An Experimental Study of the Pool-Boiling CHF on Downward-Facing Plates

Abstract

An experimental study has been peformed on the pool-boiling critical heat flux (CHF) phenomenon on downward -facing plates. The CHF for inclinations of -90(horizontally downward position), -88, -86, -84, -60 and -40 were measured using plate-type test sections of 20mm 200mm and 25mm 200mm in a pool of saturated water under atmospheric pressure. The measured CHF was lower for the wider test section and decreased as its orientation approached to the horizontally downward position. The lower CHF can be attributable to the increased difficulty for the bubbles in escaping from the heater surface. When compared with the previous works, the overall trends were similar; however, a transition angle, at which the decrease rate in the CHF was changed, was observed in the vicinity of -80.