Download GTU BE/B.Tech 2019 Summer 8th Sem Old 181901 Refrigeration And Air Conditioning Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER-VIII (OLD) EXAMINATION - SUMMER 2019

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Instructions:

1. Attempt all questions.

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2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

Q.1 (a) Discuss the effect of following on the performance of a vapour compression system 07

1. Effect of suction pressure
2. Effect of delivery pressure

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3. Effect of superheating
4. Effect of sub-cooling of liquid.

(b) An air refrigeration system operating on Bell-Coleman cycle, takes in air from a room at -6°C and compresses it from 1.04 bar to 6.2 bar. The index of compression being 1.26. The compressed air is cooled to 25°C. The ambient temperature is 18°C. Air expands in an expander where index of compression is 1.36. Determine 07

1. C.O.P of the system
2. Quantity of air circulated per minute for production of 1500 kg of ice per day at 0°C from water at 15°C.

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3. Capacity of the plant.

Q.2 (a) Enumerate desirable properties of an ideal refrigerant. 07

(b) Explain Lithium-Bromide vapour absorption system with neat sketch. 07

OR

(b) Explain Boot strap air refrigeration system with neat sketch. 07

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Q.3 (a) State the principle of steam jet refrigeration system. Write at least three advantages and three disadvantages of steam jet refrigeration over other systems 07

(b) Give detailed classification of compressors used in refrigeration and explain any one rotary compressor. 07

OR

Q.3 (a) Enlist various types of expansion valves used in refrigeration and explain any one with neat sketch. 07

(b) Explain compound compression with multiple expansion valves and flash intercooling system. 07

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Q.4 (a) Define following term related to psychrometry 07

1. Saturated air
2. Dry bulb temperature
3. Relative humidity
4. Specific humidity

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5. Dew point temperature
6. Sensible heat factor
7. By-pass factor.

(b) Enumerate and explain the components of cooling load estimate. 07

OR

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Q.4 (a) Discuss the factors affecting human comfort. 07

(b) Atmospheric air at 15°C DBT and 30% RH passes through a furnace and through a humidifier, in such a way that the final DBT is 32 °C and 40% RH. Determine 07

1. Sensible heat factor of the process.

Q.5 (a) Enumerate various methods of air-conditioning duct design and explain in detail the “Equal friction method”. 07

(b) With neat sketch explain working of an Ice Plant. 07

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OR

Q.5 (a) Explain following terms with respect to fan 07

1. Static fan pressure
2. Dynamic fan pressure
3. Specific speed

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4. Static fan efficiency

(b) Classify air conditioning systems. Explain Central air conditioning system with a neat sketch 07