Thursday, October 20, 2016
REFRIGERATION AND AIR CONDITIONING
6th Exam/Mech/5306
Duration: 3 Hrs. Max. Marks: 75
Note: Attempt any five questions. O. No. 1 is compulsory.
Q1 Write short note on any five:
i. Define the following terms:
Refrigerating effect. COP, efficiency
ii. Write any three factors considered for selection of a refrigerant.
iii. Write unites of the following terms: entropy. enthalpy, refrigerating effect, specific humidity, relative humidity mass flow rate
iv. Name any six refrigerants most commonly used.
v. Define DDT, WET and DPT.
vi. Clarify room sensible heat factor, effective room sensible heat factor and grand sensible heat factor.
02 a. Describe briefly the principle and working of a vapour compression system.
b. Give expressions for mass flow rate, entropy, enthalpy. work done, refrigerating effect and GOP.
Q3 a. Give functions and classification of refrigerants.
b. Discuss properties of ‘ideal refrigerants.
Q.4 a. Discuss the working of an air refrigeration system. Give its advantages and disadvantages over vapour compression system.
b. Describe briefly bell Coleman cycle and give expressions for mass flow rate, work done and COP.
Q.5 a. Explain the principle of ammonia absorption system.
b. Describe briefly a solar power refrigeration system. Give its merits and demerits over other systems.
Q.6 a. Explain the functions of an evaporator. Discuss briefly the working of any one evaporator.
Q.7 Explain thermostatic expansion valve and give applications of various expansion valves.
Q.8 Define the following terms and discuss their importance in air conditioning, specific humidity, and relative humidity degree of saturation, sensible heat, latent heat and total enthalpy of air.
Q.9 a. discuss briefly a psychometric chart and give its uses.
b. Describe how heat load in an air conditioning plant is calculated.
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