Explain the term “Ton of refrigeration”.
[3 marks]What is cascade refrigeration system?
[4 marks]How the refrigerants are classified? What are the essentials properties of a good refrigerant?
[7 marks]Give alternate refrigerants for CFC’s and HCFC’s with justification.
[3 marks]Discuss the advantages of the dense air refrigerating system over an open air refrigeration system.
[4 marks]Explain with neat sketch of “simple air cooling system” in aircraft refrigeration and indicate the cycle in T-Sdiagram.
[7 marks]Avapor compressor refrigerator uses methyl chloride (R-40) and operates between temperature limits of -10°Cand 45 °C. At entry to the compressor, the refrigerant is dry saturated and after compression it acquires a temperature of 60°C. Find the COP of the refrigerator. The relevant properties of methyl chloride are as follows. Saturation Enthalpy in kJ/kg Enthalpy in kJ/kg K temp in °C Liquid Vapor Liquid Vapor -10 45.4 460.7 0.183 1.637 40 133.0 483.6 0.485 1.587
[7 marks]Define and write the expression for nozzle efficiency in steam jet refrigeration system.
[3 marks]Compare Vapour absorption system and Vapour compression system.
[4 marks]What are the advantages of compound compression with intercooler over single stage compression?
[7 marks]State the functions of expansion device
[3 marks]Explain with neat sketch “Electrolux Refrigeration system”.
[4 marks]A 10 ton ammonia vapour compression refrigeration system consists of one evaporator and two stage compression. The suction temperature is -30 °Cand condensing temperature of 35 °C. Flash inter-cooling is done between two stages of compression. Find theoretic kW of each compressor and COP of the plant.
[7 marks]What do you mean by Air filter? Explain the various types of Air filter.
[3 marks]Discuss the function of absorber in vapour absorption refrigeration system.
[4 marks]Explain with neat sketch LiBr – H O Absorption refrigeration system2
[7 marks]Define human comfort and explain the factors which affect it.
[3 marks]What is effective temperature? What is its significance in design of air conditioning system.
[4 marks]The amount of air supplied to an air conditioned hall is 300m3/min. The atmospheric conditions are 35°C DBT and 55% RH. The required conditions are 20°C DBT and 60% RH. Find out the sensible heat and latent heat removed from the air per minute. Also find sensible heat factor for the system.1
[7 marks]Discuss effect of wall construction on cooling load.
[3 marks]Describe the different materials used for duct. Classify duct
[4 marks]Aduct of 15m length passes air at the rate of 90m3/min. Assuming the friction factor as 0.005, calculate the pressure drop in the duct in mm of water when (a) the duct is circular of diameter 0.3m; and (b) the duct is of 0.3 m square cross-section.
[7 marks]What different methods are used for determining the duct sizes? Mention the advantages of each.
[3 marks]Define following terms: (1) Specific Humidity (2) Dew point temperature (3) Relative Humidity (4) Degree of saturation
[4 marks]With line diagram explain Central Air-conditioning system of any multi storey building
[7 marks]