Abstract: 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.

Key words: Small-scale stream generator, Heat transfer, Flow, Numerical simulation, Experimental research