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Evaluation of total pressure oscillator losses.

Author(s) : BRADLEY P. E., LEWIS M. A., RADEBAUGH R., et al.

Summary

The ratio of piston PV power to the electrical input power typically has been used to define compressor efficiency for regenerative cryocoolers. This definition ignores blowby, irreversible heat transfer, and flow losses within the compressor. A new total loss method redefines compressor efficiency by subtracting the mechanical losses from the PV power at the piston face. The total loss method consists of a set of simple measurements. One measurement accounts for pressure losses within the compressor by measuring the electrical and PV power required for a blanked-off compressor for a given pressure ratio. The second accounts for flow losses by measuring the electrical and PV power for a given stroke with the compressor connected to a large reservoir. The sum of these mechanical losses subtracted from the PV power measured at the piston face gives the estimated PV power delivered to an attached load. In this work the authors evaluate the total loss method for a moderate size pressure oscillator with a swept volume of 4.3 cm. They compare these estimates with system measurements using hot wire anemometry at the compressor outlet to determine the PV power delivered by the compressor to a load and they determine the significance of these losses as they relate to compressor charge pressure and operating frequency. They report on measurements for mean pressures from 1.5 to 2.5 MPa, pressure ratios from 1.0 to 1.3, frequencies of 30, 40, 50, 60, and 70 Hz, and the corresponding mass flows.

Details

  • Original title: Evaluation of total pressure oscillator losses.
  • Record ID : 2008-1071
  • Languages: English
  • Publication date: 2006/06/14
  • Source: Source: Proc. 14th int. Cryocooler Conf., Annapolis, MD
    353-359; fig.; 4 ref.

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