21. In air-conditioning of airplanes, using air as a refrigerant, the cycle used is –
A. reversed Carnot cycle
B. reversed Brayton cycle
C. reversed Joule cycle
D. reversed Otto cycle
22. The specific humidity during humidification process –
A. remains constant
B. increases
C. decreases
D. None of these
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23. The pressure at the inlet of a refrigerant compressor is called –
A. back pressure
B. Critical Pressure
C. Suction pressure
D. Discharge pressure
24. The lowest temperature during the cycle in a vapor compression system occurs after –
A. Compression
B. Expansion
C. Evaporation
D. Condensation
25. The refrigerant after the condensation process is cooled below the saturation temperature before throttling. Such a process is called –
A. super-cooling
B. normal cooling
C. sub-cooling or under-cooling
D. None of these