细小圆管内Micro-PCMS紊流对流传热特性的CFD?DPM模拟

CDF?DPM Simulation on Characteristics of Turbulent Flow and Heat Transfer for Micro-PCMS in Mini-pipe

基于计算流体动力学?离散相模型模拟研究恒热流密度条件下3D圆形管道内相变微胶囊悬浮液(Micro-PCMS)紊流的对流传热特性,讨论了微胶囊质量分数对管道内悬浮液速度、温度及壁面温度的影响,获得了沿流动方向不同截面的速度分布、温度分布及修正的局部Nu数.结果表明,靠近管道壁面处,相变微胶囊的存在使悬浮液速度降低,且随其含量增加而降低愈加明显;管内悬浮液温度分布分为非融化区、融化区和完全融化区;管道壁面温度、悬浮液出口温度均比纯水降低,相变微胶囊含量为12%,16%,20%(?)时,出口处悬浮液温度分别降低25.5%,33.9%,42.4%,壁面温度分别降低23.9%,31.0%,39.2%.且因存在相变吸热及扰动的共同效应,管道内温度分布从规则的抛物线形逐渐演变为具有尖峰的曲线.

A CFD-DPM model was used to study the characteristics of turbulent flow and heat transfer for microencapsulated phase change material slurry（Micro-PCMS） in a 3D mini-pipe at constant heat flux. The effect of Micro-PCM mass fraction on velocity and temperature of Micro-PCMS, and wall temperature was examined. Along the flowing direction, the parameters of velocity, temperature and correctional Nu number are obtained on the different cross sections. The results show that the slurry velocity near pipe wall decreases because of Micro-PCM particles, and the decrease is more obvious with the increase of content of Micro-PCM particles. Three apparent regions of non-melting region, melting region and melted region present in pipe are divided for Micro-PCMS. The pipe wall temperature and outlet temperature of the slurry are lower than those of pure water. Under three Micro-PCM mass fractions of 12%, 16% and 20%, the slurry outlet temperature is reduced by 25.5%, 33.9% and 42.4%, and the pipe wall temperature 23.9%, 31.0% and 39.2%, compared with pure water. Because of the common effect of phase change heat absorption and particle disturbance, the slurry temperature field distribution changes from regular parabola to leptokurtic curve.