Long-Term Performance Investigation on Seasonal Heat Storage of U-Type Backfill Heat Exchangers in Mine Stopes Coupling a Solar-Assisted Heat Pump

ZHANG Bo, WU Zhiqiang, LIU Lang, HUAN Chao, ZHAO Yujiao, WANG Mei, WANG Xueli, ZHANG Xiaoyan

Journal of Thermal Science ›› 2025, Vol. 34 ›› Issue (3) : 1091-1116.

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Journal of Thermal Science ›› 2025, Vol. 34 ›› Issue (3) : 1091-1116. DOI: 10.1007/s11630-025-2135-0  CSTR: 32141.14.JTS-025-2135-0

Long-Term Performance Investigation on Seasonal Heat Storage of U-Type Backfill Heat Exchangers in Mine Stopes Coupling a Solar-Assisted Heat Pump

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Abstract

The mined-out areas formed by ore extraction have promoted the development of seasonal energy storage technology in underground spaces. Currently, most studies on the heat storage/release performance of backfills with embedded heat exchange pipes have idealized the operating conditions, such as constant fluid inlet temperature and flow rate. However, actual operating conditions are influenced by many factors like weather conditions, surface equipment, and heat load fluctuations, making them unstable. Therefore, this paper constructs a solar-assisted heat pump coupled mine backfill body heat storage system (SAHP-MBBHSs) based on TRNSYS simulation software and verifies the accuracy of the backfill heat exchangers (BFHEs) model through experiments. Considering the influence of various external factors on the operating conditions, we investigated the long-term seasonal heat storage/release performance of the BFHEs, focusing on the effects of solar collector area, U-tube spacing, thermal conductivity of backfill materials, and heat storage start/stop time. The results show that reducing the U-tube spacing increases the fluctuation amplitude of the average temperature of the backfill body, with the maximum average fluctuation amplitude difference reaching 16.6°C between the 11th and 15th years. Delaying the onset of thermal storage reduces the storage effectiveness of the U-BFHEs, while increasing the heat release effectiveness. During the thermal storage/release interval, heat loss to the surrounding rock does not exceed 4.7%, with the minimal overall impact. The thermal conductivity of the backfill body has the greatest effect on the heat transfer effectiveness of U-BFHEs, increasing from 1 W·m–1·K–1 to 2 W·m–1·K–1 resulting in respective increases of 58.8% and 39.2% in the heat transfer effectiveness during the 15th year of thermal storage/release. The total heat storage-release effectiveness of the U-BFHEs does not exceed 43.7%, indicating significant room for improvement. Utilizing seasonal thermal storage in the backfill body can effectively enhance the heating performance of SAHP-MBBHSs, with the maximum average APF and HSPF values reaching 3.85 and 5.43, respectively, during the 11th–15th years of operation, maintaining high efficiency even after long-term operation.

Key words

U-type backfill heat exchangers / seasonal heat storage / TRNSYS simulation / solar-assisted heat pump system

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ZHANG Bo , WU Zhiqiang , LIU Lang , HUAN Chao , ZHAO Yujiao , WANG Mei , WANG Xueli , ZHANG Xiaoyan. Long-Term Performance Investigation on Seasonal Heat Storage of U-Type Backfill Heat Exchangers in Mine Stopes Coupling a Solar-Assisted Heat Pump[J]. Journal of Thermal Science, 2025, 34(3): 1091-1116 https://doi.org/10.1007/s11630-025-2135-0

