Numerical and experimental study of heat transfer from a cylindrical pipe in greenhouse soil

THE RELEVANCE. Heating of greenhouse spaces during the winter season has been and remains one of the most energy-intensive cost items in greenhouse operation. The integration of renewable energy sources with high-temperature thermal storage systems helps to mitigate the imbalance between energy generation and consumption; however, this approach requires validated ground heat transfer models for the reliable design of subsurface heating systems. THE PURPOSE. To perform numerical modeling and experimental validation of heat transfer from a buried pipe, considering soil moisture content, for subsequent application in localized greenhouse soil heating systems. METHODS. Two series of laboratory experiments were conducted using dried (moisture < 10%) and moistened (moisture ≈ 45%) loamy soil. Soil temperature was monitored using 20 DS18B20 sensors and a UTi260B thermal imager. A two-dimensional computational domain was developed, and a mesh grid was constructed. Transient numerical simulations were performed in ANSYS Fluent. The unsteady-state heat conduction equation was solved using the finite volume method, incorporating actual thermophysical properties of the soil. RESULTS. The average relative deviation between simulated and experimental temperatures was below 6% for dried soil and around 4% for moistened soil, confirming model accuracy. Moistened soil exhibited 15-20% faster heating and achieved 2-3 °C higher temperatures in the 2-4 cm depth range due to reduced thermal resistance in the saturated pore structure. Thermographic imaging showed that the effective heating width of a single pipe was limited to 1-2 cm, indicating the need for a pipe bundle or coil arrangement to ensure uniform heating of the root zone. CONCLUSION. The validated model serves as a tool for optimizing the geometry of subsurface pipe layouts based on soil moisture content.

1. Soussi A., Zero E., Ouammi A., et al. Smart greenhouse farming: a review towards near zero energy consumption. Discov Cities. 2025;2:55. doi: 10.1007/s44327-025-00096-w.

2. Teplichnaya otrasl' – 2025. APK-news.ru: site of the agro-industrial complex news of the South and the Caucasus; 28 Apr 2025. Sochi; 2025. Available at: https://www.apk-news.ru/teplichnaya-otrasl-2025/. Accessed: 15 Jul 2025. (In Russ.).

3. Sun W., Wei X., Zhou B., Lu C., Guo W. Greenhouse heating by energy transfer between greenhouses: System design and implementation. Applied Energy. 2022;325:119815. doi: 10.1016/j.apenergy.2022.119815.

4. Sokovikova A.V. Improving the energy efficiency of greenhouse heating and ventilation systems using logic controllers. Vestn. Izhevsk. State Agric. Acad. 2009;3–4(20–21):48–49. (In Russ.)

5. Boyacı S., Kocięcka J., Jagosz B., Atılgan A. Energy efficiency in greenhouses and comparison of energy sources used for heating. Energies. 2025;18(3):724. doi: 10.3390/en18030724.

6. Ahamed M.S., Guo H., Tanino K. Energy saving techniques for reducing the heating cost of conventional greenhouses. Biosyst. Eng. 2019;178:9–33. doi: 10.1016/j.biosystemseng.2018.10.017.

7. Cuce E., Harjunowibowo D., Cuce P.M. Energy use in greenhouses in the EU: A review recommending energy-efficiency measures and renewable-energy adoption. Applied Sciences. 2022;12(10):5150. doi: 10.3390/app12105150.

8. Seo Y., Seo U.-J. Ground source heat pump (GSHP) systems for horticulture greenhouses adjacent to highway interchanges: A case study in South Korea // Renewable and Sustainable Energy Reviews. 2021;135:110194. doi: 10.1016/j.rser.2020.110194.

9. Prieto J., Ajnannadhif R.M., Fernández-del-Olmo P. Integration of a heating and cooling system driven by solar thermal energy and biomass for a greenhouse in Mediterranean climates. Applied Thermal Engineering. 2023;221:119928. doi: 10.1016/j.applthermaleng.2022.119928.

10. Huang T., Li H., Zhang G., Xu F. Experimental study on biomass heating system in the greenhouse: A case study in Xiangtan, China. Sustainability. 2020;12(14):5673. doi: 10.3390/su12145673.

11. Ghaderi M., Reddick C., Sorin M. A systematic heat recovery approach for designing integrated heating, cooling and ventilation systems for greenhouses. Energies. 2023;16(14):5493. doi: 10.3390/en16145493.

12. Nishad S., Krupa I. Phase change materials for thermal energy storage applications in greenhouses: A review. Sustainable Energy Technologies and Assessments. 2022;52:102241. doi: 10.1016/j.seta.2022.102241.

13. Tahery D., Roshandel R., Avami A. An integrated dynamic model for evaluating the influence of ground-to-air heat transfer system on heating, cooling and CO₂ supply in greenhouses. Renewable Energy. 2021;173:42–56. doi: 10.1016/j.renene.2021.03.120.

