No. of Printed Pages: 4 IBIMEE-0321
DIPLOMA -VIEP -MECHANICAL
ENGINEERING (DMEVI)
Term-End Examination
December, 2016

BIMEE-032 REFRIGERATION SYSTEMS
Time 2 hours Maximum Marks: 70

Note: Answer five questions in all. Question no. 1 is compulsory. All questions carry equal marks. Use of scientific calculator is permitted.

1. Choose the correct answer from the given four alternatives:7 x 2=14

In a mechanical refrigeration system, the highest temperature of refrigerant occurs

Between condenser and evaporator

In evaporator

Between compressor and condenser

Before expansion valve

Defrosting of evaporators is done because

Frosting is undesirable

Frosting increases refrigerant effect

Frosting retards heat flow

Frosting obstructs flow of refrigerant

In a refrigeration cycle, the heat is rejected by the refrigerant at

Evaporator

Condenser

Expansion valve

Compressor

The most common type of vapour absorption system in use for industrial application is

Freon 12 and water

Freon 22 and water

Ammonia and water

Hydrogen and water

If the compressor of a refrigeration system is noisy, it shows that

Compressor drive coupling is loose

There is lack of oil

Internal parts of the compressor are broken

Any of the above

The heat removal capacity of a one-ton refrigerator is

400 kJ/min

100 kJ/min

50 kcal/min

50 kJ/min

In a refrigerator, the evaporator is located

On the bottom of the refrigerator

Behind the refrigerator cabinet

Adjacent to the compressor

Inside the refrigerator cabinet

2. Define the COP of a refrigerator. Show that the COP of a heat pump is greater than the COP of a refrigerator by unity.

A refrigeration cycle absorbs heat at and rejects it at 27°C. Calculate its COP. 2x7=14

3. What is refrigeration? How is ice, and

dry ice used for the purpose of refrigeration

Calculate how many kJ/min will the heat pump deliver at 27°C, if it absorbs 1130 kJ/min at -3°C. The COP of the heat pump is 10. 2x7=14

4. What do you understand by dry and wet compression? Which is preferred.and why?

In a cold storage plant, fish is supplied at a temperature of 30°C. The fish is stored in cold storage which is maintained at -8°C. The freezing point offish is -4°C.
If (COP)actual 0.3 of (COP)theoretical,determine the actual COP of the refrigeration plant. 2x7=14

5. What is a multistage vapour compression plant? When is it used?

In an absorption refrigeration system, the saturation temperature of steam at a pressure of 2 bar is 119.62°C. The temperature in the refrigerator is to be maintained at -5°C. The atmospheric temperature is 30°C. Find the maximum COP of the vapour absorption refrigeration system. 2x7=14

6. What are the most widely used refrigerants

A refrigerating machine working on reversed Carnot cycle takes out 2 kW of heat from the system while working between temperature limits of 300 K and 200K Calculate the COP and power consumed by the cycle. 2x7=14

7. What is a vapour absorption refrigeration cycle How does it differ from the vapour compression cycle?

COPref of a reversed Carnot cycle is 5. What is the ratio of the highest absolute temperature to the lowest absolute temperature? 2x7=14