air
(A) Can be lower or higher than that of the entering air
(B) Is lower than that of the entering air
(C) Is higher than that of the entering air
(D) None of the above

6. Which of the following cycles uses air as the refrigerant?
(A) Ericson
(B) Stirling
(C) Carnot
(D) Bell Coleman

7. The curved lines on a psychrometric chart indicates
(A) Dry bulb temperature
(B) Wet bulb temperature
(C) Dew point temperature
(D) Relative humidity

8. On the pressure-enthalpy diagram, condensation and desuperheating is represented by a horizontal line because the process
(A) Involves no change in volume
(B) Takes place at constant temperature
(C) Takes place at constant entropy
(D) Takes place at constant pressure

9. 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
(A) Positive
(B) Negative
(C) Zero
(D) None of these

10. The general rule for rating refrigeration systems (excepting for CO₂ system) is to approximate following h.p. per ton of refrigeration
(A) 0.1 to 0.5 h.p. per ton of refrigeration
(B) 0.5 to 0.8 h.p. per ton of refrigeration
(C) 1 to 2 h.p. per ton of refrigeration
(D) 2 to 5 h.p. per ton of refrigeration

11. The atmospheric air at dry bulb temperature of 15°C enters a heating coil maintained at 40°C. The air leaves the heating coil at 25°C. The bypass factor of the heating coil is
(A) 0.376
(B) 0.4
(C) 0.6
(D) 0.67

12. The change in evaporator temperature in a refrigeration cycle, as compared to change in condenser temperature, influences the value of C.O.P.
(A) More
(B) Less
(C) Equally
(D) Unpredictable

13. Most thermostatic expansion valves are set for a superheat of
(A) 5°C
(B) 10°C
(C) 15°C
(D) 20°C

14. In a refrigeration system, heat absorbed in comparison to heat rejected is
(A) More
(B) Less
(C) Same
(D) More for small capacity and less for high capacity

15. A thermostatic expansion valve in a refrigeration system
(A) Ensures the evaporator completely filled with refrigerant of the load
(B) Is suitable only for constant load systems
(C) Maintains different temperatures in evaporator in proportion to load
(D) None of the above

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