凝固换热器凝固换热特性模拟分析

Simulation analyses of heat transfer characteristics for freezing heat exchanger

采集凝固热热泵系统为寒冷地区地表水等热能资源的开发利用提供了新思路,其关键设备凝固换热器的换热性能直接关系到热泵系统的供热运行效率.在介绍凝固换热器及其冬季换热工况的基础上,通过定义凝固当量换热系数比等量纲一参数,采用准稳态近似与拟合等方法,对紊流状况地表水凝固换热特性进行了模拟分析,建立了刮冰周期内平均凝固当量换热系数比的统计数学模型.结果表明:入口水温与管壁温度越低、管径与Re越小、管长越大,瞬时凝固当量换热系数比越高,而凝固换热器的平均凝固当量换热系数比在1～4变化.

It is a new idea to develop and utilize the surface water heat energy by the heat pump system with freezing heat collection in the cold regions, and the heat transfer performance of the key device named freezing heat exchanger is directly related to the heating efficiency of the heat pump system. After introducing the freezing heat exchanger and its heat transfer conditions in winter, on the basis of quasi-static approximation and the fitting method, the heat transfer characteristics of the turbulent surface water are simulated and analyzed with the definition of the dimensionless parameters, such as equivalent freezing heat transfer coefficient ratio. And the statistical mathematical model of the average equivalent freezing heat transfer coefficient ratio is built up in the deicing cycle. The results show that the instantaneous equivalent freezing heat transfer coefficient ratio is greater with the lower inlet water temperature or wall temperature, the smaller diameter and Re number and the bigger tube length, while the average equivalent freezing heat transfer coefficient ratio of the freezing heat exchanger is between 1 and 4.