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ISSN Online: 2377-424X

ISBN Print: 0-85295-345-3

International Heat Transfer Conference 10
August, 14-18, 1994, Brighton, UK

Thermal Contact Conductance of Wavy Metal Surfaces under Arbitrary Ambient Pressure

Get access (open in a dialog) DOI: 10.1615/IHTC10.830
pages 397-402

Аннотация

Thermal contact conductance (TCC) under a wide range of ambient air pressures has been studied with various square test plates made of stainless steel (SUS304), aluminum alloy (A6061) and copper (C1020). The surfaces of the plates were machined in such a way that the contact interface exhibited both microscopic roughness and macroscopic waviness so as to simulate practical heat transfer surfaces. The nominal contact pressure applied to the plates was limited to the low ranges (0.1-0.6 MPa) found in some spacecraft and cryogenic applications. It was demonstrated that the values of the TCC measured in a high vacuum were in good accordance with the authors' prediction technique which does not rely on a heat transfer experiment. Prom the prediction, it was revealed that the thermal constriction resistance due to the surface waviness is predominant in a high vacuum. Variations of the overall TCC measured as a function of ambient air pressure have shown that the heat transfer was. as expected, enhanced with increasing air pressure. A two-stage heat conduction model was proposed to take into account interstitial gas conduction which occurs in the voids between the contacting surfaces. The thermal conductivity of gas was evaluated by the kinetic theory for rarefied gas. It was demonstrated that the present model could explain fairly well the behavior of the overall TCC with respect to ambient pressure, however, some modification is required concerning the characteristic thickness of the gap due to the surface waviness.