Kaneyasu Nishikawa

Some Remarks on the Measurement of Coefficient of Heat Transfer to Boiling Liquids

On the heat transfer to boiling liquids many investigations were carried out, but their results indicated no satisfactory coincidence. It arises from the existence of the mutal dependence between the generation of vapour bubbles and the flowing condition of liquids. The properties of heating surface, which influence directly on the generation of vapour bubbles have been hitherto discussed, but the heat loss from the side-wall of experimental apparatus has been out of consideration. This heat loss may influence on the flowing condition of liquids and the generating state of vapour bubbles. In this experiment we investigated the influence of heat loss from the side-wall of experimental apparatus on the coefficient of heat transfer. Experiments were carried out as follows : (1) heater ; upwards horizontal metal heating surface (dia. 10 cm) (2) liquids : distilled water (3) heat flux : 6560∼19690 kcal/m2h (4) jacket water temperature : 90∼100°C And we found that the heat loss from the side-wall of experimental apparatus influenced greatly on the coefficient of heat transfer to boiling liquids. Therefore, one must take care of this heat loss on the measurement of coefficient of heat transfer to boiling liquids.