Performance of New Absorber Coating Strategy in Solar Air Heaters: An Experimental Case Study

Document Type : Original Article


1 Mechanical Engineering Department, Higher Education Complex of Bam, Bam, Iran

2 Mechanical Engineering Faculty, Sirjan University of Technology, Kerman, Iran


Asphalt materials commonly have high absorption coefficients, and their surface temperature reaches as high as 80 oC during daytime hours since their surfaces are exposed to solar radiation for long periods. Hence, asphalt pavements can easily be converted to solar air heaters (SAHs) to collect solar energy. Even though asphalt materials have low thermal conductivity, resulting in a weak convection heat exchange rate between the flowing air and asphalt surface. The current experimental study analyzes utilizing aluminum shavings as asphalt coating materials to improve SAHs’ thermal performance. To this aim, a serpentine SAH prototype was constructed, and several sensors were utilized to monitor its dynamic thermal response. Black-painted aluminum shavings were utilized as coating materials to improve the convective heat exchange rate and increase the roughness of the absorber surface. Two scenarios were considered, including the uncoated absorber plate and coated one with 0.2 kg aluminum shavings. The experiments were carried out for two air mass flow rates of 0.02 kg/s and 0.03 kg/s under field conditions. Based on the air mass flow rate, the coated absorber reaches higher temperatures, approximately 5 oC to 9 oC, than the uncoated one. The acquired results illustrate that the coated SAH has nearly 4 oC to 5 oC higher maximum exhaust air temperature; hence, the coating strategy improves the thermal efficiency by 24.75% and 44% in two air mass flow rates of 0.02 kg/s and 0.03 kg/s, respectively.


