E3S Web Conf.
Volume 205, 20202nd International Conference on Energy Geotechnics (ICEGT 2020)
|Number of page(s)||6|
|Section||Issues Related to Energy Piles|
|Published online||18 November 2020|
Thermal response of energy foundations installed in unsaturated residual soils
1 University of Illinois at Urbana Champaign, Department of Civil and Environmental Engineering, USA
2 University of São Paulo at São Carlos, Department of Geotechnical Engineering, Brazil
* Corresponding author: firstname.lastname@example.org
This study focuses on the thermal response of energy foundations with different piping geometries installed in unsaturated soil. Energy foundations are an efficient alternative to traditional space heating and cooling approaches and can reduce energy demand for air conditioning in Brazil, where unsaturated residual soil deposits are abundant. A three-dimensional numerical model for heat transfer and subsurface flow is first validated against field data from a thermal response test at the University of São Paulo. The model is then used to compare the performance of triple and quadruple U-tube piping geometries and helical piping geometries of equivalent length. The helical geometries resulted in initial less uniformly heated foundations and lower heat flux at the foundation boundary compared with the U-tubes, but the differences between the U-tube geometries and their equivalent length helices were less than 1°C. All piping geometries exhibited increased heat output as the length of heat exchanger piping increased. The infinite line source solution was compared with the model results. The infinite line source solution underestimated the thermal response of the system during the first 25-30 days and overestimated it afterwards.
© The Authors, published by EDP Sciences, 2020
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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