Experimental investigation on the characteristics of maximum bubble size of subcooled flow boiling in narrow rectangular channel under different system pressure

摘要

The size and distribution of bubbles in subcooled boiling have considerable influence on boiling heat transfer. In this paper, subcooled flow boiling experiment is carried out to investigate the maximum diameter and distribution characteristics of bubbles under different system pressure, and the test section is full transparent. Since the whole body of the test section is composed of transparent materials (sapphire crystal and quartz glass), it can be observed from different directions to obtain high quality images. Two kinds of maximum bubble diameters are found during bubble sliding and condensation, respectively. Besides, the results show that both the distributions of maximum bubble slide diameter and maximum bubble condensation diameter are lognormal distribution in this work. Finally, models of maximum bubble slide diameter and maximum bubble condensation diameter are proposed and verified by the experimental result. Good agreement is obtained when comparing the predicted maximum bubble diameter with the experimental result. The average relative errors are 31.1% and 26.9%, respectively.