Regenerative and reduced air refrigeration system

Regenerative and reduced air refrigeration system

• 1.
  Regenerative and ReducedAir Refrigeration System PREPARED BY KAUSHAL PATEL
• 2.
  Regenerative Air RefrigerationSystem •The regenerative system is used when the cooling turbine discharge temperature of a simple system is too high. •The diagrammatic layout of generative cooling system is given in figure. It consists of a primary air-to air heat exchanger, a regenerative heat exchanger, and a cooling turbine. Higher pressure, high temperature air coming from compressor is cooled first in the primary heat exchanger, then in regenerative heat exchanger and finally in the cooling turbine. Ram air is used as heat sink in the primary heat exchanger and part of the cold air from the turbine discharge is used as the heat sink in the regenerative heat exchanger. •This system is used for supersonic air-planes.
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  Processes of RegenerativeAir- refrigeration System •Process 1-2: Ramming of air. •Process 2-3: Compression of air in main compressor. •Process 3-4: Cooling of compressed air by ram air in the primary heat exchanger. •Process 4-5: Cooling of air in regenerative heat exchanger. •Process 5-6: Expansion in the cooling turbine. •Process 6-7: Air getting heated to cabin temperature.
• 6.
  Continue… •If Q tonnesof refrigeration is the cooling load in the cabin, the quantity of air required for the refrigeration purpose will be, 𝑚 𝑎 = 3.5 𝑄 𝑐 𝑝(𝑇7−𝑇6) 𝑘𝑔/𝑠 •Let, m1= Total mass of air bled from the main compressor, and m2= Mass of cold air bled from the cooling turbine for regenerative heat exchanger. For the energy balance of regenerative heat exchanger, we have: 𝑚2 𝑐 𝑝 𝑇8 − 𝑇6 = 𝑚1 𝑐 𝑝(𝑇4 − 𝑇5) 𝑚2 = 𝑚1(𝑇8−𝑇6) (𝑇4−𝑇5) where, T8= Temperature of air leaving to atmosphere from the regenerative heat exchanger.
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  Continue… •Power required forrefrigeration system, 𝑃 = 𝑚1 𝑐 𝑝(𝑇3−𝑇2) 3600 𝑘𝑊 •C.O.P of the system, 𝐶. 𝑂. 𝑃 = 3.5𝑄 𝑃
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  Reduced Ambient Air-refrigeration System •Thereduced ambient air-refrigeration system shown in figure includes two cooling turbines and one heat exchanger. •The air reduced for the refrigeration system is bled off from the main compressor. This high pressure high temperature air is cooled initially in the heat exchanger. The air required for cooling is taken from the first cooling turbine (T-1) which lowers the temperature of rammed air which is quite high due to ramming action. •The cooled air from the heat exchanger is passed through the second cooling turbine (T-2) from where the air is supplied to the cabin. •The work of cooling turbines is used to drive the exhaust fan (through reduction gears) which draws the cooling air from the heat exchanger. •This system is used for exceptionally high speed aircraft when the ram air temperature is too high.
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  Processes Of ReducedAmbient Air- refrigeration System •Process 1-2: Ramming of air. •Process 2-3: Compression in the main compressor. •Process 3-4: Cooling of compressed air by ram air which after passing through the first cooling turbine (T-1) is led to the heat exchanger. •Process 4-5: Expansion of air in the second cooling turbine (T-2) up to the cabin pressure. •Process 5-6: Heating of air up to cabin temperature (T6).
• 12.
  Continue… •If Q tonneof refrigeration is the cooling load in the cabin, then the quantity of air required for the refrigeration purpose will be, 𝑚 𝑎 = 3.5 𝑄 𝑐 𝑝(𝑇6−𝑇5) 𝑘𝑔/𝑠 •Power required for the refrigeration system is given by, 𝑃 = 𝑚 𝑎 𝑐 𝑝(𝑇3−𝑇2) 3600 𝑘𝑊 •C.O.P of the system, 𝐶. 𝑂. 𝑃 = 3.5𝑄 𝑃
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  Thank You