This set of Refrigeration Multiple Choice Questions & Answers (MCQs) focuses on “Two/Multi Stage Compression with Water Intercooling and Liquid Subcooling – 1”.
1. What type of compound vapor compression is the following diagram of?
a) Two stage vapor compression with liquid intercooler
b) Three stage vapor compression with water intercooler and liquid subcooler
c) Two stage vapor compression with flash intercooler
d) Two stage vapor compression with water intercooler and liquid subcooler
View Answer
Explanation:
The diagram itself shows that it consists of two stage vapor compression with liquid sub cooler as shown in the process (5 – 6) and water intercooler from the process (1 – 2) and (3 – 4). For three stages there would have been three such processes.
2. A compound vapor compression with a liquid subcooler and a liquid intercooler system is used to take 10 TR of refrigeration load (Q). The power required for the refrigerating system P is 557.7 W. What is its COP?
a) 6.87
b) 4.75
c) 3.77
d) 5.86
View Answer
Explanation: COP = \(\frac{210×Q}{W}\)
COP = \(\frac{210×10}{557}\)
= 3.77.
3. The water intercooling reduces the work to be done in low pressure compression.
a) True
b) False
View Answer
Explanation: The water intercooling reduces the work to be done in high pressure compression. It also reduces the specific volume of refrigerant which requires a compressor of small size.
4. The complete desuperheating of the vapor refrigerant is not possible in case of water intercooling.
a) True
b) False
View Answer
Explanation: The complete desuperheating of the vapor refrigerant is not possible in case of water intercooling. It is due to the fact that the temperature of the cooling water used in the water intercooler is not available sufficiently low so as to desuperheat the vapor completely.
5. Which one of the processes is the liquid subcooling process?
a) Process (1 – 2)
b) Process (2 – 3)
c) Process (4 – 5)
d) Process (5 – 6)
View Answer
Explanation: The temperature of saturated liquid refrigerant s further reduced by passing it through a liquid sub cooler as shown in the process (5 – 6).
6. What is the value of the load on the evaporator in terms of TR if the power required to drive the system is 25 kW and C.O.P. is 4?
a) 30.75
b) 28.25
c) 28.15
d) 28.57
View Answer
Explanation: Given: P = 25 kW
C.O.P. = 4
As, Power = Work / 60
Work = Power x 60
= 25 x 60
= 1500 kJ/min
C.O.P. = R.E. / Work
R.E. = C.O.P. x Work
= 4 x 1500
= 6000 kJ/min
R.E. = 210 Q
Q = R.E. / 210
= 6000 / 210
= 28.57 TR.
7. If the compound vapour compression system is working under the load on the evaporator of 15 TR, the enthalpies corresponding to the evaporator are 1400 and 400 kJ/kg respectively. What is the value of the mass flow rate through the evaporator?
a) 3.75
b) 3.25
c) 3.15
d) 3.45
View Answer
Explanation: Given: R.E. = 15 TR = 15 x 210 = 3150 kJ/min
h1 = 1400 kJ/kg and h7 = 400 kJ/kg
As, m = 210 Q / (h1 – h7)
= 3150 / (1400 – 400)
= 3150 / 1000 = 3.15.
Sanfoundry Global Education & Learning Series – Refrigeration & Air Conditioning.
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