Refrigeration Questions and Answers – Two/Multi Stage Compression with Water Intercooling, Liquid Subcooling and Flash Chamber – 1

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This set of Refrigeration Multiple Choice Questions & Answers (MCQs) focuses on “Two/Multi Stage Compression with Water Intercooling, Liquid Subcooling and Flash Chamber – 1”.

1. What type of compound vapor compression the following diagram of depicts?

a) Two stage vapor compression with liquid intercooler and flash chamber
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, liquid subcooler and flash intercooler

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) and flash chamber is used during processes (7 – 8) and (8 – 9).

2. The heat taken and given by the flash chamber is same.
a) True
b) False

Explanation: The heat taken and given by the flash chamber is same as the flash chamber is an insulated vessel; hence there is no heat exchange between the flash chamber and the atmosphere.

3. Find the coefficient of performance when the refrigeration effect (Re) is 145.7 and the work done (W) is 32.46 KJ.
a) 4.5
b) 5.5
c) 4.6
d) 5.6

Explanation: COP = $$\frac{210×Q}{W}$$
COP = $$\frac{Re}{W} = \frac{145.7}{32.46}$$
= 4.5.

4. By using flash chambers the total work done per kg of refrigerant is reduced.
a) True
b) False

Explanation: By using flash chambers the total work done per kg of refrigerant is reduced as the refrigerant can be expanded close to the liquid line and hence work done per kg reduces.

5. Which one of the following is not an advantage of water intercooling when used in a multi stage compression?
a) Reduces the work to be done in high pressure
b) Reduces the specific volume of the refrigerant
c) Requires a compressor of more stroke volume
d) Requires a compressor of less stroke volume

Explanation: When water intercooling is used in a multi stage compression the work to be done in high pressure is reduced, the specific volume of the refrigerant is reduced and a compressor of less stroke volume is required.

6. What is the value of Refrigeration effect if m2 = 2 kg/min, m3 = 0.8 kg/min and enthalpies for the refrigerant at saturated vapor and saturated liquid line are 1420 and 1260 kJ/kg?
a) 192
b) 194
c) 196
d) 129

Explanation: Given: m2 = 2 kg/min
m3 = 0.8 kg/min
h1 = 1420 kJ/kg and hf10 = h11 = 1260 kJ/kg
As, m1 = m2 – m3
= 2 – 0.8
= 1.2
Refrigeration effect = m1 (h1 – h11)
= 1.2 (1420 – 1260)
= 1.2 x 160
= 192 kJ/min.

Sanfoundry Global Education & Learning Series – Refrigeration & Air Conditioning.