Numerical Study on Energy Pile Groups with Deep Penetration 1-U-Shape Heat Exchangers under Different Operation Modes
Publication: International Journal of Geomechanics
Volume 23, Issue 12
Abstract
Energy piles, as an environmentally friendly means to exploit renewable energy, have attracted the attention of global researchers over the past years. Traditional heat exchanger configurations (1-U-shape, 1-W-shape, and multi-U-shape in series or parallel) have been utilized. Traditional 1-U-shape is limited by pile length, short heat transfer path, and low total heat transfer rate. Traditional 1-W-shape heat exchange tubes will cause thermal interference. Moreover, the heat exchange rate per unit tube length is not high for multi-U-shape in series or parallel. Therefore, this paper presents an efficient pile foundation heat exchanger configuration, i.e., deep penetration 1-U-shape configuration. Through a numerical study, energy pile groups with deep penetration 1-U-shape heat exchangers are investigated under continuous operation mode and intermittent operation mode. The temperature change of the piles and soil under intermittent operation mode is analyzed. Thermal performances (e.g., outlet water temperature and heat transfer efficiency) are compared under the two operation modes. Four typical monitoring points under the two operation modes are compared, and the difference in temperature variation is obtained to study the influence on the temperature field of the piles and soil. Results show that in summer mode, the temperature of the pile under intermittent operation mode presents restorability while the temperature of the soil increases gradually. Intermittent operation mode yields a lower temperature of outlet water temperature than continuous operation mode does, and therefore intermittent operation mode is recommended.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
This research was supported by the Hubei Technological Innovation Special Fund (Grant Nos. 2017AAA128 and 2018AAA028). This support is gratefully acknowledged.
Author contributions: Conceptualization, Weidong Lyu; methodology, Min Xia and Mingjian Liu; software, Zhangshuo Luo and Dingbao Song; formal analysis, Weidong Lyu; writing—original draft preparation, Weidong Lyu and Min Xia; writing—review and editing, Weidong Lyu and Min Xia; and supervision, Weidong Lyu. All authors have read and agreed to the published version of the manuscript.
Notation
The following symbols are used in this paper:
- A
- cross-sectional area of the tube (m2);
- A0
- maximum annual amplitude of temperature (K);
- cs
- specific heat capacity (J/kg · K);
- cw
- specific heat capacity of water (J/kg · K);
- D
- hydraulic diameter of the tube (m);
- d
- damping depth of annual fluctuation of temperature (m);
- div
- divergence operator;
- fd
- friction factor;
- grad
- gradient operator;
- hint
- convective heat transfer coefficient inside the tube (W/m2 · K);
- (hZ)eff
- thermal transmittance of the tube (W/K);
- kDf
- shape factor related to tube’s curvature;
- ks
- thermal conductivity (W/m · K);
- kt
- thermal conductivity of the tube (W/m · K);
- kw
- thermal conductivity of water (W/m · K);
- p
- water pressure (Pa);
- Qwall
- exchanged heat transfer rate per unit of length through the tube wall (W/m);
- r0
- internal radii of the tube (m);
- r1
- external radii of the tube (m);
- T
- temperature (K);
- Tave
- annual average temperature (K);
- Text
- pile temperature (K);
- Tin
- inlet water temperature (K);
- Tout
- outlet water temperature (K);
- t
- time (day);
- t
- time (s);
- u
- flow velocity of water (m/s);
- |u|
- norm of water flow velocity (m/s);
- v
- volumetric flow rate of water (m3/s);
- z
- depth (m);
- Δm
- water mass per unit time (kg/s);
- ω
- annual radial frequency (1/day);
- ρs
- density of soil or pile (kg/m3); and
- ρw
- density of water (kg/m3).
References
Abdelaziz, S. L., C. G. Olgun, and J. R. Martin II. 2011. “Design and operational considerations of geothermal energy piles.” In Geo-Frontiers 2011: Advances in Geotechnical Engineering, 450–459. Reston, VA: ASCE.
