### Numerical Investigation of the Physical Properties Effect on the Thermal Performance of a Vertical Geothermal Heat Exchanger

#### Abstract

Low-temperature geothermal energy is a promising technique for heating and cooling residential and commercial premises, especially since it is one of the green energy solutions that respect the environment. The principle of this technique is based on thermal exchange between the heat pump and the basement using a vertically buried heat exchanger. This is usually made of a U-shaped tube inserted vertically in a borehole made in the ground and filled with a filler material. The purpose of the present study is to vary the different construction materials of the U-tube, the filling material and the soil, in order to obtain the most energy-efficient parameters. The evolution of temperature and heat flux as a function of time has been highlighted for different combinations. Knowing that an experimental study requires a considerable monetary fund, the present model has been validated using previously literature results. Recommendations on the choice of different materials of the geothermal heat exchanger are proclaimed at the end of this work.

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B. Sanner, C. Karytsas, D. Mendrinos, L. Rybach, “Current status of ground source heat pumps and underground thermal energy storage in Europe”, Geothermics, Vol. 32, Vol. 4-6, pp. 579-588, 2003

J. W. Lund, D. H. Freeston, T. L. Boyd, “Direct utilization of geothermal energy 2010 worldwide review”, Geothermics, Vol. 40, No. 3, pp. 159-180, 2011

T. Bandos, A. E. Montero Reguera, P. J. Fernandez de Cordoba Castella, J. F. Urchueguía Schölzel, “Urchueguia, Improving parameter estimates obtained from thermal response tests: effect of ambient air temperature variations”, Geothermics, Vol. 40, No. 2, pp. 136-143, 2011

A. D. Chiasson, Advances in modeling of ground-source heat pump systems, MSc Thesis, Oklahoma State University, 1999

A. M. Omer, “Ground-source heat pumps systems and applications”, Renewable & Sustainable Energy Reviews, Vol. 12, No. 2, pp. 344-371, 2008

C. Yavuzturk, J. D. Spitler, S. J. Rees, “A transient two-dimensional finite volume model for the simulation of vertical U-tube ground heat exchangers”, ASHRAE Transactions, Vol. 105, No. 2, pp. 465-474, 1999

L. R. Ingersoll, “Theory of Earth Heat Exchangers for the Heat Pump, Heat Conduction”, American Society of Heating and Ventilating Engineers, Journal section, Heating, Piping, and Air Conditioning, 1950

H. S. Carslaw, J. C. Jaeger, Conduction of Heat in Solids, Oxford University Press, 1959

P. Eskilson, Thermal analysis of heat extraction boreholes, PhD Thesis, University of Lund, 1987

S. P. Rottmayer, W. A. Bechman, J. W. Mitchell “Simulation of a single vertical U-tube ground heat exchanger in an infinite medium”, ASHRAE Transactions, Vol. 103, pp. 651–659, 1997

N. K. Muraya, D. L. O’Neal, W. M. Heffington, “Thermal interference of adjacent legs in vertical U-tube heat exchanger for a ground-coupled heat pump”, ASHRAE Transactions,Vol. 102, No. 2, pp. 12-21, 1996

J. A. Shonder, J. V. Beck, “Determining effective soil formation thermal properties from field data using parameter estimation technique”, ASHRAE Transactions, Vol. 105, pp. 458-466, 1999

C. K. Lee, H. N. Lam, “Computer simulation of borehole ground heat exchanger for geothermal heat pump systems”, Renewable Energy, Vol. 33, No. 6, pp. 1286-1296, 2008

D. Marcotte, P. Pasquier, “On the estimation of thermal resistance in borehole thermal conductivity test”, Renewable Energy, Vol. 33, No. 11, pp. 2407-2415, 2008

Z. J. Li, M. Y. Zheng, “Development of a numerical model for the simulation of vertical U-tube ground heat exchangers”, Applied Thermal Engineering, Vol. 29, No. 5-6, pp. 920-924, 2009

C. Yavuzturk, J. D. Spitler, “A short time step response factor model for vertical ground loop heat exchangers”, ASHRAE Transactions, Vol. 105, No. 2, pp. 475-485, 1999

