Non-intrusive heat transfer coefficient determination in high porosity reticulated foams

摘要

Non-intrusive measurements of the internal heat transfer coefficients in highly porous metal/ceramic foams were made. Under steady one-dimensional flow conditions, the solid phase is subjected to a step change in heat generation rate via induction heating. By measurement of the gas phase temperature response, an internal heat transfer coefficient based upon the volume-averaged equations for gas and solid phase energy is determined with the help of a computational procedure. An equation set based on volume averaging theory was developed and solved numerically to determine the heat transfer coefficient from the gas phase temperature response. The media is reticulated foam of highly porosity (0.75-0.90) with small gas pathways (25-160 pores per linear inch) and narrow solid ligaments making direct temperature measurement impractical, intrusive and inaccurate. The computational procedure alleviates the need for complicated gas and solid phase temperature measurements and prior knowledge of the heat generation rate is not required. At no point is the fluid/solid porous media interaction disturbed by the presence of temperature sensors and calibration difficulties usually associated with inductively-coupled, sample specific, heat generation systems is avoided.