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appreciable pressure drops as the refrigerant flows through the condenser and
evaporator. Ignoring heat transfer between the compressor and its surroundings
and the pressure drops in condensor and evaporator, determine (a) the COP and
(b) the refrigerating capacity in TR.

PART B
Answer any three full questions, each carries 10 marks.

What are the desirable properties of refrigerants? Write a short note on eco-
friendly refrigerants.

Describe the working of a water cooler based on simple vapour compression
refrigeration cycle using a schematic diagram.

What is called 'charging of refrigerant’? Point out minimum two ways to
perform it? Mention minimum two methods for the leak detection of
refrigerants.

How a two stage multi pressure system with flash intercooling is different from
the system with flash gas removal alone. Show the differences using the
schematic and P-h diagrams.

What are the different types of Evaporators used in refrigeration system?
Describe with a neat sketch minimum two types of evaporators commonly
used.

PART C
Answer any four full questions, each carries 10 marks.

Define the psychrometric terms: i) DBT ii) WBT iii) DPT iv) Specific humidity
v) Relative Humidity. Describe and show the following processes on a
representative psychrometric chart: a) Sensible cooling and humidification and
b) Heating and dehumidification and c) sorbent dehumidification.

With the help of schematic diagram describe the working of winter air
conditioning system.

What is the function of thermostat in a refrigeration system? How does it work?
Describe the working of any one type of humidistat widely used in refrigeration
practices.

Air at 32 °C DBT and 70% RH is cooled and dehumidified to the following
conditions: 1) 20 °C and 70% RH, 2) 22 °C and 50% RH and 3) 24 °C and 30%
RH. If the air flow rate of air is 600 litres/sec, find out the heat absorbed in kW

and moisture removed in g/s for the three conditions.

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