1. Choose the correct answer from the given four alternatives.

A condenser of a refrigeration system rejects heat at a rate of 120 kW while the compressor consumes power of 30 kW. The coefficient of performance of the system would be

1/4

4

1/3

3

A refrigerating machine working on reversed Carnot cycle takes out 2 kW of heat from the system while working between the temperature limits of 300 K and 200 K The COP and power consumed are respectively

1 and 1kW

1 and 2kW

2 and 2 kW

2 and 1kW

The refrigerant used for absorption refrigerators working on heat from solar collectors is a mixture of water and

Carbon dioxide

Sulphur dioxide

Lithium bromide

Freon-12

During the adiabatic cooling of moist air

DBT remains constant

Specific humidity remains constant

Relative humidity remains constant

WBT remains constant

A humidification process means

a decrease in relative humidity

an increase in specific humidity

a decrease in temperature

an increase in temperature

Air refrigeration cycle is used in

commercial refrigerators

domestic refrigerators

gas liquefaction

air-conditioning

In a refrigerator plant, if the condenser temperature increases, the power input to the compressor will

decrease

increase

remain the same

be unpredictable

2. Answer any two of the following:

What is refrigeration? How is

ice, and

dry ice used for the purpose of refrigeration

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

A cold storage is to be maintained at while the surroundings are at 35°C. The heat leakage from the surroundings into the cold storage is estimated to be 29 kW. The actual COP of the refrigeration plant used is one-third that of an ideal plant working between the same temperature. Find the power required (in kW) to drive the plant.

3. Answer any two of the following:

Explain in brief vapour absorption refrigeration system with the help of a neat diagram.

What do you understand by saturated air and unsaturated air What is specific humidity When does it became maximum?

Explain why window air-conditioners are preferred in homes and offices.

4. Answer any two of the following:

Determine the ideal COP of a vapour absorption refrigerating system in which the heating, cooling and refrigeration take place at 197°C, 17°C and respectively.

List some applications of refrigeration. What is the need to preserve food What are cold storages? Why are they used?

The capacity of a refrigerator (working on reversed Carnot cycle) is 280 tonnes when operating between -10°C and 25°C.

Determine: CD Quantity of ice produced within 24 hours when water is supplied at 20°C.

Minimum power (in kW) required.

5. Write short notes on any four of the following:

COP of a Refrigerator

Cascade Refrigeration

Expansion Valve

Global Warming

Ton of Refrigeration

Evaporator