波纹结构参数对搪瓷蓄热元件传热及流动特性的影响

Influence of waviness structural parameters on heat transfer and fluid flow characteristics of enamel heat storage elements

为了缓解回转式空气预热器积灰和低温腐蚀,大部分电厂在空气预热器冷端采用搪瓷蓄热元件。本文利用数值模拟方法对一种常用的搪瓷蓄热元件进行分析,研究其传热及流动特性随波纹高度与宽度等结构参数的变化规律,从而优化蓄热元件设计。研究结果表明:增大搪瓷蓄热元件波纹高度和宽度,有助于强化传热,但同时使流动阻力增大,且随着波纹高度和宽度的增加,阻力系数f增幅远大于努塞尔数Nu的增幅;在回转式空气预热器内部布置空间充裕的情况下,可通过适当减小波纹高度和宽度,获得搪瓷蓄热元件良好的流通特性,从而减小送、引风机电耗,降低电厂运行成本。

Aiming at alleviating dust accumulation and low temperature corrosion occurred on rotary air pre- heaters,most power plants adopt enamel heat storage elements at cold end of the air preheater. The change rules of heat transfer and flow characteristics of the fluid versus the structural parameters of a commonly used heat storage element such as wave height and width were numerically studied, to optimize the enamel storage element design. The results show that, enlarging the waviness height and width can enhance the heat transfer,but the flow resistance will also increase,especially, with an increase in the waviness height and width,the growth rate of the flow resistance coefficient is far higher than that of Nusselt number. When the space in the rotary preheater is enough, it should properly decrease the waviness height and width to obtain a well flow characteristics of the fluid,thus to reduce the energy consumption of the forced and induced draft fan and minimize the operation cost.