Refrigeration And Airconditioning - May 2016
Mechanical Engineering (Semester 8)
TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks. 1 (a) Describe a simple vapour compression cycle giving clearly its flow and T-s diagram(7 marks) 1 (b) Give the full name of the following refrigerants:
R-12, R717,R-22,R-134a,R-600,R-150,R-123(7 marks) 2 (a) Sketch bootstrap air cycle refrigeration cycle and derive an expression for its COP.(7 marks)
Solve any one question from Q2(b) & Q2(c)
2 (b) Compare between water cooled and air cooled condensers. Explain evaporative condenser.(7 marks) 2 (c) What are the advantages and disadvantages of steam jet refrigeration system over other type of system? Explain its working principle.(7 marks)
Solve any two question from Q3(a), Q3(b) & Q3(c), Q3(d)
3 (a) (i) Write Short Note: Shell and tube condenser(3 marks) 3 (a) (ii) Write Short Note:Screw compressor(4 marks) 3 (b) With a diagram explain Li-BR Vapor absorption refrigeration system and write its application.(7 marks) 3 (b) The pressure and temperature of mixture of dry air and water vapor are 736mm of Hg and 21 C.The dew point temperature of the mixture is 15 C. Determine the following using steam table:1) Mixture (2) Relative humidity (3) Specific humidity (4) Enthalpy of mixture per Kg of dry air (5) specific volume of mixture per kg of dry air.(7 marks) 3 (c) Explain the following terms:1.Dry bulb temperature 2.specific humidity 3.Relative humidity 4.Thermodynamic wet bulb temperature 5.Dew point temperature 6.Degree of saturation 7.Adiabatic saturation Temperature(7 marks)
Solve any two question from Q4(a), Q4(b) & Q4(c), Q4(d)
4 (a) Explain infiltration of air. What point should be considered while making heat load calculation?(7 marks)
4 (b) An office for seating 30 occupants is to be maintained at 22 C DBT and 55%
RH.The outdoor conditions are 36 C DBT and 27 C WBT.The various loads in the
1)solar heat gain:8500W
2)sensible heat gain per occupants:83 W
3)Latent heat gain peroccupant:100W
4)Lighting load :2500W
5)Sensible heat load from other sources:12000W
Assuming 40% fresh air and 60% of re circulated air passing through the evaporator coil and the bypass factor of 0.12 Determine:1)Dew point temperature of the coil (2)Capacity of the plant(7 marks) 4 (c) Write a brief note on Human comfort and briefly explain factors governing effective temperature(7 marks) 4 (d) What is central air conditioning system? Write advantages and limitations of central air conditioning system.(7 marks)
Solve any two question from Q5(a), Q5(b) & Q5(c), Q5(d)
5 (a) Explain Equal friction method of duct designing. Under which situation it is recommended. Write its limitations.(7 marks) 5 (b) Draw a neat sketch of Automatic Expansion valve and write its advantage and disadvantages.(7 marks) 5 (c) Explain Ice making plant with a suitable diagram.(7 marks) 5 (d) Write classifications of Fans. Explain selection of the Fan using fan characteristic curve.(7 marks)