内置弧形槽扭旋元件圆管中相变微胶囊的传热特性研究

Study on Heat Transfer Characteristics of Phase Change Microcapsules in Circular Tubes of Torsional Element With Built-in Arc Groove

设计出一种新型管内强化换热元件——弧形槽扭旋元件,在雷诺数Re=200~1 600范围内以MPCM相变流体为介质进行了管内流速场和温度场的数值模拟,基于等效比热容法从场协同角度分析了弧形槽扭旋元件的强化传热机理,并讨论了元件弧度的变化对管内换热效果的影响。结果表明:弧形槽扭旋元件可以从增强流场与温度场协同程度和提高MPCM颗粒的熔化率两方面共同增强换热效果,与传统扭旋元件相比管内Nu最高可增加12%;较低Re时,弧度r=π元件的Nu最大,而r=4π/3元件则在高Re时有着较好的换热性能;r=π元件的阻力系数最高,3种不同弧度的元件的PEC均大于1,最大值约为1.35。

A new enhanced heat transfer element, arc-shaped torsional element was designed. In the Re=200~1 600range, the MPCM phase change fluid was used as the medium to carry out numerical simulation of the flow field and temperature field in the tube. Based on the equivalent specific heat method, the heat transfer mechanism of the arc-shaped torsional element was analyzed from the field synergy perspective. The influence of element radian on heat transfer in tube was discussed. The results showed that the arc groove torsional element could enhance the heat transfer effect by enhancing the fluid disturbance and improving the melting rate of MPCM particles. Compared with the traditional torsional element, the Nu in the tube increased by up to 12%. At lower Re, the element with radian r=πhad the maximum Nu, while at higher Re, the element with radian r=4π/3 had better heat transfer performance. The element r=π had the highest resistance coefficient, and the PEC of the three elements with different radians was greater than 1, and the maximum value was about 1.35.