热孤子与微细通道相变传热研究

Investigation into Heat Soliton and Phase-Change Heat Transfer in Minichannel

针对微槽流动相变传热,在给出气泡平衡半径及初值条件的前提下,提出了气泡在微槽中演化半径的系综公式,结合气泡生长随机变量的相关性得出了气泡在微槽中生长所满足的随机微分动力方程,由方程的定态解进一步得出了微槽中气泡生长系统的势能及概率密度函数随半径的演化规律.根据微槽中反应气泡热通量的热孤子表达式,从理论上获得了以核态沸腾为主的微槽相变传热计算公式,并对具有23条平行的0.3mm×2mm微槽进行了相变传热实验.理论计算值与实验结果较吻合,误差小于7%,验证了该公式的可行性.

This paper deals with the phase-change heat transfer in a minichannel. In the investigation, first, an ensemble formula is put forward to calculate the average evolution radius of bubbles based on the known bubble equilibrium diameter and initial value. Next, a random dynamic differential equation describing the growth of bubbles in the minichannel is deduced based on the correlations of random growth factors and the proposed ensemble formula. Then, the potential energy and probability density of the bubble growth system varying with the radius are obtained according to the steady-state solution to the proposed dynamic equation. Furthermore, a formula describing the phase-change heat transfer with nucleate flow boiling is put forward according to the heat soliton expression describing the heat flux of reaction bubbles in the minichannel. Finally, some phase-change heat transfer experiments are carried out for 23 parallel minichannels with the size of 0.3 mm × 2 mm. It is indicated that the proposed formula is feasible because the theoretical results accord well with the experimental ones with an error of less than 7 %.