Numerical analysis of baffles on geothermal energy in a U-shaped heat exchanger

Lamia Benahmed, Khaled Aliane, Brahim Rostane, Said Abboudi

Abstract


This work focuses on geothermal energy recovery using a vertical geothermal heat exchanger coupled with a heat pump for heating applications. The primary objective of this study is to conduct a 3D numerical simulation to evaluate the effects of baffles on the thermal performance of a U-shaped heat exchanger. These baffles, designed to alter flow characteristics, were implemented to enhance heat transfer and optimize overall system efficiency. The mathematical model is based on the governing equations of fluid mechanics and thermodynamics, solved using the finite volume method in the Ansys CFX software. Various baffle configurations were investigated, focusing on their placement (on the inlet and outlet tube), geometry, and the use of perforations with decreasing diameters. Simulations were conducted for a Reynolds number of Re=3600, capturing the flow behavior under specific conditions. The analysis revealed that the optimal configuration, involving baffles strategically placed on the outlet tube with decreasing perforation diameters, significantly improved thermal performance. These findings highlight the potential for designing more efficient heat exchangers in geothermal systems, paving the way for advancements in sustainable energy solutions.


Keywords


Geothermal energy, Heat transfer, U-shaped exchanger, Baffles, Turbulence model, ANSYS -CFX

Full Text:

PDF

References


J. Goldemberg et al., “World energy assessment.”.

Thermal Use of the Underground; Part 1: Fundamentals, Approvals, Environmental Aspects. VDI-Richtlinien VDI 4640/I Verein Deutscher Ingenieure (VDI) in Düsseldorf, 2000.

E. Abu-Nada et al., “Modeling of a geothermal standing column well,” Int J Energy Res, vol. 32, no. 4, 2008, doi: 10.1002/er.1355.

A. Nguyen, P. Pasquier, and D. Marcotte, “Thermal resistance and capacity model for standing column wells operating under a bleed control,” Renew Energy, vol. 76, 2015, doi: 10.1016/j.renene.2014.11.080.

Dong Youp Kwak, Duhee Park, J. H. Chang, S. M. Na, and S. Park, “Parametric Study for Evaluation of Design Parameters of Standing Column Well,” Parametric Study for Evaluation of Design Parameters of Standing Column Well. In ProCeeding of World Geothermal COngreSS., 2010.

D. Kim, M. Lim, B. Yu, and C. Lee, “Smart heating and cooling heat pump system by standing column well and cross-mixing balancing well heat exchangers,” Applied Sciences (Switzerland), vol. 10, no. 21, 2020, doi: 10.3390/app10217643.

B. M. Ng, “Numerical Modeling of Multiple Standing Column Wells Applied to Geothermal Heating and Cooling in UK Buildings,” Ph.D. Thesis, University of Northumbria at Newcastle., 2011. [Online]. Available: https://nrl.northumbria.ac.uk/id/eprint/7265/

D. Pahud and B. Matthey, “Comparison of the thermal performance of double U-pipe borehole heat exchangers measured in situ,” Energy Build, vol. 33, no. 5, pp. 503–507, May 2001, doi: 10.1016/S0378-7788(00)00106-7.

J. A. Shonder and J. V. Beck, “Field test of a new method for determining soil formation thermal conductivity and borehole resistance,” in ASHRAE Transactions, 2000.

M. Inalli and H. Esen, “Experimental thermal performance evaluation of a horizontal ground-source heat pump system,” Appl Therm Eng, vol. 24, no. 14–15, 2004, doi: 10.1016/j.applthermaleng.2004.01.005.

M. Sheikholeslami, M. M. Rashidi, T. Hayat, and D. D. Ganji, “Free convection of magnetic nanofluid considering MFD viscosity effect,” J Mol Liq, vol. 218, 2016, doi: 10.1016/j.molliq.2016.02.093.

M. Sheikholeslami and D. D. Ganji, “Influence of electric field on Fe3O4- water nanofluid radiative and convective heat transfer in a permeable enclosure,” J Mol Liq, vol. 250, 2018, doi: 10.1016/j.molliq.2017.12.028.

