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Applications of Refrigeration and Air Conditioning & Refrigerants

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Applications of Refrigeration and Air Conditioning & Refrigerants

  1. 1. Refrigeration and Air Conditioning By N.S. AHER Assistant Professor Department of Mechanical Engineering, Sanjivani College of Engineering, Kopargaon
  2. 2. The Process of achieving and maintaining the temperature below that of the surroundings, the aim being to cool some product or space to required temperature. It refers to the treatment of air so as to simultaneously control its temperature, moisture content , cleanliness, odour and circulation as required by occupant, a process or product in the space. Refrigeration Air conditioning
  3. 3. • Domestic Air Conditioners • Domestic Refrigerator • Automotive Air Conditioners • Evaporative Coolers • Water Coolers • Commercial Refrigeration- Diary, Cold Storage, Ice plant • Commercial Air Conditioning – Multiplex, Hospitals Applications
  4. 4. Room Air Conditioner
  5. 5. Domestic Refrigerator
  6. 6. Evaporative Coolers
  7. 7. Direct Evaporative Cooling Types of Evaporative Cooling Indirect Evaporative Cooling Evaporative Cooling
  8. 8. Direct Evaporative Cooling System
  9. 9. Direct Evaporative Cooling System
  10. 10. • ∈ = (𝑡0− 𝑡 𝑠) 𝑡0− 𝑡0 ,𝑤𝑏𝑡 • Where, • 𝑡0 = Initial Temperature of air • 𝑡 𝑠 = Temperature of supply (product) air • 𝑡0 ,𝑤𝑏𝑡 = Wet bulb temperature of initial atm. air Effectiveness of Direct Evaporative Cooling System
  11. 11. Indirect Evaporative Cooling System
  12. 12. Indirect Evaporative Cooling System
  13. 13. Indirect Evaporative Cooling System
  14. 14. Automotive Air Conditioner System
  15. 15. Automotive Air Conditioner System
  16. 16. Automotive Air Conditioner System
  17. 17. Compressor Heart of the system
  18. 18. Condenser • The Condenser is designed to radiate heat. • Its location is usually in front of the radiator. • As hot compressed gasses are introduced into the top of the Condenser, they’re cooled off. As the gas cools, it condenses and exits the bottom of the Condenser as a high pressure liquid.
  19. 19. Receiver/ Dryer Thermal Expansion Valve
  20. 20. Evaporator
  21. 21. • Located inside the vehicle • Evaporator serves as the heat absorption component • Refrigerant enters the bottom of the Evaporator as a low pressure liquid • The warm air passing through the Evaporator fins causes the refrigerant to boil (refrigerants have very low boiling points). As the refrigerant begins to boil, it can absorb large amounts of heat. Evaporator
  22. 22. Refrigerant • R12 • R 134a
  23. 23. Window air Conditioner
  24. 24. Split air Conditioner
  25. 25. Ice Plant
  26. 26. Refrigerants Primary Refrigerants Secondary Refrigerants
  27. 27. Provide Refrigeration by undergoing phase change process in the evaporator • Used for transporting thermal energy from one location to other • Do not undergo phase change • E.g.: Solutions of water and ethylene glycol, Propylene glycol or calcium chloride Primary Refrigerants Secondary Refrigerants (brines)
  28. 28. Refrigerants Mixtures - Azeotropic - Zeotropic Pure Fluids Natural - Organic (HCs) - Inorganic • NH3 • CO2 • H2O Synthetic - CFCs - HCFCs - HFCs
  29. 29. • Thermodynamic and Thermo-physical properties • Environmental and Safety properties • Economics Refrigerant Selection Criteria
  30. 30. • Suction Pressure: At a given evaporator temperature, Saturation pressure should be above atmospheric for prevention of air or moisture ingress into the system and ease of leak detection. Smaller compressor displacement. • Discharge Pressure: At a given condenser temperature, discharge pressure should be as small as possible to allow light-weight construction of compressor, condenser Thermodynamic and thermo-physical properties
  31. 31. • Pressure Ratio: Should be as small as possible for high volumetric efficiency and low power consumption • Latent heat of vaporization: Should be as large as possible so that required mass flow rate per unit cooling capacity will be small. • Liquid specific heat: Should be small so that degree of subcooling will be large • Vapour specific heat: Should be large so that the degree of superheating will be small Thermodynamic and thermo-physical properties
  32. 32. • Thermal conductivity: Should be high for higher heat transfer coefficients • Viscosity: Should be small for smaller frictional pressure drops Thermodynamic and thermo-physical properties
  33. 33. • Ozone Depletion Potential (ODP): According to Montreal protocol, the ODP of refrigerants should be zero. ODP depends mainly on the presence of chlorine or bromine in the molecules. • R11, R12 – Non zero ODP- Phase out • Global warming potential (GWP):Refrigerant should have as low as GWP. • R134a – Zero ODP but high value of GWP Environmental and safety properties
  34. 34. • Total equivalent warming index (TEWI):TEWI considers both direct (due to release into atmosphere) and indirect (through energy consumption) contributions of refrigerants to global warming. It should be low • Toxicity: Refrigerants used in a refrigeration system should be non toxic. • Flammability Environmental and safety properties

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