CALCULATED REGENERATOR PERFORMANCE AT 4 K WITH HELIUM-4 AND HELIUM-3

摘要

The helium-4 working fluid in regenerative cryocoolers operating with the cold end near' 4 K deviates considerably from an ideal gas.. As a result, losses in the regenerator, given by the time-averaged enthalpy flux, are increased and are strong functions of the operating pressure and temperature Helium-3, with its lower boiling point, behaves somewhat closer to an ideal gas in this low temperature range and can reduce the losses in 4 K regenerators An analytical model is used to find the fluid properties that strongly influence the regenerator losses as well as the gross refrigeration power The thermodynamic and transport properties of helium-3 were incorporated into the latest NIST regenerator numerical model, known as REGEN.3,3, which was used to model regenerator performance with either helium-4 or helium-3 With this model we show how the use of helium-3 in place of helium-4 can improve the performance of 4 K regenerative cryocoolers The effects of operating pressure, warm-end temperature, and frequency on regenerators with helium-4 and helium-3 are investigated and compared The results are used to find optimum operating conditions. The frequency range investigated varies from 1 Hz to 30 Hz, with particular emphasis on higher frequencies.