M. Sheikholeslami, “Numerical simulation for solidification in a LHTESS by means of nano-enhanced PCM,” J Taiwan Inst Chem Eng, vol. 86, 2018, doi: 10.1016/j.jtice.2018.03.013.

G. Florides and S. Kalogirou, “Ground heat exchangers-A review of systems, models and applications,” 2007. doi: 10.1016/j.renene.2006.12.014.

H. Esen, M. Inalli, and M. Esen, “Numerical and experimental analysis of a horizontal ground-coupled heat pump system,” Build Environ, vol. 42, no. 3, 2007, doi: 10.1016/j.buildenv.2005.11.027.

M. Sheikholeslami, M. Jafaryar, D. D. Ganji, and Z. Li, “Exergy loss analysis for nanofluid forced convection heat transfer in a pipe with modified turbulators,” J Mol Liq, vol. 262, 2018, doi: 10.1016/j.molliq.2018.04.077.

K. S. Lee, “Modeling on the cyclic operation of standing column wells under regional groundwater flow,” Journal of Hydrodynamics, vol. 23, no. 3, 2011, doi: 10.1016/S1001-6058(10)60116-3.

E. Abu-Nada et al., “Modeling of a geothermal standing column well,” Int J Energy Res, vol. 32, no. 4, pp. 306–317, Mar. 2008, doi: 10.1002/er.1355.

B. M. Ng, C. Underwood, and S. Walker, “Numerical modelling of multiple standing column wells for heating and cooling buildings,” in IBPSA 2009 - International Building Performance Simulation Association 2009, 2009.

B. M. Ng, C. P. Underwood, and S. L. Walker, “Standing column wells - Modeling the potential for applications in geothermal heating and cooling,” HVAC and R Research, vol. 17, no. 6, 2011, doi: 10.1080/10789669.2011.588984.

M. Haines and I. Taylor, “Numerical investigation of the flow field around low rise buildings due to a downburst event using large eddy simulation,” Journal of Wind Engineering and Industrial Aerodynamics, vol. 172, 2018, doi: 10.1016/j.jweia.2017.10.028.

Y. Hwang et al., “Cooling performance of a vertical ground-coupled heat pump system installed in a school building,” Renew Energy, vol. 34, no. 3, 2009, doi: 10.1016/j.renene.2008.05.042.

R. Karabacak, E. Güven Acar, H. Kumsar, A. Gökgöz, M. Kaya, and Y. Tülek, “Experimental investigation of the cooling performance of a ground source heat pump system in Denizli, Turkey,” International Journal of Refrigeration, vol. 34, no. 2, 2011, doi: 10.1016/j.ijrefrig.2010.10.009.

O. Ozyurt and D. A. Ekinci, “Experimental study of vertical ground-source heat pump performance evaluation for cold climate in Turkey,” Appl Energy, vol. 88, no. 4, 2011, doi: 10.1016/j.apenergy.2010.10.046.

A. Michopoulos and N. Kyriakis, “Predicting the fluid temperature at the exit of the vertical ground heat exchangers,” Appl Energy, vol. 86, no. 10, 2009, doi: 10.1016/j.apenergy.2009.02.002.

A. Michopoulos, D. Bozis, P. Kikidis, K. Papakostas, and N. A. Kyriakis, “Three-years operation experience of a ground source heat pump system in Northern Greece,” Energy Build, vol. 39, no. 3, 2007, doi: 10.1016/j.enbuild.2006.08.002.

I. Kolo et al., “A comprehensive review of deep borehole heat exchangers (DBHEs): subsurface modelling studies and applications,” Geothermal Energy, vol. 12, no. 1, p. 19, Jun. 2024, doi: 10.1186/s40517-024-00297-3.

Z. Ma et al., “Effects of Boundary Conditions on Performance Prediction of Deep-Buried Ground Heat Exchangers for Geothermal Energy Utilization,” Energies (Basel), vol. 16, no. 13, p. 4874, Jun. 2023, doi: 10.3390/en16134874.

