Heat Transfer in Surface Boiling under Free Convection

抄録

Through an experiment of nucleate boiling under free convection in subcooled water, we came to the following conclusions : (1) The effective stirring length of bubbles in surface boiling is reasonably estimated to be one-third of their condensing height which is determined identically with the dgree of subcooling of bulk water. (2) Correlation of heat transfer in surface boiling using Δθ_s instead of Δθ corresponds to the replacing of H_e by H_es, where Δθ_s : temperature difference between heating surface and saturated liquid, Δθ : temperature difference between heating surface and bulk liquid, H_e : effective stirring length of bubbles in saturated boiling, H_es : effective stirring length of bubbles in surface boiling. From these conclusions, we derived an extension of author's correlating equation of nucleate boiling heat transfer, and confirmed that it fairly agreed with the experimental results in surface boiling.