Experimental analysis of heat transfer of supercritical fluids in plate heat exchangers

Heat transfer of a supercritical refrigerant with highly variable properties close to pseudo-critical temperature was experimentally investigated in plate heat exchangers. Two different plate corrugation angles (30° and 60°) were examined while the Reynolds and the Prandtl number range from 800 to 4200 and 3.2 to 4.2, respectively. The results are found to be different from those obtained using classical Dittus-Boelter type correlations. Two possible effects were investigated: effect of wall-to-bulk property ratio and that of buoyancy. The former was found to be important and was accounted for in the correlation using the correction factor proposed by Jackson and Hall. The latter was found not to be significant for corrugation angle of 60°. For corrugation angle of 30°, however, buoyancy effects were found to have some influence, yet majority of the data points are found to be within 15% of those predicted using the correlation.