Many people don't know that the household appliances we see everywhere in our daily lives hide the figure of small steam generators behind them: the delicate steam sprayed by steam irons, the high-temperature water vapor used to soften stains in steam washing machines, and the hot steam used to lock in food moisture in steam microwaves. The core components of these functions are small electric heating steam generators with small volumes. In the past, such small equipment commonly had problems with low thermal efficiency and easy scaling and blockage. However, the technological breakthroughs of domestic research teams have completely broken through this long-standing bottleneck in the industry, enabling a qualitative leap in the performance of small steam generators.

The R&D team of the Institute of Refrigeration and Cryogenics at Zhejiang University has made a groundbreaking structural innovation to address the pain points of traditional small cavity steam generators. Traditional small steam generators mostly adopt the design of directly heating the water in the chamber, which not only has low heat transfer efficiency, but also makes the inner wall easy to scale after long-term use. When the scale accumulates to a certain extent, it will block the flow channel and directly lead to equipment failure. The R&D team jumped out of the traditional design idea, wrapped a layer of porous metal foam material outside the U-shaped electric heater, and installed a liquid distributor at the water inlet, so that the water flowing into the equipment is evenly distributed on the surface of the metal foam. This seemingly simple modification directly enlarges the heat exchange area between water and heater by dozens of times, resulting in a qualitative improvement in heat exchange efficiency.

In order to verify the performance of the new structure, the R&D team compared the operating effects of two different schemes, upper inlet and bottom inlet, through numerical simulation. The simulation results show that the thermal efficiency of both water inlet methods can reach over 95%, with the upper water inlet scheme performing more outstandingly: the temperature gradient distribution inside the equipment is more uniform, and there will be no local low-temperature areas. The final steam produced has a dryness of 1 and directly enters the superheated state. The outlet temperature remains stable between 135 ℃ and 140 ℃, fully meeting the high temperature steam demand of household appliances. The bottom inlet scheme can also achieve a steam dryness of 0.99 and a stable temperature of 100 ℃ at the outlet, making it suitable for scenarios with a demand for saturated steam.

The subsequent laboratory test data further validated the superiority of the new structure. The R&D team built a professional performance test platform, used a liquid peristaltic pump with an accuracy of 0.1 mL/min to control the water inflow, matched with a thermocouple with an accuracy of 0.1 ℃ to monitor the temperature in real time, and compared the operating data of two steam generators before and after the installation of metal foam. The final experimental results show that the thermal efficiency of the improved steam generator using metal foam to enhance heat transfer reaches 98.92%, which is more than 5 percentage points higher than the thermal efficiency of the traditional cavity structure. At the same time, the problem of easy scaling and blocking in long-term operation is completely solved. Metal foam components can also be directly disassembled and cleaned, and the maintenance cost is significantly reduced.