直接接触换热器中分散相单个气泡的传热机理研究

Heat Transfer Mechanism of a Single Dispersed Phase of Bubbles in Direct Contact Heat Transfer

基于能量微分方程和质量守恒定律,通过对分散相单个气泡在连续相溶液中的直接接触换热理论分析,建立了分散相单个两相气泡在液体连续相中直接接触换热的传热和气泡生长数理模型.得出了单个气泡在其表面上的平均瞬时换热系数和换热的努谢尔特准则数计算公式,并推导出气泡生长速率的计算关联式.此外,对气泡生长速率的主要影响因素进行分析得出:气泡的生长速率是随速度U和温差ΔT的增加而增大,且增加的速率在前期较快,随后逐渐减慢;气泡的生长速率是随初始半径的增加,先增大后减小的.

Through theoretical analysis,this paper establishes the mathematical model of direct contact heat transfer and bubble growth for a single dispersed two phase of bubble.Then the average instantaneous heat transfer coefficient of a single bubble on its surface,Nusselt number calculation formula and the computation correlations of bubble growth rate are deduced.It is found through the analysis that the bubble growth rate increases with the increase of the speed U and of the temperature difference ΔT and that the rate grows faster in the earlier stage and slower thereafter.In relation to the growth of the initial radius,the bubble growth rate increases first and then decreases.