A helium filled orifice type pulse tube refrigerator (OPTR) was designed, built and operated to provide cryogenic cooling. The OTPR is a travelling wave thermoacoustic refrigerator that operates on a modified reverse Stirling cycle. The experimental studies are carried out at various values of the mean pressure of helium (0.35 MPa – 2.2 MPa), amplitudes of pressure oscillations, frequencies of operation and sizes of orifice opening. The experimental results are compared with the predictions from a detailed time-dependent numerical model. In the CFD model, the compressible forms of the continuity, momentum and energy equations are solved for both the refrigerant gas (helium) and the porous media regions (the regenerator and the three heat-exchangers) in the OPTR. An improved representation of heat transfer in the porous media is achieved by employing a thermal non-equilibrium model to couple the gas and solid (porous media) energy equations. The model predictions show better comparisons with the experimental results when the effects of wall thicknesses of the various components of the OPTR are included in the model.

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