为了得到适用于微小通道内流动沸腾换热的预测方法,本文以近些年发表的9篇文献中的2924个实验数据点组成数据库,考虑到随着通道直径减小,表面张力对微小通道内两相流动和换热的影响起到主要作用,将Chen形式的换热模型中的核态沸腾和对流换热两部分的修正系数进行了优化。沸腾抑制系数和对流增强系数由气相韦伯数、两相雷诺数、沸腾数、气泡抑制数等量纲为1数组成,反映出了表面张力、水力直径、流动条件、热力条件对于换热的综合影响。结果表明,拟合出的微小通道中沸腾换热的新模型,适于预测水力直径3 mm以下的细管道中CHF(临界热流密度)点以前的换热系数。与实验数据比较,新模型预测的平均绝对误差为19.0%。
In order to get a method for predicting the flow boiling heat transfer in mini-channels,2924 experimental data of flow boiling in mini-channels from 9 literatures were analyzed.As the tube diameter decreases,the surface tension rather than the buoyancy affects the two phase flow and heat transfer.The enhancement factor of convective evaporation and suppression factor of nucleate boiling of Chen-type correlation were optimized.The non-dimensional number vapor Weber number,two-phase Reynolds number,boiling number and confinement number were used to express the effects of surface tension,diameter,flow conditions and heat flux.A new model was presented to predict the heat transfer coefficient of pre-dryout in mini-channels.A mean absolute deviation of 19.0% was achieved with this new correlation.