References

[1] Yuan J., Luo X., Regional energy security performance evaluation in China using MTGS and SPA-TOPSIS. Science of the Total Environment, 2019, 696: 133817.
[2] Musa S.D., Tang Z., Ibrahim A.O., et al., China’s energy status: A critical look at fossils and renewable options. Renewable and Sustainable Energy Reviews, 2018, 81: 2281–2290.
[3] Prăvălie R., Bandoc G., Nuclear energy: Between global electricity demand, worldwide decarbonisation imperativeness, and planetary environmental implications. Journal of Environmental Management, 2018, 209: 81–92.
[4] Yang Z., Zhan J., Examining the multiple impacts of renewable energy development on redefined energy security in China: A panel quantile regression approach. Renewable Energy, 2024, 221: 119778.
[5] Yuan L., Zhang T., Zhang Q., et al., Construction of green, low-carbon and multi-energy complementary system for abandoned mines under global carbon neutrality. China Coal Society, 2022, 47(06): 2131–2139. (in Chinese)
[6] Fang Z., Liu L., Zhang X., et al., Carbonation curing of modified magnesium-coal based solid waste backfill material for CO2 sequestration. Process Safety and Environmental Protection, 2023, 180: 778–788.
[7] Yang T., Liu W., Kramer G.J., et al., Seasonal thermal energy storage: A techno-economic literature review. Renewable & Sustainable Energy Reviews, 2021, 139: 110732.
[8] Su C., Madani H., Palm B., Heating solutions for residential buildings in China: Current status and future outlook. Energy Conversion and Management, 2018, 177: 493–510.
[9] Carnie J.-T., Hardalupas Y., Sergis A., Decarbonising building heating and cooling: Designing a novel, inter-seasonal latent heat storage system. Renewable and Sustainable Energy Reviews, 2024, 189: 113897.
[10] Guo J., Li R., Cai P., et al., Risk in solar energy: Spatio-temporal instability and extreme low-light events in China. Applied Energy, 2024, 359: 122749.
[11] Jiang H., Lu N., Yao L., et al., Impact of climate changes on the stability of solar energy: Evidence from observations and reanalysis. Renewable Energy, 2023, 208: 726–736.
[12] Zhan R., Zhang B., Liu L., et al., Strength and damage constitutive model of backfill body after high temperature treatment. Engineering Fracture Mechanics, 2025, 314: 110686.
[13] Menéndez J., Ordóñez A., Álvarez R., et al., Energy from closed mines: Underground energy storage and geothermal applications. Renewable and Sustainable Energy Reviews, 2019, 108: 498–512.
[14] Honarmand H.A., Rashid S.M., A sustainable framework for long-term planning of the smart energy hub in the presence of renewable energy sources, energy storage systems and demand response program. Journal of Energy Storage, 2022, 52: 105009.
[15] Wu F., Liu Y., Gao R., Challenges and opportunities of energy storage technology in abandoned coal mines: A systematic review. Journal of Energy Storage, 2024, 83: 110613.
[16] Sun B., Fan B., Zhang Y., et al., Investment decisions and strategies of China’s energy storage technology under policy uncertainty: A real options approach. Energy, 2023, 278: 127905.
[17] Sadeghi H., Jalali R., Singh R.M., A review of borehole thermal energy storage and its integration into district heating systems. Renewable and Sustainable Energy Reviews, 2024, 192: 114236.
[18] Ahmadfard M., Bernier M., Simulation of borehole thermal energy storage (BTES) systems using simplified methods. Journal of Energy Storage, 2023, 73: 109240.
[19] Zhou W., Li R., Chen Y., et al., Numerical simulation of mid-deep buried casing heat exchanger and its heating system application. Journal of Thermal Science, 2023, 32(4): 1445–1454.
[20] Yang W., Zhang Y., Wang F., et al., Experimental and numerical investigations on operation characteristics of seasonal borehole underground thermal energy storage. Renewable Energy, 2023, 217: 119365.
[21] Mesquita L., Mcclenahan D., Thornton J., et al., Drake landing solar community: 10 years of operation. ISES Solar World Congress 2017, pp. 1–12. 
