Research Initiation Awards: Forced Convection Boiling Vapor Bubble Nucleation, Growth, and Departure: REU Supplement

文献中报道的大多数流动沸腾换热关联式都是利用池沸腾关联式来模拟换热的微对流部分。然而，有充分的证据表明，控制流动沸腾中蒸汽气泡的萌生、生长和离开的物理原理与池沸腾中的不同。在这种情况下，使用池沸腾关联式来模拟流动沸腾换热的微对流分量将是值得怀疑的。该研究将包括实验测量饱和强制对流成核沸腾中的成核点密度、汽泡生长速率和汽泡偏离直径。将深入研究液膜厚度、质量流量、重力取向、壁面过热度、热力学性质和受热面特性对这些参数的影响方式。用辐射吸附技术测量局部汽相体积分数和液膜厚度。成核位密度将用液晶可视化技术进行摄影测定。汽泡的生长速度和脱离直径将用高速摄影技术测量。利用所收集的实验数据，将建立流动沸腾中汽泡的萌生、生长和离开的关联式。

The majority of flow boiling heat transfer correlations reported in the literature utilize pool boiling correlations to model the microconvection component of heat transfer. However, there appears sufficient evidence that the physics governing the incipience, growth, and departure of vapor bubbles in flow boiling differs from that in pool boiling. Under such circumstances, the use of pool boiling correlations to model the microconvection component of flow boiling heat transfer would be questionable. The proposed investigation will consist of experimentally measuring the nucleation site density, vapor bubble growth rate, and vapor bubble departure diameter in saturated forced convection nucleate boiling. The manner in which the liquid film thickness, mass flux, gravitational orientation, wall superheat, thermodynamic properties, and heating surface characteristics influence these parameters will be thoroughly investigated. The local vapor volume fraction and liquid film thickness will be measured using a radiation adsorption technique. The nucleation site density will be determined photographically in conjection with a liquid crystal visualization technique. The vapor bubble growth rate and departure diameter will be measured using high speed cinematography. Using the experimental data to be collected, correlations for the incipience, growth and departure of vapor bubbles in flow boiling will be developed.