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Max. Marks: 100

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G1064 Pages: 3

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
SEVENTH SEMESTER B.TECH DEGREE EXAMINATION(S), MAY 2019

Course Code: ME405
Course Name: REFRIGERATION AND AIR CONDITIONING

Use of Refrigeration tables, Charts and Psychrometric chart is permitted.
PARTA
Answer any three full questions, each carries 10 marks.
Define COP and Tonnes of refrigeration.
In a Bell-Coleman refrigerator air is drawn into the cylinder of the compressor
from cold chamber at a pressure of 1.03 bar and temperature 12°C. After
isentropic compression to 5.5bar the air is cooled at constant pressure to a
temperature of 22°C.The polytropic expansion ‏ء۔۷۱2۹‎ constant follows and air
expanded to 1.03 bar is passed to cold chamber. Determine (1) Work done/kg of
air flow (2) Refrigerating effect/kg of air flow (3) COP
With the help of neat sketches explain working of vortex tube refrigeration
system
A freezer of 20 TR capacity has evaporator and condenser temperature of -30°C
and 25°C respectively. The refrigerant २-12 is sub-cooled by 4 °C before
entering the expansion valve and is superheated by 5°C before entering the
evaporator. If a six cylinder single acting compressor with stroke equal to bore
running at 1000 rpm. is used. Determine 1. COP 2. Theoretical piston
displacement per minute 3. Theoretical bore and stroke
With the help of neat sketches explain the working of a simple vapour
compression refrigeration system.
A food storage locker with R12 refrigerant requires a refrigeration of
2400kJ/min. capacity has an evaporator temperature of 263K and a condenser
temperature of 303K.The refrigerant is sub cooled by 6°C before entering the
expansion valve and vapour is superheated by 7°C before leaving the evaporator
coil. The refrigeration compressor is a two cylinder single acting with stroke
equal to 1.25 times the bore and operates at 1000rpm. Calculate 1. Mass of
refrigerant circulated/min. 2. Heat removed by condenser/min 3.Theoretcal bore

and stroke.

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Duration: 3 Hours

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