DOI: 10.18086/swc.2017.06.09.
[22] Sun T., Yang L., Jin L., et al., A novel solar-assisted ground-source heat pump (SAGSHP) with seasonal heat-storage and heat cascade utilization: Field test and performance analysis. Solar Energy, 2020, 201: 362–372.
[23] Guo F., Yang X., Long-term performance simulation and sensitivity analysis of a large-scale seasonal borehole thermal energy storage system for industrial waste heat and solar energy. Energy and Buildings, 2021, 236: 110768.
[24] Zhou X., Xu Y., Zhang X., et al., Large scale underground seasonal thermal energy storage in China. Journal of Energy Storage, 2021, 33: 102026.
[25] Renaldi R., Friedrich D., Techno-economic analysis of a solar district heating system with seasonal thermal storage in the UK. Applied Energy, 2019, 236: 388–400.
[26] Pokhrel S., Amiri L., Poncet S., et al., Reduced order 1+3D numerical model for evaluating the performance of solar borehole thermal energy storage systems. Journal of Energy Storage, 2023, 66: 107503.
[27] Ghoreishi-Madiseh S.A., Hassani F., Abbasy F., Numerical and experimental study of geothermal heat extraction from backfilled mine stopes. Applied Thermal Engineering, 2015, 90: 1119–1130.
[28] Li B., Zhang J., Ghoreishi-Madiseh S.A., et al., Energy performance of seasonal thermal energy storage in underground backfilled stopes of coal mines from China. Journal of Cleaner Production, 2020, 275: 122647.
[29] Zhan R., Zhang B., Liu L., et al., An improved equivalent heat capacity method to simulate and optimize latent thermal energy storage units. International Journal of Heat and Mass Transfer, 2024, 235: 126135.
[30] Zhang X., Xu M., Liu L., et al., Heat storage/heat release of phase-change filling body with casing heat exchanger for extracting geothermal energy. Journal of Thermal Science, 2023, 32(3): 1171–1189.
[31] Zhang X., Wen D., Zhao Y., et al., Thermal-mechanical properties and heat transfer process of heat storage/ energy storage backfill body in mine. China Coal Society, 2021, 46(10): 3158–3171. (in Chinese)
[32] Zhao Y., Liu L., Wen D., et al., Recycling waste material for backfill coupled heat exchanger systems in underground stopes of mines. Energy and Buildings, 2022, 256: 111703.
[33] Zhang X., Zhao M., Liu L., et al., Numerical simulation on heat storage performance of backfill body based on tube-in-tube heat exchanger. Construction and Building Materials, 2020, 265: 120340.
[34] Ning P., Ju F., Xiao M., et al., Study on the thermal - mechanical properties and heat transfer characteristics of heat storage functional backfill body. Geothermics, 2023, 109: 102654.
[35] Li B., Zhang J., Yan H., et al., Numerical investigation into the effects of geologic layering on energy performances of thermal energy storage in underground mines. Geothermics, 2022, 102: 102403.
[36] Liu H., Rodriguez-Dono A., Zhang J., et al., A new method for exploiting mine geothermal energy by using functional cemented paste backfill material for phase change heat storage: Design and experimental study. Journal of Energy Storage, 2022, 54: 105292.
[37] Yin Y., Qiao L., Li Q., et al., Mechanical and thermo-physical properties of heat and energy storage backfill based on MicroPCMs. Journal of Building Engineering, 2024, 83: 108451.
[38] Wang H., Zhang D., Qian Z., et al., A novel paraffin/graphite PCM backfill for PHC energy pile: Numerical and experimental analysis on thermal performance. Applied Thermal Engineering, 2025, 258: 124656.
[39] Liu Y., Min L., Zhang S., et al., Study on the thermal-mechanical properties and heat transfer characteristics of low leakage heat storage functional backfill body. Journal of Energy Storage, 2024, 94: 112257.
[40] Yin Y., Qiao L., Li Q., et al., Thermodynamic performance of SiC-enhanced MicroPCM backfill based on response surface methodology. Case Studies in Construction Materials, 2024, 20: e03345.
