Document Type : Research Paper


1 Department of Mechanical Engineering, University of Al-Qadisiyah, Al Diwaniyah, Al-Qadisiyah, 58001, Iraq .

2 Mechanical Engineering Dept., University of Technology-Iraq, Alsina’a street, 10066 Baghdad, Iraq.


The two-dimensional numerical simulations focused on fluid flow and heat transfer within a solar air heater (SAH) channel incorporating copper metal foam with a porosity of 90% were carried out in this study. The Local Thermal Non-equilibrium (LTNE) and Darcy-Extended Forchheimer (DEF) models were employed to predict fluid and thermal transport in the partially porous SAH channel. In the free flow zone, the  turbulence model was utilized. The thermal and thermo-hydraulic performances of SAH were examined concerning several factors, including pore density ( ), Reynolds number ( ), and dimensionless foam height ( ). The results demonstrate that inserting a porous substrate into the SAH can substantially increase heat transmission. This enhancement ranges from 4.4 to 18.04 times compared to an empty duct for  at . Moreover, increased porous layer height and pore density lead to a corresponding increase in pressure drop. Evaluating both the improvement in heat transmission and the associated pressure penalty, the case with ,  and  demonstrate superior overall performance, boasting a higher Thermal Performance Factor ( ) of 2.82 when compared to an empty channel. This work presents significant findings on optimizing metal foam applications in SAH systems, offering new insights into the field.

Graphical Abstract


  • Fluid flow and heat transfer in an SAH channel with metal foam were simulated
  • The LTNE and DEF models were used.
  • The thermo-hydraulic performance of SAH was analyzed, considering several key factors.
  • Compared to the empty SAH duct, Nu rises 9-10.6 times and friction factor by 53.5-56.6 times.
  • TPF varies from 2.33 to 2.82 at Hf =0.6 and ω=10 PPI.


