竖直矩形细通道内的水沸腾换热特性

以宽度为1.0 mm和0.1 mm的竖直矩形细通道内的沸腾换热特性为研究对象,运用数值模拟的方法探索气泡生成、长大和脱离的过程,通过几何重构和界面追踪的方法获取相界面移动和变化对系统内压差以及平均表面换热系数的影响。计算中考虑重力、表面张力和壁面黏性的作用。研究结果表明:通道宽度的不同对气泡生长方式和气泡形态产生很大影响,且核态沸腾换热系数随着细通道宽度的减小而增大;表面张力在细通道沸腾换热过程中所起的作用明显增大,证明细通道有强化换热的作用;由于数值计算中进行了理想化假设,导致数值模拟的沸腾传热系数比现有细通道沸腾传热实验传热系数普遍偏高。

Nucleate boiling heat transfer in vertical rectangular mini-channel

In order to study the characteristics of boiling two-phase heat transfer in vertical rectangular mini-channels with width of 1.0 mm and 0.1 mm,a numerical simulation was conducted to explore the course of bubble generation,growing up and departure from the wall.Gravity,surface tension and the wall adhesion were taken into consideration,the effect caused by the interface movement on the system pressure difference and the average surface heat transfer coefficient was also discussed by using the geometry reconstruction and interface tracking method.The results show that the variation of channel width has great influence on the course of bubble growth and motion.As the channel size decreases,the nucleate boiling heat transfer coefficient increases obviously,proving that the mini-channel can enhance the heat transfer.However,due to some idealized assumptions,the boiling heat transfer coefficient of the numerical simulation is higher than the existing experimental value.