EFFECTS OF REDUCED GRAVITY ON NUCLEATE BOILING

Abstract

An experimental study was conducted of the effects of reduced gravity on the mechanism of nucleate boiling, using a drop tower method with high speed motion pictures and a telemeter equipment. Within the range of reduced gravity up to 0. 082 g, normal nucleate boiling was observed to be insensitive to gravity, having almost the same frequency of bubble generation. The process of growth and departure of single bubbles was hardly affected by gravity, while the process after departure was gradually influenced by it. This means that not the buoyant force but the inertia of liquid is the dominant factor controlling the departureprocess. Though, at lower gravities, the coalescence of bubbles became so large as to cover a part of the heater in space or time, single bubbles insensitive to gravity were always observed at other parts of the heater in space or time, associated with little change in heat transfer characteristics.