HEAT TRANSFER FROM A SMALL, HIGH-HEAT-FLUX PATCH TO A SUBCOOLED TURBULENT FLOW.

An experimental investigation of heat transfer from a small heated patch to a subcooled, fully-developed turbulent flow was conducted. The test patch, approximately 0. 25 mm long and 2. 0 mm wide, is located on the floor of a small rectangular channel through which a coolant (R-113 or FC-72) is circulated. A thin film of Nichrome deposited on a quartz substrate serves as an integrated heater element and a resistance thermometer. The results obtained with FC-72 show large temperature overshoots and a boiling hysteresis near the onset of nucleate boiling. The nucleate boiling regime spans over a short range in heat flux at low velocity and low subcooling.