14. Adesanya MA, Rabiu A, Ogunlowo QO, et al. Experimental evaluation of hybrid renewable and thermal energy storage systems for a net-zero energy greenhouse: A case study of Yeoju-Si. Energies. 2025;18(10):2635. doi: 10.3390/en18102635.

15. Zhang X, Li Y, Wang P. Thermo-economic analysis of a low-cost greenhouse thermal solar plant with seasonal energy storage. Energy Convers. Manag. 2023;276:116626. doi: 10.1016/j.enconman.2023.116626.

16. van der Stelt A, Rouwette N, Bloemendal J. Aquifer thermal energy storage for low-carbon greenhouse heating in the Netherlands. Applied Energy. 2024;331:120545. doi: 10.1016/j.apenergy.2023.120545.

17. Fan M, Ding Y, Liang X. Molten salts tanks thermal energy storage: aspects to consider for renewable integration. Energies. 2022;17(1):22. doi: 10.3390/en17010022.

18. Reimann T, Neldner K. A perspective on high-temperature heat storage using liquid metal as heat-transfer fluid. Energy Storage. 2023;3:e530. doi: 10.1002/est2.530.

19. Li S, Chen H, Wang J. Modeling and implementation of multilayer insulation for small-scale high-temperature thermal energy storage tank. Int J Heat Mass Transf. 2024;214:124567. doi: 10.1016/j.ijheatmasstransfer.2024.124567.

20. Smolentsev N.I., Kondrin S.A. Superconducting electrokinetic energy storage for local electric networks. Proceedings of the higher educational institutions. ENERGY SECTOR PROBLEMS. 2017;19(3– 4):53–60. (In Russ.)

21. Serdechnyi D.V., Tomashevsky Yu.B. Operational features of a multi-element lithium-ion battery-based energy storage system. Proceedings of the higher educational institutions. ENERGY SECTOR PROBLEMS. 2017;19(9–10):140–145. (In Russ.)

22. Fedotov A.I., Fedotov E.A., Abdullazyanov A.F. Use of electrochemical energy storage in autonomous power supply systems to reduce fuel consumption of power plants. Proceedings of the higher educational institutions. ENERGY SECTOR PROBLEMS. 2021;23(1):3–17. doi: 10.30724/1998-9903-2021-23-1-3-17. (In Russ.)

23. Smolentsev N.I., Bondareva V.Yu. Results of development and experimental research of the energy storage complex with SPENE-1 energy storage. Proceedings of the higher educational institutions. ENERGY SECTOR PROBLEMS. 2024;26(6):121–131. doi: 10.30724/1998-9903-2024-26-6-121-131. (In Russ.)

24. Chadaev A.N., Dmitriev A.V., Zinurov V.E., et al. Algorithm for calculating a multilayer thermal insulation system of a thermal energy storage unit with a high-temperature working fluid. Proceedings of the higher educational institutions. ENERGY SECTOR PROBLEMS. 2024;26(6):166–179. doi: 10.30724/1998-9903-2024-26-6-166-179. (In Russ.)

25. Chadaev A.N., Dmitriev A.V., Zinurov V.E., et al. Evaluation of energy transfer in a thermal energy storage unit with high-temperature working fluid during discharge. Bull. South Ural State Univ. Ser. Power Eng. 2024;24(4):73–85. doi: 10.14529/power240409. (In Russ.)

26. Dmitriev A.V., Zinurov V.E., Utkin M.O., et al. Numerical modeling of thermal energy storage heating for greenhouse farming. Vestn. Kazan State Agrar. Univ. 2025;20(1(77)):47–53. doi: 10.12737/2073-0462-2025-1-47-53. (In Russ.)

27. Li S., Sun T., Du Y., et al. Influence of moisture on heat transfer of ground heat exchangers in unsaturated soils. Renewable Energy. 2022;193:1177–1185.

28. Liu Z., Du Y., Song C., et al. Effect of soil moisture content on thermal performance of ground source heat exchangers: An electromagnetism topology-based analysis. Energy Reports. 2023;10:3914–3928.

29. Bazgaou A., Fatnassi H., Bouharroud R., et al. CFD modeling of the microclimate in a greenhouse using a rock bed thermal storage heating system. Horticulturae. 2023;9:183. doi: 10.3390/horticulturae9020183.

30. Badretdinova G.R., Kalimullin I.R., Zinurov V.E., et al. Evaluation of turbulence models for external flow around a heated pipe. Proceedings of the higher educational institutions. ENERGY SECTOR PROBLEMS. 2023;25(2):176–186. doi: 10.30724/1998-9903-2023-25-2-176-186. (In Russ.)