J. Claesson, S. Javed, “An analytical method to calculate borehole fluid temperatures for time-scales from minutes to decades”, ASHRAE Transactions,Vol. 117, No. 2, pp. 279-288, 2011

L. Lamarche, S. Kajl, B. Beauchamp, “A review of methods to evaluate borehole thermal resistances in geothermal heat-pump systems”, Geothermics, Vol. 39, No. 2, pp. 187-200, 2010

D. Marcotte, P. Pasquier, F. Sherif, M. Bernier, “The importance of axial effects for borehole design of geothermal heat-pump systems”, Renewable Energy, Vol. 35, No. 4, pp. 763-770, 2010

B. Bouhacina, R. Saim, H. Benzenine, H. F. Oztop, “Analysis of thermal and dynamic comportment of a geothermal vertical U-tube heat exchanger”, Energy and Buildings, Vol. 58, pp. 37-43, 2013

L. Pu, D. Qi, K. Li, H. Tan, Y. Li, “Simulation study on the thermal performance of vertical U-tube heat exchangers for ground source heat pump system”, Applied Thermal Engineering, Vol. 79, pp. 202-213, 2015

C. Zhang, P. Chen, Y. Liu, S. Sun, D. Peng, “An improved evaluation method for thermal performance of borehole heat exchanger”, Renewable Energy, Vol. 77, pp. 142-151, 2015

W. Fujun (Ed.), The Dynamics Analysis of the Computational Fluid, Tsinghua University Press, 2004

S. V. Patankar, Numerical Heat Transfer and Fluid Flow, Hemisphere, 1980

P. Eskilson, J. Claesson, “Simulation model for thermally interacting heat extraction boreholes”, Numerical Heat Transfer, Vol. 13, No. 2, pp. 149-165, 1988

C. K. Lee, H. N. Lam, “Computer simulation of borehole ground heat exchangers for geothermal heat pump systems”, Renewable Energy, Vol. 33, pp. 1289-1296, 2008

H. Y. Zeng, N. R. Diao, Z. H. Fang, “A finite line-source model for boreholes in geothermal heat exchangers”, Heat Transfer - Asian Research, Vol. 31, No. 7, pp. 558-567, 2002

E. J. Kim, J. J. Roux, G. Rusaouen, F. Kuznik, “Numerical modeling of geothermal vertical heat exchangers for the short time analysis using the state model size reduction technique”, Applied Thermal Engineering, Vol. 30, No. 6-7, pp. 706-714, 2010

W. Yang, M. Shi, G. Liu, Z. Chen, “A two-region simulation model of vertical U-tube ground heat exchanger and its experimental verification”, Applied Energy, Vol. 86, No. 10, pp. 2005-2012, 2009

D. Fadla, Manuel de maillage sous Gambit et de simulation sous Fluent applications, Laboratoire d’énergétique et de mécanique de fluides interne ENSAM, CER de Paris, 2007

Jalaluddin, A. Miyara . “Thermal performance investigation of several types of vertical ground heat exchangers with different operation mode”, Applied Thermal Engineering, Vol. 33-34, pp. 167-174, 2012

R. Al-Khoury, S. Focaccia, “A spectral model for transient heat flow in a double U-tube geothermal heat pump system”, Renewable Energy, Vol. 85, pp. 195-205, 2016

T. Y. Ozudogru, C. G. Olgun, A. Senol, “3D numerical modeling of vertical geothermal heat exchangers”, Geothermics, Vol. 51, pp. 312-324, 2014

T. Y. Ozudogru, O. Ghasemi-Fare, G. Olgun, P. Basu, “Numerical modeling of vertical geothermal heat exchanger using finite difference and finite element techniques”, Geotechnical and Geological Engineering, Vol. 33, No. 2, pp. 291-306, 2015

B. Bezyan, S. Porkhial, A. Aboui Mehrizi, “3-D simulation of heat transfer rate in geothermal pile-foundation heat exchangers with spiral pipe configuration”, Applied Thermal Engineering, Vol. 87, pp. 655-668, 2015

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