Journal of Xi'an Jiaotong University

Experimental Investigation on Convection Heat Transfer of Supercritical CO₂ in Porous Media
Shi Runfu，Jiang Peixue，Zhang Yu
(Key Laboratory for Thermal Science and Power Engineering of Ministry of Education，Department of Thermal Engineering，Tsinghua University， Beijing 100084，China)

Abstract：Convection heat transfer of CO₂ in a vertical sintered porous tube with particle diameters 0.2-0.28 mm at supercritical pressures was measured experimentally.The effects of heat flux， mass flow rate，inlet pressure，and flow directions on convection heat transfer were investigated. The results show that the strong variations of thermophysical properties significantly affect the convection heat transfer， especially the sharp variation of specific heat at constant pressure near pseudocritical temperature. Convection heat transfer coefficients have a maximum near the pseudocritical temperature with the increase of local fluid temperature.With the increase of heat flux，convection heat transfer coefficients increase to a maximum and then decrease continuously.Convection heat transfer is enhanced with the increase of mass flow rate，but the effect of flow directions on convection heat transfer is not significant. The convection heat transfer coefficients near the pseudocritical temperature increase with the inlet pressure decreasing to the critical pressure due to the increased variations of CO₂ thermophysical properties. However，the effect of pressure on convection heat transfer is small at the fluid temperature far from the pseudocritical temperature.
Keywords：convection heat transfer；supercritical pressure；sintered porous media； experimental investigation