一种家电用小型蒸汽发生器的传热与流动特性模拟及实验研究

Simulation and experimental research on heat transfer and flow characteristics of a small steam generator for home appliances

针对应用于各类家电中的小型蒸汽发生器的高功耗、易结垢问题,在传统使用腔体型结构上进行了改进,加大换热面积,增强换热系数,使热效率进一步提高,减小能耗。该设计可以规避一般管道型加热方式易产生的水垢阻塞流道导致换热器失效的问题。对改进型蒸汽发生器进行了热力计算及数值模拟,比较了上部进与下部进水两种方式的传热及流动特性。根据模拟结果选用具有更好的传热及流动性能的上部进水方式对增加泡沫金属铜前后的蒸汽发生器进行了实验测试,实验得到改进结构(增加金属泡沫)后蒸汽发生器的热效率可以高达98.92%,较改进前热效率约有5%的提升,改进效果明显。根据热力学原理分析,热效率的提升来自于漏热的减少和电热效率的提高。

Aiming at the problems of high power consumption and easy fouling of small steam generators used in various home appliances, this research improved the thermal efficiency of the traditional cavity structure by means of increasing the heat exchange area and enhancing the heat transfer coefficient and reduced energy consumption. At the same time, this design can avoid the problems of scale blocking the flow channel and the failure of the heat exchanger that are easily generated by the general pipeline heating method. The thermal calculation, numerical simulation and experimental verification of the improved steam generator structure were carried out. The heat transfer and flow characteristics of the upper and lower inlet water are compared by numerical simulation and results show that the upper inlet has better heat transfer and flow performance. According to the simulation results, the upper water inlet method is selected to test the steam generator before and after adding the foam metal copper. After the improved structure(adding metal foam), the thermal efficiency of the improved steam generator can be as high as 98.92%, which is about 5% higher than that before the improvement, and the improvement effect is obvious. According to the analysis of thermodynamic principle, the improvement of thermal efficiency comes from the reduction of heat leakage and the improvement of electrothermal efficiency.