65.

66.

67.

68.

69.

70.

079/21

Consider an ideal vapor compression refrigeration cycle. If the throttling process
is replaced by an isentropic expansion process, keeping all the other processes
unchanged, which one of the following statements is true for the modified cycle ?
A) Coefficient of performance is the same as that of the original cycle

)
)
)
)

[81]

Coefficient of performance is lower than that of the original cycle
Coefficient of performance is higher than that of the original cycle
Refrigerating effect is lower than that of the original cycle

Which one of the following statements is correct for a superheated vapour ?
A) 115 pressure is less than the saturation pressure at a given temperature
B) Its temperature is less than the saturation temperature at a given pressure

©) Its volume is less than the volume of the saturated vapour at a given
temperature

D) Its enthalpy is less than enthalpy of the saturated vapour at a given pressure

Which one of the following is a CFC refrigerant ?
A) R744 B) R290
C) R502 D) R718

Which of the following has consistent effect on improving COP of simple refrigerating
cycle ?

A) Undercooling B) Superheating

C) Both A) and B) D) None of the above

According to Buckingham’s Pi theorem, the number of dimensionless groups to define
a problem equals

A) Total number of variables

B)
C) Difference between total number of variables and fundamental dimensions
D) None of these

Fundamental dimensions

Which is not true about steam jet refrigeration ?
A) It uses water as refrigerant B) It can be used below 0°C
C) Can be used in breweries D) None of the above

-11-