Long-term Experiment of Hot Spring Heat Recovery Using Rotary Heat Exchanger by Controlling Precipitation

Abstract

To establish a low-carbon society, it is necessary to break away from dependence on fossil fuels, and the utilization of geothermal energy/waste heat is one of the key methods. When using geothermal energy, the rate of heat transfer decreases with time due to the precipitation of scale on the heat transfer surface, and periodic maintenance is required. Therefore, the running cost of utilizing geothermal energy is high. We focused on a rotary heat exchanger consisting of a rotating cylinder as the heat transfer wall and a fixed blade attached to the rotating cylinder for scraping the heat transfer surface. In this study, the heat recovery characteristic from chloride hot spring was experimentally evaluated. The results showed that scale formation on the heat transfer surface could be suppressed and the heat transfer characteristics could be maintained for one month.

Numerical thermal–hydraulic analysis and multiobjective design optimization of a printed circuit heat exchanger with airfoil overlap fin channels

“…It is important to note that the Reynolds number of both schemes are set at 1088, if not otherwise specified, and the inlet temperatures of the hot and cold streams are set at 90 and 30°C, respectively. When choosing the inlet temperatures for both hot and cold streams, we carefully considered the temperatures observed in real hot springs within the temperature range employed in a relevant study conducted by Maruoka et al 29 …”