Energy recovery on the expansion process using a turbo expander at a HFC-134a chiller.

Author(s) : CHO C. H., KIM C., CHO S. Y.


An experimental study is conducted on a small turbo expander which can be applied to the expansion process in place of an expansion valve in a regenerator or air-conditioner to recover energy from the throttling process. The operating gas is HFC-134a and the maximum cooling capacity of the air-conditioner used in this experiment is 32.7 kW. Four different axial-type rotors in the turbo expander are tested; two rotors among four are shrouded on the tip of rotor; the first has a mean diameter of 71.85 mm and the second 70.46 mm. These axial-type rotors operate in the supersonic flow generated at the supersonic nozzle, and the partial admission rate is 1.70 or 2.37% depending on the rotor size. In the experiment, pressure and temperature are measured at ten different locations in the experimental apparatus. Performance data of the turbo expander are obtained at many part load operations by adjusting the output power of the generator. Experimental results show that the optimal velocity ratio decreases when the pressure ratio is decreased, and peak efficiencies, which are obtained at locally maximized efficiency depending on the operating condition, vary linearly against the subcooling temperature or the pressure ratio. A maximum 15.8% total-to-static efficiency is obtained when the pressure ratio and the partial admission ratio are 2.66 and 1.7096, respectively. Comparing with the total-to-static efficiencies obtained at a rotor with/without the shroud, the efficiencies obtained with the shroud are improved by nearly 3.7% for all operating conditions.

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  • Original title: Energy recovery on the expansion process using a turbo expander at a HFC-134a chiller.
  • Record ID : 2009-1519
  • Languages: English
  • Source: ACRA-2009. The proceedings of the 4th Asian conference on refrigeration and air conditioning: May 20-22, 2009, Taipei, R.O.C.
  • Publication date: 2009/05/20


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