Heat Transfer in Soft Clay: Pilot-Scale Experiment Using Solar Collectors
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 148, Issue 8
Abstract
This work introduces a pilot-scale experiment conducted for 18 months to study the soil heating performance of solar collectors in Japan for borehole thermal energy storage and thermal consolidation applications. In this experiment, water was heated using a solar collector and then circulated in three heat exchangers inserted into a box of kaolin clay installed in sandy ground. The solar collector had a heat collection area of and was attached to a 200-L water tank. The tank containing the clay was internally lined by a 6-cm-thick box of polyethylene foam to reduce heat exchange with the environment. The average clay temperature reached a maximum value of 41.1°C in the summer and a minimum of 14.9°C in the winter. The circulation water temperature varied seasonally between a daytime maximum of 77.5°C in summer and a daytime minimum of 22.5°C in winter. The experiment was simulated using a finite-element analysis model based on thermal conduction. The model used the Dittus–Boelter equation to model the heat exchangers’ energy output and adopted an environmental heat exchange boundary condition using ambient temperature, wind speed, and total daily solar flux data. The numerical results accurately predicted the ground and average kaolin temperature within a 2°C–3°C margin of error. The numerical and experimental spatial distributions of kaolin temperature suggest that gravity and temperature-induced moisture transport was sufficient to measurably change the kaolin water content. Additionally, the numerical results of the sandy ground temperature revealed its sensitivity to variation of moisture content induced by evapotranspiration. Last, changing the boundary condition of the kaolin box to thermal insulation revealed that environmental heat loss accounted for a 13.5°C–19.5°C difference in the average kaolin temperature between the numerical and experimental results, emphasizing the importance of adequate thermal insulation in ground heating applications.
Get full access to this article
View all available purchase options and get full access to this article.
Data Availability Statement
Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request. These data include kaolin and flow temperature, flow rate, and weather data.
Acknowledgments
We would like to thank Mr. Kazuki Yamaguchi and Mr. Shuhei Nishi (formerly Kyoto University) for their valuable contribution to the setup and analysis of the experiment. We extend our gratitude to Dr .Yoshikazu Otsuka (Okumura Corporation) for his contribution to deepening the discussion. We are also grateful to Dr. Shinichiro Shiraga, Mr. Shinji Yamasaka, and Mr. Yoshifumi Yamauchi (Kinjo Rubber Co., Ltd.) for hosting the experiment in their factory and for their support with the design, setup, operation, data acquisition, and analysis of the experiment. This work was supported by JSPS KAKENHI Grant No. JP18K13828.
References
Abed, A. A., and W. T. Sołowski. 2017. “A study on how to couple thermo-hydro-mechanical behaviour of unsaturated soils: Physical equations, numerical implementation and examples.” Comput. Geotech. 92 (Dec): 132–155. https://doi.org/10.1016/j.compgeo.2017.07.021.
Abuel-Naga, H. M., D. T. Bergado, and A. Bouazza. 2007. “Thermally induced volume change and excess pore water pressure of soft Bangkok clay.” Eng. Geol. 89 (1–2): 144–154. https://doi.org/10.1016/j.enggeo.2006.10.002.
Başer, T., and J. S. McCartney. 2020. “Transient evaluation of a soil-borehole thermal energy storage system.” Renewable Energy 147 (2): 2582–2598. https://doi.org/10.1016/j.renene.2018.11.012.
Bergado, D. 1996. Soft ground improvement: In lowland and other environments. New York: ASCE Press.
Coccia, C. J. R., and J. S. McCartney. 2016. “Thermal volume change of poorly draining soils I: Critical assessment of volume change mechanisms.” Comput. Geotech. 80 (Dec): 26–40. https://doi.org/10.1016/j.compgeo.2016.06.009.
Cooper, P. I., and R. V. Dunkle. 1981. “A non-linear flat-plate collector model.” Sol. Energy. 26 (2): 133–140. https://doi.org/10.1016/0038-092X(81)90076-1.
Engineering ToolBox. 2003. “Emissivity coefficient materials.” Accessed October 4, 2021. https://www.engineeringtoolbox.com/emissivity-coefficients-d_447.html.
Gabrielsson, A., L. Marti, M. Lovisa, B. Ulf. 1997. Heat storage in soft clay. Linköping, Sweden: Swedish Geotechnical Institute.
