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

FirstRanker.com

GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER-VIII (Old) EXAMINATION - WINTER 2019

--- Content provided by⁠ FirstRanker.com ---

Subject Code: 181901 Date: 27/11/2019
Subject Name: Refrigeration And Air-Conditioning
Time: 02:30 PM TO 05:00 PM Total Marks: 70

Instructions:
1. Attempt all questions.

--- Content provided by‌ FirstRanker.com ---

2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Use of refrigerant table/chart and psychrometric chart is permissible.

Q.1 (a) Explain Boot strap air refrigeration system with neat sketch. 07
(b) Discuss the desirable properties of an ideal refrigerant. 07

--- Content provided by⁠ FirstRanker.com ---

Q.2 (a) Explain working of Li-Br vapour absorption refrigeration system with neat sketch. 07
(b) A R-12 vapour compression system has saturated suction temperature of -5°C and
saturated discharge temperature of 40°C, The refrigerant vapour is dry-saturated at
the suction of compressor and becomes superheated after compression. For one
ton of refrigeration capacity, Calculate (i) Refrigerating effect (i1) mass flow rate

--- Content provided by‍ FirstRanker.com ---

(ii1) power and (iv) COP system. 07
OR
(b) Explain steam jet refrigeration system and mention its applications. 07

Q.3 (a) Explain the effect of change of suction pressure and delivery pressure on
performance of vapour compression refrigeration using P-H and T-S diagram. 07

--- Content provided by⁠ FirstRanker.com ---

(b) A Two stage ammonia refrigeration system operates between overall pressure limits
of 15 bar and 2 bar respectively. The liquid is sub-cooled to 30°C. The temperature of
de-superheated vapour leaving the water intercooler is also 30°C. The flash chamber
separates the dry vapour at 5 bar pressure. The liquid refrigerant then expands to 2
bar, the evaporator pressure. The load on the evaporator is 50 kW. Calculate

--- Content provided by‌ FirstRanker.com ---

1. Mass flow rate in different lines
2. Power required
3. COP 07
OR
Q.3 (a) Define following terms:

--- Content provided by⁠ FirstRanker.com ---

(1) Saturated air
(i1) Specific humidity
(111) Relative humidity
(iv) Absolute humidity
(v) Dry bulb temperature

--- Content provided by‌ FirstRanker.com ---

(vi) Dew point temperature
(vii) Wet bulb depression 07
(b) 40 m’ of air at 35°C DBT and 50% R.H. is cooled to 25°C DBT maintaining its
specific humidity constant. Determine:
@1) Relative humidity of cooled air;

--- Content provided by​ FirstRanker.com ---

(i1) Heat removed from air. 07

Q.4 (a) Explain construction, working, advantages and disadvantages of Thermostatic
Expansion valve with neat sketch. 07
(b) Explain the procedure for calculating cooling load due to infiltration air. 07
OR

--- Content provided by​ FirstRanker.com ---

Q.4 (a) Explain flywheel effect as applied to cooling load calculation with neat labeled diagram. 07
(b) Write brief note on Hermetically sealed compressor. 07

Q.5 (a) What are the different types of lubricants used in refrigeration and air conditioning units that are
recommended. Write its limitations. 07
(b) Classify air conditioning systems. Explain Central air conditioning system with a neat

--- Content provided by​ FirstRanker.com ---

sketch. 07
OR
Q.5 (a) With neat sketch explain working of an Ice Plant. 07
(b) Explain in brief the following : 07
(1) Filters

--- Content provided by‍ FirstRanker.com ---

(2) Humidifiers used in air conditioning systems