Nucleate pool boiling from coated surfaces in saturated R-134a and R-407c

Pool nucleate boiling heat transfer experiments from coated surfaces immersed in saturated R-134a and R-407c with porous aluminum, copper, molybdenum, and pitted coating on a copper surface were conducted. The influence of coating thickness and porosity on heat transfer and boiling hysteresis were studied. The enhanced surface heat transfer coefficients are 2.5 times higher than those of the smooth surface. Furthermore, the effects of refrigerant thermophysical properties are also presented and discussed. The experimental data for plasma and flame spray coating surfaces were correlated in terms of the Reynolds number based on a mean pore diameter and porosity, Jakob number, constant heat flux number and geometric scale factor to provide a thermal design basis for engineering application. Copyright (C) 1996 Elsevier Science Ltd.