Ghaaowd, I., A. Takai, T. Katsumi, and J. S. McCartney. 2017. “Pore water pressure prediction for undrained heating of soils.” Environ. Geotech. 4 (2): 70–78. https://doi.org/10.1680/jenge.15.00041.
Hansbo, S. 1979. “Consolidation of clay by band shaped prefabricated drains.” Ground Eng. 12 (5): 16–25.
Incropera, F. 2007. Fundamentals of heat and mass transfer. Hoboken, NJ: Wiley.
Kirsch, K., and A. Bell. 2013. Ground improvement. Boca Raton, FL: CRC Press.
Kyuma, K. 1985. “Soil temperature regime of Japanese soils.” Soil Sci. Plant Nutr. 31 (3): 463–468. https://doi.org/10.1080/00380768.1985.10557453.
Laloui, L., and C. Cekerevac. 2003. “Thermo-plasticity of clays.” Comput. Geotech. 30 (8): 649–660. https://doi.org/10.1016/j.compgeo.2003.09.001.
Monteith, J. L. 2013. Principles of environmental physics. 4th ed. Oxford: Academic Press.
Moradi, A., K. M. Smits, N. Lu, and J. S. McCartney. 2016. “Heat transfer in unsaturated soil with application to borehole thermal energy storage.” Vadose Zone J. 15 (10): 1–17. https://doi.org/10.2136/vzj2016.03.0027.
Nordell, B., and G. Hellström. 2000. “High temperature solar heated seasonal storage system for low temperature heating of buildings.” Sol. Energy 69 (6): 511–523. https://doi.org/10.1016/S0038-092X(00)00120-1.
Ogawa, A., A. Takai, T. Shimizu, and T. Katsumi. 2020. “Effects of temperature on consolidation and consistency of clayey soils.” In E3S Web of Conf., edited by J. S. McCartney and I. Tomac. Les Ulis, France: EDP Sciences. https://doi.org/10.1051/e3sconf/202020509010.
Ouzzane, M., P. Eslami-Nejad, Z. Aidoun, and L. Lamarche. 2014. “Analysis of the convective heat exchange effect on the undisturbed ground temperature.” Sol. Energy 108 (Oct): 340–347. https://doi.org/10.1016/j.solener.2014.07.015.
Pothiraksanon, C., D. T. Bergado, and H. M. Abuel-Naga. 2010. “Full-scale embankment consolidation test using prefabricated vertical thermal drains.” Soils Found. 50 (5): 599–608. https://doi.org/10.3208/sandf.50.599.
Pothiraksanon, C., D. T. Bergado, H. M. Abuel-Naga, S. Hayashi, and Y. J. Du. 2007. “Novel thermo-PVD consolidation technique for soft soils.” Lowland Technol. Int. 9 (2): 38–48.
Rao, K. G. 2004. “Estimation of the exchange coefficient of heat during low wind convective conditions.” Bound.-Layer Meteorol. 111 (2): 247–273. https://doi.org/10.1023/B:BOUN.0000016495.85528.d7.
Samarakoon, R., and J. McCartney. 2020. “Analysis of thermal drains in soft clays.” Accessed November 1, 2021. https://par.nsf.gov/biblio/10251002.
Sánchez, M., A. Gens, M. V. Villar, and S. Olivella. 2016. “Fully coupled thermo-hydro-mechanical double-porosity formulation for unsaturated soils.” Int. J. Geomech. 15 (6): D4016015. https://doi.org/10.1061/(ASCE)GM.1943-5622.0000728.
Stull, R. B. 2000. Meteorology for Scientists and Engineers. Pacific Grove, CA: Brooks/Cole.
Wong, B., and L. Mesquita. 2019. “Drake landing solar community: Financial summary and lessons learned.” In Proc., ISES Solar World Congress 2019. Freiburg im Breisgau, Germany: International Solar Energy Society. https://doi.org/10.18086/swc.2019.11.03.
Information & Authors
Information
Published In
Copyright
© 2022 American Society of Civil Engineers.
History
Received: Nov 19, 2021
Accepted: Apr 1, 2022
Published online: May 30, 2022
Published in print: Aug 1, 2022
Discussion open until: Oct 30, 2022
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.