Main Subjects

  1. F. Xia, et al., Enhanced thermal performance of a flat-plate solar collector inserted with porous media: A numerical simulation study, Therm. Sci. Eng. Prog., 44 (2023) 102063.
  2. Liu, et al., Game theory-based renewable multi-energy system design and subsidy strategy optimization, Adv. Appl. Energy, 2 (2021) 100024.
  3. Yan, J., Energy systems in transition: challenges and opportunities, Adv. Appl. Energy, 1 (2020) 100005.
  4. A. Sakhaei, and M.S. Valipour, Performance enhancement analysis of The flat plate collectors: A comprehensive review, Renewable Sustainable Energy Rev., 102 (2019) 186-204.
  5. Choudhury, P.K. and D.C. Baruah, Solar air heater for residential space heating, Energy Ecol. Environ., 2 (2017) 387-403.
  6. Saxena, et al., Experimental studies of latent heat storage based solar air heater for space heating: A comparative analysis, J. Build. Eng., 69 (2023) 106282.
  7. Al-damook, and W.H. Khalil, Experimental evaluation of an unglazed solar air collector for building space heating in Iraq, Renewable Energy, 112 (2017) 498-509.
  8. Kumara, et al., Performance improvement of a solar desalination system assisted with solar air heater: An experimental approach, J. Indian Chem. Soc., 79 (2020) 1967-1972.
  9. García-Valladares, et al., Solar thermal drying plant for agricultural products. Part 1: Direct air heating system. Renewable Energy, 148 (2020) 1302-1320.
  10. Lingayat, R. Zachariah, and A. Modi, Current status and prospect of integrating solar air heating systems for drying in various sectors and industries, Sustainable Energy Technol. Assess., 52 (2022) 102274.
  11. Gorjian, et al., A review on recent advancements in performance enhancement techniques for low-temperature solar collectors, Energy Convers. Manage., 222 (2020) 113246.
  12. K. Al‐Chlaihawi, M.R. Hasan, and A.L. Ekaid, Compound passive heat transfer augmentation techniques: A comprehensive review, Heat Transfer.53 (2023) 363-421.
  13. Prakash, and R.P. Saini, Use of artificial roughness for performance enhancement of solar air heaters—a review. Int. J. Green Energy, 16 (2019) 551-572.
  14. K. Al‐Chlaih awi, K.K.I., M.R. Hasan, and A.L. Ekaid, Thermohydraulic performance assessment of a solar air heater with equilateral‐triangular, trapezoidal, and square sectional ribs on the absorber plate: A comparative study, Heat Transfer, 53 (2023) 441-471.
  15. K. Al-Chlaihawi, B.H. Alyas, and A.A. Badr, CFD Based Numerical Performance Assessment of a Solar Air Heater Duct Roughened by Transverse-Trapezoidal Sectioned Ribs, Int. J. Heat Technol., 41 (2023) 1273-1281,
  16. H. Abu-Hamdeh, R.A. Alsulami, and R.I. Hatamleh, A case study in the field of building sustainability energy: Performance enhancement of solar air heater equipped with PCM: A trade-off between energy consumption and absorbed energy, J. Build. Eng., 48 (2022) 103903.
  17. Assadeg, et al., Energetic and exergetic analysis of a new double pass solar air collector with fins and phase change material, Sol. Energy, 226 (2021) 260-271.
  18. Kumar, S. Kumar Verma, and V. Kumar Sharma, Performance enhancement analysis of triangular solar air heater coated with nanomaterial embedded in black paint, Mater. Today: Proc., 26 (2020) 2528-2532.
  19. Kumar, and P. Chand, Performance enhancement of solar air heater using herringbone corrugated fins, Energy, 127 (2017) 271-279.
  20. C. Ifrim, and O.V. Grosu. Review of thermal performance enhancement of Solar Air Heater using baffles on absorber plate, International Conference on Development and Application Systems (DAS). 2022. IEEE.
  21. Chand, P. Chand, and H. K. Ghritlahre, Thermal performance enhancement of solar air heater using louvered fins collector, Sol. Energy, 239 (2022) 10-24.
  22. Zhu, and Y. Xuan, Pore scale numerical simulation of heat transfer and flow in porous volumetric solar receivers, Appl. Therm. Eng., 120 (2017) 150-159.
  23. F. Jouybari, and T.S. Lundström, Performance improvement of a solar air heater by covering the absorber plate with a thin porous material, Energy, 190 (2020) 116437.
  24. Chen, M. Gu, and D. Peng, Heat transfer performance analysis of a solar flat-plate collector with an integrated metal foam porous structure filled with paraffin, Appl. Therm. Eng., 30 (2010) 1967-1973.
  25. Rashidi, M. Bovand, and J.A. Esfahani, Heat transfer enhancement and pressure drop penalty in porous solar heat exchangers: A sensitivity analysis, Energy Convers. Manage., 103 (2015) 726-738.
  26. Bovand, S. Rashidi, and J.A. Esfahani, Heat transfer enhancement and pressure drop penalty in porous solar heaters: Numerical simulations, Sol. Energy, 123 (2016) 145-159.
  27. T. Jamal-Abad, S. Saedodin, and M. Aminy, Heat transfer in concentrated solar air-heaters filled with a porous medium with radiation effects: A perturbation solution, Renewable Energy, 91 (2016) 147-154.
  28. J. Jouybari, et al., Experimental investigation of thermal performance and entropy generation of a flat-plate solar collector filled with porous medial, Appl. Therm. Eng., 127 (2017) 1506-1517.
  29. Saedodin, et al., Performance evaluation of a flat-plate solar collector filled with porous metal foam: Experimental and numerical analysis, Energy Convers. Manage., 153 (2017) 278-287.
  30. J. Jouybari, et al., Effects of porous material and nanoparticles on the thermal performance of a flat plate solar collector: An experimental study, Renewable Energy, 114 (2017) 1407-1418.
