NUCLEATE POOL BOILING FROM COATED SURFACES IN SATURATED R-134A AND R-407C

Pool nucleate boiling heat transfer experiments from coated surfaces i mmersed in saturated R-134a and R-407c with porous aluminum, copper, m olybdenum, and pitted coating on a copper surface were conducted. The influence of coating thickness and porosity on heat transfer and boili ng hysteresis were studied. The enhanced surface heat transfer coeffic ients are 2.5 times higher than those of the smooth surface. Furthermo re, the effects of refrigerant thermophysical properties are also pres ented 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 flu x number and geometric scale factor to provide a thermal design basis for engineering application. Copyright (C) 1996 Elsevier Science Ltd.