Recently there has been a demand for a hot water generator to be made more compact while offering high thermal performance for application in intelligent house and buildings. The authors have developed a new hot water generator capable of controlling the hot water temperature and heat output. This generator comprises a loop heat pipe having a control valve and thermal storage blocks.
With this system, heat is charged into the ceramic thermal storage blocks by small electric heaters for the period of several hours at night. During this time, as the evaporator of the heat pipe is completely dried out, the maximum thermal storage temperature is able to reach about 500 deg. C. When it is necessary to obtain hot water, the heat pipe valve and the water supply valve are open simultaneously. Then, after a few seconds elapse, hot water is supplied. The hot water temperature can also be freely controlled. This performance is due to the fast thermal response of the heat pipe and control of the working fluid by a valve.
This system has the following advantages; compactness, high thermal response, accurate control of the hot water temperature, and safe operation. What's more, there is no fear of steam generation during the heat pipe operation. It is expected that the hot water generator will be put into practical use in the near future as the substitute for a conventional hot water storage system.