Abdelaziz, S. L., and T. Y. Ozudogru. 2016a. “Non-uniform thermal strains and stresses in energy piles.” Environ. Geotech. 3 (4): 237–252. https://doi.org/10.1680/jenge.15.00032.
Abdelaziz, S. L., and T. Y. Ozudogru. 2016b. “Selection of the design temperature change for energy piles.” Appl. Therm. Eng. 107: 1036–1045. https://doi.org/10.1016/j.applthermaleng.2016.07.067.
Alberdi-Pagola, M., S. E. Poulsen, R. L. Jensen, and S. Madsen. 2019. “Thermal design method for multiple precast energy piles.” Geothermics 78: 201–210. https://doi.org/10.1016/j.geothermics.2018.12.007.
Amatya, B. L., K. Soga, P. J. Bourne-Webb, T. Amis, and L. Laloui. 2012. “Thermo-mechanical behaviour of energy piles.” Geotechnique 62 (6): 503–519. https://doi.org/10.1680/geot.10.P.116.
Batini, N., A. F. R. Loria, P. Conti, D. Testi, W. Grassi, and L. Laloui. 2015. “Energy and geotechnical behaviour of energy piles for different design solutions.” Appl. Therm. Eng. 86: 199–213. https://doi.org/10.1016/j.applthermaleng.2015.04.050.
Bezyan, B., S. Porkhial, and A. A. Mehrizi. 2015. “3-D simulation of heat transfer rate in geothermal pile–foundation heat exchangers with spiral pipe configuration.” Appl. Therm. Eng. 87: 655–668. https://doi.org/10.1016/j.applthermaleng.2015.05.051.
Bourne-Webb, P. J., B. Amatya, K. Soga, T. Amis, C. Davidson, and P. Payne. 2009. “Energy pile test at Lambeth College, London: Geotechnical and thermodynamic aspects of pile response to heat cycles.” Geotechnique 59 (3): 237–248. https://doi.org/10.1680/geot.2009.59.3.237.
Bozis, D., K. Papakostas, and N. Kyriakis. 2011. “On the evaluation of design parameters effects on the heat transfer efficiency of energy piles.” Energy Build. 43: 1020–1029. https://doi.org/10.1016/j.enbuild.2010.12.028.
Brettmann, T., and T. Amis. 2011. “Thermal conductivity evaluation of a pile group using geothermal energy piles.” In Geo-Frontiers 2011. Advances in Geotechnical Engineering, 499–508. Reston, VA: ASCE.
Carotenuto, A., P. Marotta, N. Massarotti, A. Mauro, and G. Normino. 2017. “Energy piles for ground source heat pump applications: Comparison of heat transfer performance for different design and operating parameters.” Appl. Therm. Eng. 124: 1492–1504. https://doi.org/10.1016/j.applthermaleng.2017.06.038.
Caulk, R., E. Ghazanfari, and J. S. McCartney. 2016. “Parameterization of a calibrated geothermal energy pile model.” Geomech. Energy Environ. 5: 1–15. https://doi.org/10.1016/j.gete.2015.11.001.
Cecinato, F., and F. A. Loveridge. 2015. “Influences on the thermal efficiency of energy piles.” Energy 82: 1021–1033. https://doi.org/10.1016/j.energy.2015.02.001.
Chen, D., and J. S. McCartney. 2016. “Parameters for load transfer analysis of energy piles in uniform nonplastic soils.” Int. J. Geomech. 17 (7): 04016159. https://doi.org/10.1061/(ASCE)GM.1943-5622.0000873.
COMSOL Multiphysics®v. 5.3., n.d. Stockholm, Sweden: COMSOL AB. Accessed March 8, 2023. www.comsol.com.
Di Donna, A., and L. Laloui. 2015. “Numerical analysis of the geotechnical behaviour of energy piles.” Int. J. Numer. Anal. Methods Geomech. 39: 861–888. https://doi.org/10.1002/nag.2341.
