Abstract
An experimental study of heat transfer characteristics near the critical pressure has been performed with a vertical 5x5 heater rod bundle cooled by Freon 134a fluid. The CHF has been measured in a range of the pressure of 3.20〜4.03MPa (the critical pressure of Freon 134a is 4.059MPa). The critical power decreases sharply with the system pressure near the critical pressure and shows a trend towards converging to zero as the pressure approaches the critical point. The CHF phenomenon near the critical pressure no longer leads to an inordinate increase in the heated wall temperature such as the case of the DNB at normal pressure conditions. The existence of a threshold pressure at which the CHF phenomenon disappears has been observed near the critical pressure.
