斯特林发动机回热器流动和传热特性研究

发布时间：2018-04-30 15:36

本文选题：回热器 + 压降　；参考：《南京航空航天大学》2014年硕士论文

【摘要】：碟式热发电系统由于其自身的灵活性及转换效率高等优点,成为太阳能利用中最具潜力的发电方式之一。回热器在其核心设备—斯特林发动机中起着重要的节能作用,其优良程度直接影响整个系统的工作性能。因此有关回热器的研究成为一个越来越重要的课题。本文采用多孔介质模型,数值分析了回热器内部的流动和传热变化规律。工作稳定后,回热器热冷端压力无相位差,压降呈正弦规律变化;回热器基体轴向温度近似成线性分布;热冷端温度大致呈波浪形变化。本文还对回热器参数进行了改变,模拟发现铜丝网回热器的温度分布曲线较不锈钢的更加平坦,基体温度呈现出整体上升性;回热器的热冷端压降随频率的增加而增大,低频率下回热器的换热效果更好。文中还提出一个考虑填料种类因素的正比于换热能力反比于单位长度压降的综合性能参数,并以该参数对回热器基体进行分层研究,得出将大孔隙率高导热系数的材料填充回热器热端,将小孔隙率低导热系数材料的丝网置于冷端,不但能减小回热器流动阻力损失,还能提高其效率,从而增大其综合性能参数;这种布置下的回热器,内部流阻损失主要集中在后半段;稳定后在基体的前半段和后半段各形成了一个接近线性的温度梯度,前半段的温度分布较为平缓,后半段的温度梯度较大;且两层式基体的最差分层位置在距离回热器热端45mm处,分层点越远离这个区域其流动和传热的综合特性越好。
[Abstract]:Because of its flexibility and high conversion efficiency, disc thermal power generation system has become one of the most potential power generation methods in solar energy utilization. The regenerator plays an important role in saving energy in the Stirling engine, which has a direct impact on the performance of the whole system. Therefore, the research of regenerator has become a more and more important subject. In this paper, the flow and heat transfer in the regenerator are numerically analyzed by using the porous media model. After stable operation, the pressure at the thermal end of the regenerator has no phase difference, and the pressure drop is sinusoidal; the axial temperature of the regenerator matrix is approximately linear distribution; the temperature of the hot end of the regenerator is approximately wave-shaped. The temperature distribution curve of copper wire mesh regenerator is more flat than that of stainless steel, and the matrix temperature is rising as a whole, and the pressure drop at the hot cold end of the regenerator increases with the increase of frequency, and the temperature distribution curve of the regenerator is changed in this paper, and it is found that the temperature distribution curve of the regenerator is flatter than that of stainless steel. The heat transfer effect of the regenerator is better at low frequency. A comprehensive performance parameter, which is proportional to the heat transfer capacity and inversely proportional to the pressure drop per unit length, considering the type of filler, is proposed, and the stratification of the regenerator matrix is studied by this parameter. It is concluded that filling the hot end of the regenerator with the material with large porosity and high thermal conductivity and placing the wire mesh of the material with small porosity and low thermal conductivity at the cold end can not only reduce the flow resistance loss of the regenerator, but also improve its efficiency. The internal flow resistance loss of the regenerator under this arrangement is mainly concentrated in the second half, and a linear temperature gradient is formed in the first half and the second half of the matrix after stabilization. The temperature distribution in the first half is relatively smooth and the temperature gradient in the second half is larger, and the worst stratification position of the two-layer matrix is located at the 45mm from the hot end of the regenerator. The better the comprehensive characteristics of the flow and heat transfer are, the farther the delamination point is away from this region.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM615

【共引文献】