Faizal, M., A. Bouazza, C. Haberfield, and J. S. McCartney. 2018. “Axial and radial thermal responses of a field-scale energy pile under monotonic and cyclic temperature changes.” J. Geotech. Geoenviron. Eng. 144 (10): 04018072. https://doi.org/10.1061/(ASCE)GT.1943-5606.0001952.
Gao, J., X. Zhang, J. Liu, K. S. Li, and J. Yang. 2008. “Thermal performance and ground temperature of vertical pile–foundation heat exchangers: A case study.” Appl. Therm. Eng. 28 (17–18): 2295–2304. https://doi.org/10.1016/j.applthermaleng.2008.01.013.
Hu, P., J. Zha, F. Lei, N. Zhu, and T. Wu. 2014. “A composite cylindrical model and its application in analysis of thermal response and performance for energy pile.” Energy Build. 84: 324–332.
Hu, W., W. C. Cheng, L. Wang, and Z. F. Xue. 2022. “Micro-structural characteristics deterioration of intact loess under acid and saline solutions and resultant macro-mechanical properties.” Soil Tillage Res. 220: 105382. https://doi.org/10.1016/j.still.2022.105382.
Hu, W., W. C. Cheng, S. Wen, and K. Yuan. 2021. “Revealing the enhancement and degradation mechanisms affecting the performance of carbonate precipitation in EICP process.” Front. Bioeng. Biotechnol. 9: 750258. https://doi.org/10.3389/fbioe.2021.750258.
Huang, G., X. Yang, Y. Liu, C. Zhuang, H. Zhang, and J. Lu. 2018. “A novel truncated cone helix energy pile: Modelling and investigations of thermal performance.” Energy Build. 158: 1241–1256. https://doi.org/10.1016/j.enbuild.2017.11.020.
Jahanbin, A. 2020. “Thermal performance of the vertical ground heat exchanger with a novel elliptical single U-tube.” Geothermics 86: 101804. https://doi.org/10.1016/j.geothermics.2020.101804.
Jalaluddin, A. Miyara, K. Tsubaki, S. Inoue, and K. Yoshida. 2011. “Experimental study of several types of ground heat exchanger using a steel pile foundation.” Renewable Energy 36 (2): 764–771. https://doi.org/10.1016/j.renene.2010.08.011.
Kong, L., L. Qiao, Y. Xiao, and Q. Li. 2019. “A study on heat transfer characteristics and pile group influence of enhanced heat transfer energy piles.” J. Build. Eng. 24: 100768. https://doi.org/10.1016/j.jobe.2019.100768.
Laloui, L., N. Mathieu, and V. Laurent. 2006. “Experimental and numerical investigations of the behaviour of a heat exchanger pile.” Int. J. Numer. Anal. Methods Geomech. 30: 763–781. https://doi.org/10.1002/nag.499.
Lee, C. K., and H. N. Lam. 2013. “A simplified model of energy pile for ground-source heat pump systems.” Energy 55: 838–845. https://doi.org/10.1016/j.energy.2013.03.077.
Lyu, W., H. Pu, H. Xiao, D. Hu, and Q. Ma. 2021. “Thermal performance of energy pile with deeply penetrating 1-U-shape heat exchanger.” Geothermics 91: 102023. https://doi.org/10.1016/j.geothermics.2020.102023.
Pahud, D., A. Fromentin, and M. Hubbuch. 1999. “Heat exchanger pile system for heating and cooling at Zürich airport.” IEA Heat Pump Centre Newsletter 17 (1): 15–16.
Park, H., S. R. Lee, S. Yoon, H. Shin, and D. Lee. 2012. “Case study of heat transfer behavior of helical ground heat exchanger.” Energy Build. 53: 137–144. https://doi.org/10.1016/j.enbuild.2012.06.019.
Rotta Loria, A. F., and L. Laloui. 2017. “Thermally induced group effects among energy piles.” Geotechnique 67: 374–393. https://doi.org/10.1680/jgeot.16.P.039.
