Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 8th Sem Old 181901 Refrigeration And Air Conditioning Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VIII (Old) EXAMINATION ? WINTER 2019
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.
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
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 (ii) mass flow rate
(iii) 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
(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
1. Mass flow rate in different lines
2. Power required
3. COP
07
OR
Q.3 (a) Define following terms:
(i) Saturated air
(ii) Specific humidity
(iii) Relative humidity
(iv) Absolute humidity
(v) Dry bulb temperature
(vi) Dew point temperature
(vii) Wet bulb depression
07
(b) 40 m
3
of air at 35
?
C DBT and 50% R.H. is cooled to 25
?
C DBT maintaining its
specific humidity constant. Determine:
(i) Relative humidity of cooled air;
(ii) 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
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
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Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ?VIII (Old) EXAMINATION ? WINTER 2019
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.
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
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 (ii) mass flow rate
(iii) 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
(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
1. Mass flow rate in different lines
2. Power required
3. COP
07
OR
Q.3 (a) Define following terms:
(i) Saturated air
(ii) Specific humidity
(iii) Relative humidity
(iv) Absolute humidity
(v) Dry bulb temperature
(vi) Dew point temperature
(vii) Wet bulb depression
07
(b) 40 m
3
of air at 35
?
C DBT and 50% R.H. is cooled to 25
?
C DBT maintaining its
specific humidity constant. Determine:
(i) Relative humidity of cooled air;
(ii) 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
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
2
Q.5 (a) Explain Equal friction method of duct designing. Under which situation it is
recommended. Write its limitations.
07
(b) Classify air conditioning systems. Explain Central air conditioning system with a neat
sketch.
07
OR
Q.5 (a) With neat sketch explain working of an Ice Plant. 07
(b) Explain in brief the following :
(1) Filters
(2) Humidifiers used in air conditioning systems
07
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This post was last modified on 20 February 2020