A Hybrid Solar–Geothermal Heat- and Hot-Water Supply System
Tóm tắt
The cooling of rock formations when extracting heat by a borehole heat exchanger and the restoration of the thermal field in the rock during the idle time of the well have been investigated. The heat in the rock during the summer downtime of the well is partially restored due to the influx of heat from the outside formation. The radius of the rock cooling front around the borehole in the heating period can reach 6–8 m. The temperature on the borehole wall is restored by approximately 50% in one month and by 80–85% in summer. Hybrid technology is proposed for the extraction and accumulation of thermal energy from the upper layers of the earth’s crust comprised of a shallow borehole heat exchanger, a heat pump, and solar collectors. The technology provides for both the extraction of heat from the rock during the heating period and transmission of this heat to the heating system with a heat pump and the restoration of the temperature field around the well during the interheating period by accumulating in the rock formation the heat fed to the borehole heat exchanger with hot water from the storage tank. This system was implemented in Makhachkala at the test site of the Joint Institute for High Temperatures, Russian Academy of Sciences, for supplying heat and hot water to cottage-type houses. The main components of the system are solar collectors with a total area of 20 m2, a heat-insulated hot water storage tank with a built-in heat exchanger, a 15-kW heat pump, and a 100-m deep borehole heat exchanger. The test results have demonstrated high efficiency of the system for supplying heat to low-power consumers not covered by central heating.
Tài liệu tham khảo
A. B. Alkhasov, Geothermal Power Engineering: Problems, Resources, Technologies (Fizmatlit, Moscow, 2008) [in Russian].
G. P. Vasil’ev, V. F. Gornov, A. N. Dmitriev, M. V. Kolesova, and V. A. Yurchenko, “Ground source heat supply in Moscow Oblast: Temperature potential and sustainable depth of heat wells,” Therm. Eng. 65, 72–78 (2018). https://doi.org/10.1134/S0040601518010093
N. Kayaci, “Energy and exergy analysis and thermo-economic optimization of the ground source heat pump integrated with radiant wall panel and fan-coil unit with floor heating or radiator,” Renewable Energy 160, 333–349 (2020). https://doi.org/10.1016/j.renene.2020.06.150
S. S. Naicker and S. J. Rees, “Performance analysis of a large geothermal heating and cooling system,” Renewable Energy 122, 429–442 (2018). https://doi.org/10.1016/j.renene.2018.01.099
J. I. Villarino, A. Villarino, and F. Á. Fernández, “Experimental and modelling analysis of an office building HVAC system based in a ground-coupled heat pump and radiant floor,” Appl. Energy 190, 1020–1028 (2017). https://doi.org/10.1016/j.apenergy.2016.12.152
A. B. Alkhasov, M. G. Alishaev, D. A. Alkhasova, A. G. Kaimarazov, and M. M. Ramazanov, Development of Low-Potential Geothermal Heat (Fizmatlit, Moscow, 2012) [in Russian].
A. B. Alkhasov and M. G. Alishaev, “Extraction of soil heat by a borehole heat exchanger in seasonal operation mode,” Izv. Ross. Akad. Nauk, Energ., No. 2, 129–136 (2007).
A. B. Alkhasov and M. G. Alishaev, “Solar-geothermal heating system of a cottage-type house,” Izv. Ross. Akad. Nauk, Energ., No. 6, 122–132 (2011).
A. B. Alkhasov and D. A. Alkhasova, “Heating and hot water supply system based on renewable energy sources,” RF Patent No. 2445554, Byull. Izobret., No. 8 (2012).