[41] Guardia C., Barluenga G., Palomar I., et al., Thermal enhanced cement-lime mortars with phase change materials (PCM), lightweight aggregate and cellulose fibers. Construction and Building Materials, 2019, 221: 586–594.
[42] Zhao Y., Liu L., Wen D., et al., Experimental study of horizontal ground heat exchangers embedded in the backfilled mine stopes. Geothermics, 2022, 100: 102344.
[43] Zhang B., Zhan R., Liu L., et al., A comparative analysis of the performance of backfill heat exchangers in deep mine geological environments. Applied Thermal Engineering, 2024, 239: 122092.
[44] Zhang B., Yang Z., Liu L., et al., Thermal interference of backfill heat exchangers in heat storage/release processes in deep mines. China Coal Society, 2023, 48(03): 1155–1168. (in Chinese)
[45] Zheng X., Tang Z., Wang Y., et al., Performance of the air source heat pump assisted solar heating system combined with PCM floor. Applied Thermal Engineering, 2024, 239: 122115.
[46] High temperature water source heat pump. http://file.co188.com/ebook/openEBook2.action?bookId=1146291850231&pageNo=0,2007 (accessed on October 13, 2007).
[47] Hellström G., Ground heat storage: thermal analyses of duct storage systems. Lund University, Lund, England, 1991.
[48] Zhang C., Song W., Liu Y., et al., Effect of vertical ground temperature distribution on parameter estimation of in-situ thermal response test with unstable heat rate. Renewable Energy, 2019, 136: 264–274.
[49] Li Y., Bi Y., Lin Y., et al., Analysis of the soil heat balance of a solar-ground source absorption heat pump with the soil-based energy storage in the transition season. Energy, 2023, 264: 126394.
[50] Li P., Guo F., Yang X., An inversion method to estimate the thermal properties of heterogeneous soil for a large-scale borehole thermal energy storage system. Energy and Buildings, 2022, 263: 112045.
[51] Wang C., Guo F., Zhu Y., et al., Design and optimization of large-scale seasonal borehole thermal energy storage system for solar energy. Acta Energiae Solaris Sinica, 2021, 42(04): 320–327. (in Chinese)
[52] Beier R.A., Smith M.D., Spitler J.D., Reference data sets for vertical borehole ground heat exchanger models and thermal response test analysis. Geothermics, 2011, 40(1): 79–85.
[53] Li M., Lai A.C.K., Analytical model for short-time responses of ground heat exchangers with U-shaped tubes: Model development and validation. Applied Energy, 2013, 104: 510–516.
[54] Wu G., Ding G., Ren T., A fast prediction method for maximum APF of heat pump type air conditioners based on a single group of experimental data. International Journal of Refrigeration, 2020, 115: 126–138.
[55] Sun C., Ju X., Hao W., et al., Research on multi-objective optimization of control strategies and equipment parameters for a combined heating system of geothermal and solar energy in cold and arid regions based on TRNSYS. Case Studies in Thermal Engineering, 2023, 50: 103441.
[56] Tao W., Heat transfer, Fifth ed., Higher Education Press, Beijing, 2019.
[57] Liang G., Research on disturbance assessment and protection methods for groundwater environment during Sijiaying iron mining development. China University of Ming and Technology, Beijing, China, 2012.
[58] Yang Z., Zhai S., Gao Q., et al., Stability analysis of large-scale stope using stage subsequent filling mining method in Sijiaying iron mine. Journal of Rock Mechanics and Geotechnical Engineering, 2015, 7(01): 87–94.
[59] Zhang R., Xie Z., Wu J., et al., The distribution of heat flow values in Tangshan and its surroundings. Seismology and Geology, 1982, 4(04): 57–67. (in Chinese)

Funding

This research was supported by National Natural Science Foundation of China (Nos. 52274063, 52104148, 52004207, 52074212); Natural Science Basic Research Plan of Shaanxi Province of China (No. 2022JM-173).

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Science Press, Institute of Engineering Thermophysics, CAS and Springer-Verlag GmbH Germany, part of Springer Nature 2025
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