Cc G192063 Pages:3

Reg No.:_ Name:
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
SEVENTH SEMESTER B.TECH DEGREE EXAMINATION(R&S), DECEMBER 2019

Course Code: ME405
Course Name: REFRIGERATION AND AIR CONDITIONING

Max. Marks: 100 Duration: 3 Hours
Use of Refrigeration and Air Conditioning data book is permitted
PARTA
Answer any three full questions, each carries 10 marks. Marks

1 a) What you mean by natural refrigeration and artificial refrigeration? Give two (5)
examples each.

b) With the support of schematic flow diagram and T-S diagram, explain the (5)
working of simple bootstrap aircraft refrigeration system

2 9) A refrigeration system produces ice at the rate of 30 kg/ hour at -2 °C from water (5)
at 25 °C. Determine the refrigeration effect and tonnage of the system. Also, find
the COP, if the power input is 1.1 kW.

b) A refrigeration system working on Bell-Coleman cycle operates with a pressure (5)
ratio of 8 and lower pressure of | bar. The cold chamber exit temperature is
9.1°C and expander inlet temperature is 29°C. If the expansion and compression
follow polytropic process with n = 1.35, determine the COP.

3 a) What is the principle of adiabatic demagnetization refrigeration? Describe its (5)
working using a schematic diagram.

b) In an ammonia vapour compression refrigeration system, the pressure in the (5)
evaporator is 2.1 bar and the ammonia at the evaporator entry is 0.19 dry and at
the exit is 0.86 dry. During compression, the work input per kg of refrigerant is
150 kJ. Calculate the COP and theoretical piston displacement of the
compressor, if the mass flow rate of refrigerant is 4.5 kg/min.

4 a) With the support of p-h diagram, explain the influence of superheating of suction (5)
vapour and sub-cooling of condenser outlet on the COP of vapour compression
refrigeration system.

b) Determine the theoretical COP of a vapour compression refrigerator with carbon (5)
dioxide as refrigerant, working between temperature limits of 25°C and -5°C.

The dryness fraction of carbon dioxide at the compressor suction is 0.6.

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