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Seventh Semester B.Tech. Degree Examination, June 2009

03-701 : REFRIGERATION AND AIR CONDITIONING (M)

Time : 3 Hours Max. Marks : 100

Insturctions : 1) Use of Psychrometric chart and Refrigeration properties tablepermitted.

2) Answerall questions from PartA andany three questions from

PartB.

PART A

1. What is the difference between a heat pump and a refrigerator ?

2. Explain the concept of magnetic refrigeration.

3. Prove that COP of a Heat Pump = 1 + COP of a refrigerator.

4. What are the advantages of vapour absorption refrigeration system ?

5. Define dew point temperature and wet bulb temperature.

6. Compare vapour compression refrigeration system with air refrigeration system.

7. Discuss on bypass factor, apparatus dew point temperature and RSHF line.

8. Discuss on ozone depletion and green house effect.

9. What is an air washer ?

10. Mention the advantages and disadvantages of split type AC system.

(410=40 Marks)

Reg. No. : .....................................

Name : ..........................................

P.T.O.

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PART B

Module I11. a) Compare reversed Carnots cycle and vapour compression cycle.

b) Explain the working of a Bell-Coleman cycle air refrigeration system. 20

OR12. a) Explain the working of a thermostatic expansion valve.

b) A R22 vapour compression system operating at a condenser temperature of45 C and an evaporator temperature of 10C has a capacity of 20 TR. Determine

i) The mass flow rate of refrigerant,

ii) The COP andiii) The total heat rejected at the condenser. 20

Module II

13. a) Compare vapour compression refrigeration system with vapour absorptionrefrigeration system.

b) Explain the working of an NH3 LiBr vapour absorption refrigeration system. 20

OR

14. a) Compare the properties of various refrigerants used.

b) Explain the working of an ice-plant. 20

Module III

15. a) Discuss on comfort and industrial AC.

b) For an auditorium to be airconditioned, the room design condition is 26C

DBT, 18 C WBT, the outside condition is 40 C DBT, 26 C WBT. The roomsensible and latent heat are 11.1 kW and 3.9 kW respectively. The conditionedair supplied to the room contains 25% fresh air and 75% recirculated room air.

Determine :

i) The amount of fresh air required

ii) The DBT and RH of supply air and

iii) By pass factor, if ADP of cooling coil is 10C. 20

OR16. a) Discuss on summer air conditioning.

b) Air at 20 C DBT and 18 C WBT enters a heating and humidifying apparatus,

from which it leaves at 35C DBT and 30C DPT. Moisture is supplied as liquidwater at 27 C to humidify the air. Find the quantity of heat that must be

added per kg of air through the apparatus. 20