  31. J. Jouybari, et al., Analytical investigation of forced convection heat transfer in a flat-plate solar collector filled with a porous medium by considering radiation effect, J. Porous Media, 21 (2018).
  32. Valizade, M., M. Heyhat, and M. Maerefat, Experimental study of the thermal behavior of direct absorption parabolic trough collector by applying copper metal foam as volumetric solar absorption, Renewable Energy, 145 (2020) 261-269.
  33. Anirudh, and S. Dhinakaran, Performance improvement of a flat-plate solar collector by inserting intermittent porous blocks, Renewable Energy, 145 (2020) 428-441.
  34. Anirudh, and S. Dhinakaran, Numerical analysis of the performance improvement of a flat-plate solar collector using conjugated porous blocks, Renewable Energy, 172 (2021) 382-391.
  35. Diganjit, N. Gnanasekaran, and M. Mobedi, Numerical Study for Enhancement of Heat Transfer Using Discrete Metal Foam with Varying Thickness and Porosity in Solar Air Heater by LTNE Method, Energies, 15 (2022) 8952.
  36. G. Fadhala, E.M. Fayyadh, and A.F. Mohammed, Experimental investigation on the thermal-hydraulic performance of channel with gradient metal foam baffles, FME Transactions, 51 (2023) 14-22.
  37. Fu, et al., A novel structure design and numerical analysis of porous media-assisted enhanced thermal performance of flat-plate solar collector, Therm. Sci. Eng. Prog., 40 (2023) 101777.
  38. Xia, et al., Numerical Study on the Enhanced Thermal Performance of the Porous Media-Assisted Flat-Plate Solar Collector, Int. J. Energy Res., 2023 (2023) 2244771.
  39. A. Handbook, and G. Atlanta, UAS: American Society of Heating, Refrigerating and Air Conditioning Engineers, 2003.
  40. V. Calmidi, and R.L. Mahajan, Forced convection in high porosity metal foams. J. Heat Transfer, 122 (2000) 557-565.
  41. Alazmi, and K. Vafai, Constant wall heat flux boundary conditions in porous media under local thermal non-equilibrium conditions, Int. J. Heat Mass Transfer, 45 (2002) 3071-3087.
  42. Liu, G. Xie, and T.W. Simon, Turbulent flow and heat transfer enhancement in rectangular channels with novel cylindrical grooves, Int. J. Heat Mass Transfer, 81 (2015) 563-577.
  43. M. Patel, S.V. Jain, and V.J. Lakhera, Thermo-hydraulic performance analysis of a solar air heater roughened with reverse NACA profile ribs, Appl. Therm. Eng., 170 (2020) 114940.
  44. Webb, and E. Eckert, Application of rough surfaces to heat exchanger design, Int. J. Heat Mass Transfer, 15 (1972) 1647-1658.
  45. H. Jadhav, and N. Gnanasekaran, Optimum design of heat exchanging device for efficient heat absorption using high porosity metal foams, Int. Commun. Heat Mass Transfer, 126 (2021) 105475.
  46. M. K. Ali, and S.L. Ghashim, Numerical analysis of the heat transfer enhancement by using metal foam, Case Stud. Therm. Eng., 49 (2023) 103336.
  47. Kotresha, and N. Gnanasekaran, Numerical simulations of fluid flow and heat transfer through aluminum and copper metal foam heat exchanger–a comparative study, Heat Transfer Eng., 41 (2019) 637-649.
  48. Lin, et al., Comparison and analysis of heat transfer in aluminum foam using local thermal equilibrium or non-equilibrium model, Heat Transfer Eng., 37 (2016) 314-322.
  49. V. Calmidi, Transport phenomena in high porosity fibrous metal foams. 1998: University of Colorado at Boulder.
  50. Lu, C. Zhao, and S. Tassou, Thermal analysis on metal-foam filled heat exchangers. Part I: Metal-foam filled pipes, Int. J. Heat Mass Transfer, 49 (2006) 2751-2761.
  51. Boomsma, and D. Poulikakos, On the effective thermal conductivity of a three-dimensionally structured fluid-saturated metal foam, Int. J. Heat Mass Transfer, 44 (2001) 827-836.
  52. Dukhan, Ö. Bağcı, and M. Özdemir, Thermal development in open-cell metal foam: An experiment with constant wall heat flux, Int. J. Heat Mass Transfer, 85 (2015) 852-859.
  53. E. Nimvari, N.F. Jouybari, and Q. Esmaili, A new approach to mitigate intense temperature gradients in ceramic foam solar receivers, Renewable Energy, 122 (2018) 206-215.
  54. Kurtbas, and N. Celik, Experimental investigation of forced and mixed convection heat transfer in a foam-filled horizontal rectangular channel, Int. J. Heat Mass Transfer, 52 (2009) 1313-1325.
  55. Dukhan, M.A. Al-Rammahi, and A.S. Suleiman, Fluid temperature measurements inside metal foam and comparison to Brinkman–Darcy flow convection analysis, Int. J. Heat Mass Transfer, 67 (2013) 877-884.
  56. P. Breugem, and B.-J. Boersma, Direct numerical simulations of turbulent flow over a permeable wall using a direct and a continuum approach, Phys. fluids, 17 (2005).
  57. Chandesris, et al., Direct numerical simulation of turbulent heat transfer in a fluid-porous domain, Phys. Fluids, 25 (2013) 125110.
  58. Qu, H. Xu, and W. Tao, Fully developed forced convective heat transfer in an annulus partially filled with metallic foams: an analytical solution, Int. J. Heat Mass Transfer, 55 (2012) 7508-7519.
  59. Lu, T. Zhang, and M. Yang, Analytical solution of forced convective heat transfer in parallel-plate channel partially filled with metallic foams, Int. J. Heat Mass Transfer, 100 (2016) 718-727.
  60. E. Nimvari, M. Maerefat, and M. El-Hossaini, Numerical simulation of turbulent flow and heat transfer in a channel partially filled with a porous media, Int. J. Therm. Sci., 60 (2012) 131-141.
  61. Sethi, and N. Thakur, Correlations for solar air heater duct with dimpled shape roughness elements on absorber plate, Sol. Energy, 86 (2012) 2852-2861.