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Roll No. [ ] HEEEEEEE Total No. of Pages : 02
Total No. of Questions : 09
B.Tech (ME) (Sem.-6)
REFRIGERATION AND AIR CONDITIONING
Subject Code : ME-304
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M.Code : 59057
Time : 3 Hrs. Max. Marks : 60
INSTRUCTIONS TO CANDIDATES :
- SECTION-A is COMPULSORY consisting of TEN questions carrying TWO marks each.
- SECTION-B contains FIVE questions carrying FIVE marks each and students have to attempt any FOUR questions.
- SECTION-C contains THREE questions carrying TEN marks each and students have to attempt any TWO questions.
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SECTION-A
- Write briefly :
- Define ton of refrigeration.
- Define COP.
- Differentiate between open and closed air refrigeration systems.
- Enumerate properties of refrigerants.
- Define secondary refrigerant.
- What are disadvantages of HCFCs?
- Enumerate the principle of vapour absorption refrigeration system.
- Differentiate between DBT and WBT.
- Show the cooling and dehumidification process on psychometric chart.
- Define human comfort.
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SECTION-B
Q2 In a Bell Coleman refrigeration cycle, air is drawn from cold chamber at 1 bar and compressed to 6 bar in the compressor. The compression and expansion indices are 1.25 and 1.30 respectively. Determine the COP and Tonnage of the unit for an air flow rate of 0.5 kg/sec. Neglect the clearance volume and take temperatures at the beginning of compression and expansion to be 7 °C and 37 °C respectively.
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Q3 Explain the desirable properties of common refrigerant used in refrigeration and air conditioning systems.
Q4 Moist air at standard atmospheric pressure is passed over a cooling coil. The inlet state of the air is 30° C DBT, 50% R.H. while the exit state is 15° C DBT and 80% R.H. Show the process on the psychometric chart and determine amount of moisture and heat removed per kg of dry air.
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Q5 With the help of a neat sketch, explain the working of ammonia - water vapour absorption refrigeration systems.
Q6 The following data refer to summer air-conditioning of a building: Outside design conditions: 43° C DBT & 27° C WBT, Inside design conditions: 25° C DBT & 50% R.H, Room sensible heat gain: 84000 kJ/hr, Room latent heat gain: 21000 kJ/hr. Bypass factor of cooling coil used: 0.2, The return air from the room is mixed with the outside air before entry to cooling coil in the ration of 4:1. Determine apparatus dew point of the cooling coil, entry & exit conditions of air for cooling coil, fresh air mass flow rate, and refrigeration load on the cooling coil.
SECTION-C
Q7 a) A Carnot refrigerator requires 1.25 kW/ TR to maintain a region at low temperature of —40 °C. Determine COP, higher temperature of cycle, heat rejected in kJ/min. Also calculate the heat delivered and COP if this device is used as heat pump.
b) A freon —22 refrigeration plant working between the temperature limits of 5 °C & 40 °C produces refrigeration capacity'of 40 TR. What would be its capacity for food freezing for which the evaporator temperature is to be maintained at —35 °C?
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Q8 a) With the help of a neat sketch, explain the construction and working of steam jet refrigeration system.
b) Explain industrial and comfort air conditioning and also distinguish between them.
Q9 a) A three-stage, 10-ton ammonia refrigeration system operates between the overall pressure limits -0f*2 bar and 12 bar with flash inter-cooling. The flash inter-cooling pressures are 4 bar and 8 bar. Find: Refrigerant flow rate through evaporator and the intercoolers; the power required to run the system. Compare the COP of the system with that of simple saturation cycle working between same overall pressure limits.
b) Explain the construction and working of shell and tube evaporator valve giving a neat sketch.
NOTE : Disclosure of Identity by writing Mobile No. or Making of passing request on any page of Answer Sheet will lead to UMC against the Student.
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This download link is referred from the post: PTU B.Tech Question Papers 2020 March (All Branches)
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