Nucleation and Critical Heat Flux in Spray Cooling

。9616344 Chow，Louis C.摘要本提案涉及用于高热流密度应用的喷雾冷却。主要研究人员建议从实验上确定强迫对流、表面空腔的核沸腾和由撞击液滴包裹的空气/蒸汽核引起的二次核沸腾的相对重要性。一台高速摄像机将与半透明的合成钻石薄膜结合使用，以可视化沸腾过程。为计算核态沸腾对喷雾冷却的贡献，需要确定相应的参数，如气泡密度、生长速率等。二次成核沸腾的贡献将通过比较成核特性与无二次成核的浸没射流下的成核特性来确定。

. 9616344 Chow, Louis C. ABSTRACT This proposal deals with spray cooling for high heat flux applications. The principal investigators propose to experimentally determine the relative importance of forced convection, nucleate boiling from surface cavities, and secondary nucleate boiling due to air/vapor nuclei entrapped by the impinging droplets. A high-speed camera will be used in conjunction with a semi-transparent synthetic-diamond film to visualize the boiling process. Relevant parameters such as the bubble density, growth rate, etc. will be determined for calculating the contribution of nucleate boiling in spray cooling. The contribution of secondary nucleate boiling will be established by comparing the nucleation characteristics with that conducted with a submerged jet where secondary nucleation is absent.