Sani, A. K., R. M. Singh, C. Tsuha, and L. Cavarretta. 2019. “Pipe–pipe thermal interaction in a geothermal energy pile.” Geothermics 81: 209–223. https://doi.org/10.1016/j.geothermics.2019.05.004.
Suryatriyastuti, M. E., S. Burlon, and H. Mroueh. 2016. “On the understanding of cyclic interaction mechanisms in an energy pile group.” Int. J. Numer. Anal. Methods Geomech. 40 (1): 3–24. https://doi.org/10.1002/nag.2382.
Suryatriyastuti, M. E., H. Mroueh, and S. Burlon. 2012. “Understanding the temperature-induced mechanical behaviour of energy pile foundations.” Renewable Sustainable Energy Rev. 16 (5): 3344–3354. https://doi.org/10.1016/j.rser.2012.02.062.
Wang, B., A. Bouazza, R. M. Singh, and C. Haberfield. 2014. “Posttemperature effects on shaft capacity of a full-scale geothermal energy pile.” J. Geotech. Geoenviron. Eng. 141 (4): 04014125. https://doi.org/10.1061/(ASCE)GT.1943-5606.0001266.
Xue, Z. F., W. C. Cheng, L. Wang, and G. Y. Song. 2021. “Improvement of the shearing behaviour of loess using recycled straw fiber reinforcement.” KSCE J. Civ. Eng. 25: 3319–3335. https://doi.org/10.1007/s12205-021-2263-3.
You, S., X. Cheng, H. Guo, and Z. Yao. 2014. “In-situ experimental study of heat exchange capacity of CFG pile geothermal exchangers.” Energy Build. 79: 23–31. https://doi.org/10.1016/j.enbuild.2014.04.021.
You, T., X. Li, S. Cao, and H. Yang. 2018. “Soil thermal imbalance of ground source heat pump systems with spiral-coil energy pile groups under seepage conditions and various influential factors.” Energy Convers. Manage. 178: 123–136. https://doi.org/10.1016/j.enconman.2018.10.027.
You, T., and H. Yang. 2020. “Influences of different factors on the three-dimensional heat transfer of spiral-coil energy pile group with seepage.” Int. J. Low-Carbon Technol. 15: 458–470. https://doi.org/10.1093/ijlct/ctaa006.
Zarrella, A., C. M. De, and A. Galgaro. 2013. “Thermal performance of two types of energy foundation pile: Helical pipe and triple U-tube.” Appl. Therm. Eng. 61 (2): 301–310. https://doi.org/10.1016/j.applthermaleng.2013.08.011.
Zhang, W., H. Yang, P. Cui, L. Lu, N. Diao, and Z. Fang. 2015. “Study on spiral source models revealing groundwater transfusion effects on pile foundation ground heat exchangers.” Int. J. Heat Mass Transf. 84: 119–129. https://doi.org/10.1016/j.ijheatmasstransfer.2014.12.036.
Zhang, W., H. Yang, L. Lu, and Z. Fang. 2012. “Investigation on heat transfer around buried coils of pile foundation heat exchangers for ground-coupled heat pump applications.” Int. J. Heat Mass Transf. 55 (21–22): 6023–6031. https://doi.org/10.1016/j.ijheatmasstransfer.2012.06.013.
Zhao, Q., F. Liu, C. Liu, M. Tian, and B. Chen. 2017. “Influence of spiral pitch on the thermal behaviors of energy piles with spiral-tube heat exchanger.” Appl. Therm. Eng. 125: 1280–1290. https://doi.org/10.1016/j.applthermaleng.2017.07.099.
Information & Authors
Information
Published In
Copyright
© 2023 American Society of Civil Engineers.
History
Received: Oct 13, 2022
Accepted: Jun 25, 2023
Published online: Oct 4, 2023
Published in print: Dec 1, 2023
Discussion open until: Mar 4, 2024
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.