L. Guo, X. Li, Z. Wang, Y. Ma, J. Zhang, and H. Jiang, “Investigation of heating potential and sustainability of medium-deep borehole heat exchanger in severe cold regions,” Mar. 22, 2023. doi: 10.21203/rs.3.rs-2713296/v1.

P. Zhang and B. Guo, “A Feasibility Assessment of Heat Energy Productivity of Geothermal Wells Converted from Oil/Gas Wells,” Sustainability (Switzerland), vol. 16, no. 2, 2024, doi: 10.3390/su16020768.

S. Akbar, N. Fathianpour, and R. Al Khoury, “A finite element model for high enthalpy two-phase flow in geothermal wellbores,” Renew Energy, vol. 94, pp. 223–236, Aug. 2016, doi: 10.1016/j.renene.2016.03.034.

N. BniLam and R. Al-Khoury, “A spectral element model for nonhomogeneous heat flow in shallow geothermal systems,” Int J Heat Mass Transf, vol. 104, pp. 703–717, Jan. 2017, doi: 10.1016/j.ijheatmasstransfer.2016.08.055.

L. Benahmed and K. Aliane, “Simulation and Analysis of a Turbulent Flow Around a Three-Dimensional Obstacle,” Acta Mechanica et Automatica, vol. 13, no. 3, pp. 173–180, Sep. 2019, doi: 10.2478/ama-2019-0023.

L. BENAHMED, K. ALİANE, and A. J. CHAMKHA, “THREE-DIMENSIONAL SIMULATION OF A TURBULENT FLOW AROUND A TAPERED CUBE DUG IN THE MIDDLE,” Journal of Thermal Engineering, vol. 7, no. 2, pp. 256–269, Feb. 2021, doi: 10.18186/thermal.872188.

B. Rostane, K. Aliane, and S. Abboudi, “Three Dimensional Simulation for Turbulent Flow Around Prismatic Obstacle with Rounded Downstream Edge Using the k-ω SST Model,” International Review of Mechanical Engineering (IREME), vol. 9, no. 3, p. 266, May 2015, doi: 10.15866/ireme.v9i3.5719.

B. Rostane and S. Abboudi, “Numerical Study of Laminar Fluid Flow Around Two Heated Wall-Mounted Perforated Cubes in Tandem Arrangement,” International Journal of Heat and Technology, vol. 40, no. 1, pp. 157–166, Feb. 2022, doi: 10.18280/ijht.400119.

S. Heinz, “From Two-Equation Turbulence Models to Minimal Error Resolving Simulation Methods for Complex Turbulent Flows,” Fluids, vol. 7, no. 12, p. 368, Nov. 2022, doi: 10.3390/fluids7120368.

B. Cui, X. Wang, R. Wang, and Z. Xiao, “Numerical investigation of transonic axial compressor rotor flows using an improved transition-sensitized turbulence model,” Physics of Fluids, vol. 33, no. 3, Mar. 2021, doi: 10.1063/5.0043633.

X. Wang, B. Cui, and Z. Xiao, “Numerical investigation on ultra-high-lift low-pressure turbine cascade aerodynamics at low Reynolds numbers using transition-based turbulence models,” Journal of Turbulence, vol. 22, no. 2, 2021, doi: 10.1080/14685248.2020.1849712.

P. Jalili, D. D. Ganji, and S. S. Nourazar, “Investigation of convective-conductive heat transfer in geothermal system,” Results Phys, vol. 10, 2018, doi: 10.1016/j.rinp.2018.06.047.

R. Al-Khoury, Computational Modeling of Shallow Geothermal Systems. 2011. doi: 10.1201/b11462.




DOI: http://dx.doi.org/10.21622/resd.2025.11.1.1150

Refbacks

  • There are currently no refbacks.


Copyright (c) 2025 Lamia Benahmed, Khaled Aliane, Brahim Rostane, Said Abboudi

Renewable Energy and Sustainable Development

E-ISSN: 2356-8569

P-ISSN: 2356-8518

 

Published by:

Academy Publishing Center (APC)

Arab Academy for Science, Technology and Maritime Transport (AASTMT)

Alexandria, Egypt

resd@aast.edu