Main Subjects

  1. Nnamchi, S., Nnamchi, O., Sangotayo, E., Ismael, S., Nkurunziza, O. and Gabriel, V., 2020. “Design and simulation of air-solar preheating unit: An improved design of a flat plate solar collector”. Iranian (Iranica) Journal of Energy & Environment, 11(2), pp.97-108. Doi: 10.5829/ijee.2020.11.02.02
  2. Gandjalikhan Nassab, S. and Moein Addini, M., 2021. “Performance augmentation of solar air heater for space heating using a flexible flapping guide winglet”. Iranian (Iranica) Journal of Energy & Environment, 12(2), pp.161-172.
    Doi: 10.5829/ijee.2021.12.02.09
  3. Farzan, H., Ameri, M. and Jaafarian, S., 2020. “Effectiveness of continuous and discontinuous-flow strategies in heat dynamics and performance of asphalt solar collector: An experimental study”. Iranian (Iranica) Journal of Energy & Environment, 11(2), pp.137-145. Doi: 10.5829/ijee.2020.11.02.07
  4. Zhu, J., Jia, H., Cheng, X., Huang, X., Liu, X. and Guo, J., 2019. “The design and performance evaluation of a high-efficient flexible solar air heater based on transparent spacer fabric composite”. Solar Energy Materials and Solar Cells, 201, pp.110089. Doi: 10.1016/j.solmat.2019.110089
  5. Ameri, M., Farzan, H. and Nobari, M., 2021. “Evaluation of different glazing materials, strategies, and configurations in flat plate collectors using glass and acrylic covers: An experimental assessment”. Iranian (Iranica) Journal of Energy & Environment, 12(4), pp.297-306. Doi: 10.5829/ijee.2021.12.04.03
  6. Sakhaei, S.A. and Valipour, M.S., 2019. “Performance enhancement analysis of the flat plate collectors: A comprehensive review”. Renewable and Sustainable Energy Reviews, 102, pp.186-204. Doi: 10.1016/j.rser.2018.11.014
  7. Rai, S., Chand, P. and Sharma, S., 2016. “Investigation of an offset finned solar air heater based on energy and exergy performance”. Iranian (Iranica) Journal of Energy & Environment, 7(3), pp.212-220. Doi: 10.5829/idosi.ijee.2016.07.03.01
  8. El-Sebaii, A. and Al-Snani, H., 2010. “Effect of selective coating on thermal performance of flat plate solar air heaters”. Energy, 35(4), pp.1820-1828. Doi: 10.1016/
  9. Zhang, K., Hao, L., Du, M., Mi, J., Wang, J.-N. and Meng, J.-p., 2017. “A review on thermal stability and high temperature induced ageing mechanisms of solar absorber coatings”. Renewable and Sustainable Energy Reviews, 67, pp.1282-1299.
    Doi: 10.1016/j.rser.2016.09.083
  10. Malliga, T.V. and Rajasekhar, R.J., 2017. “Preparation and characterization of nanographite-and cuo-based absorber and performance evaluation of solar air-heating collector”. Journal of Thermal Analysis and Calorimetry, 129(1), pp.233-240.
    Doi: 10.1007/s10973-017-6155-1
  11. Arunkumar, T., Murugesan, D., Raj, K., Denkenberger, D., Viswanathan, C., Rufuss, D.D.W. and Velraj, R., 2019. “Effect of nano-coated CuO absorbers with PVA sponges in solar water desalting system”. Applied Thermal Engineering, 148, pp.1416-1424. Doi:10.1016/j.applthermaleng.2018.10.129
  12. Abdelkader, T.K., Zhang, Y., Gaballah, E.S., Wang, S., Wan, Q. and Fan, Q., 2020. “Energy and exergy analysis of a flat-plate solar air heater coated with carbon nanotubes and cupric oxide nanoparticles embedded in black paint”. Journal of Cleaner Production, 250, pp.119501. Doi: 10.1016/j.jclepro.2019.119501
  13. Abdelkader, T.K., Fan, Q., Gaballah, E.S., Wang, S. and Zhang, Y., 2020. “Energy and exergy analysis of a flat-plate solar air heater artificially roughened and coated with a novel solar selective coating”. Energies, 13(4), pp.997. Doi:10.1016/j.jclepro.2019.119501
  14. Das, B., Mondol, J.D., Negi, S., Smyth, M. and Pugsley, A., 2020. “Experimental performance analysis of a novel sand coated and sand filled polycarbonate sheet based solar air collector”. Renewable Energy, 164, pp.990-1004.
    Doi: 10.1016/j.renene.2020.10.054
  15. Akpinar, E.K. and Koçyiğit, F., 2010. “Energy and exergy analysis of a new flat-plate solar air heater having different obstacles on absorber plates”. Applied Energy, 87(11), pp.3438-3450.
    Doi: 10.1016/j.apenergy.2010.05.017
  16. Ho, C.-D., Chang, H., Wang, R.-C. and Lin, C.-S., 2012. “Performance improvement of a double-pass solar air heater with fins and baffles under recycling operation”. Applied Energy, 100, pp.155-163. Doi: 10.1016/j.apenergy.2012.03.065
  17. El-Sebaii, A., Aboul-Enein, S., Ramadan, M., Shalaby, S. and Moharram, B., 2011. “Investigation of thermal performance of-double pass-flat and v-corrugated plate solar air heaters”. Energy, 36(2), pp.1076-1086. Doi: 10.1016/
  18. El-Sebaii, A., Aboul-Enein, S., Ramadan, M., Shalaby, S. and Moharram, B., 2011. “Thermal performance investigation of double pass-finned plate solar air heater”. Applied Energy, 88(5), pp.1727-1739. Doi: 10.1016/j.apenergy.2010.11.017
  19. El-Khawajah, M., Aldabbagh, L. and Egelioglu, F., 2011. “The effect of using transverse fins on a double pass flow solar air heater using wire mesh as an absorber”. Solar Energy, 85(7), pp.1479-1487. Doi: 10.1016/j.solener.2011.04.004
  20. Alta, D., Bilgili, E., Ertekin, C. and Yaldiz, O., 2010. “Experimental investigation of three different solar air heaters: Energy and exergy analyses”. Applied Energy, 87(10), pp.2953-2973. Doi: 10.1016/j.apenergy.2010.04.016
  21. Ravi, R.K. and Saini, R.P., 2016. “A review on different techniques used for performance enhancement of double pass solar air heaters”. Renewable Sustainable Energy Reviews, 56, pp.941-952. Doi: 10.1016/j.rser.2015.12.004
  22. Alam, T. and Kim, M.-H., 2017. “Performance improvement of double-pass solar air heater–a state of art of review”. Renewable Sustainable Energy Reviews, 79, pp.779-793.
    Doi: 10.1016/j.rser.2017.05.087
  23. Mahmood, A., Aldabbagh, L. and Egelioglu, F., 2015. “Investigation of single and double pass solar air heater with transverse fins and a package wire mesh layer”. Energy Conversion Management, 89, pp.599-607.
    Doi: 10.1016/j.enconman.2014.10.028
  24. Nowzari, R., Mirzaei, N. and Aldabbagh, L., 2015. “Finding the best configuration for a solar air heater by design and analysis of experiment”. Energy Conversion Management, 100, pp.131-137. Doi: 10.1016/j.enconman.2015.04.058
  25. Vaziri, R., İlkan, M. and Egelioglu, F., 2015. “Experimental performance of perforated glazed solar air heaters and unglazed transpired solar air heater”. Solar Energy, 119, pp.251-260.
    Doi: 10.1016/j.solener.2015.06.043
  26. Sahu, M.K. and Prasad, R.K., 2016. “Exergy based performance evaluation of solar air heater with arc-shaped wire roughened absorber plate”. Renewable Energy, 96, pp.233-243. Doi:10.1016/j.renene.2016.04.083
  27. Ravi, R.K. and Saini, R., 2018. “Effect of roughness elements on thermal and thermohydraulic performance of double pass solar air heater duct having discrete multi v-shaped and staggered rib roughness on both sides of the absorber plate”. Experimental Heat Transfer, 31(1), pp.47-67. Doi: 10.1080/08916152.2017.1350217
  28. Priyam, A. and Chand, P., 2018. “Effect of wavelength and amplitude on the performance of wavy finned absorber solar air heater”. Renewable Energy, 119, pp.690-702.
    Doi: 10.1016/j.renene.2017.12.010
  29. Kumar, R. and Chand, P., 2017. “Performance enhancement of solar air heater using herringbone corrugated fins”. Energy, 127, pp.271-279. Doi: 10.1016/
  30. Kumar, A. and Layek, A., 2019. “Energetic and exergetic performance evaluation of solar air heater with twisted rib roughness on absorber plate”. Journal of Cleaner Production, 232, pp.617-628. Doi: 10.1016/j.jclepro.2019.05.363
  31. Kabeel, A., Hamed, M.H., Omara, Z. and Kandeal, A., 2018. “Influence of fin height on the performance of a glazed and bladed entrance single-pass solar air heater”. Renewable Solar Energy, 162, pp.410-419. Doi: 10.1016/j.solener.2018.01.037
  32. Singh, S., 2020. “Experimental and numerical investigations of a single and double pass porous serpentine wavy wiremesh packed bed solar air heater”. Renewable Energy, 145, pp.1361-1387.
    Doi: 10.1016/j.renene.2019.06.137
  33. Singh, S., Singh, A. and Chander, S., 2019. “Thermal performance of a fully developed serpentine wavy channel solar air heater”. Journal of Energy Storage, 25, pp.100896.
    Doi: 10.1016/j.est.2019.100896
  34. Afshari, F., Sözen, A., Khanlari, A., Tuncer, A.D. and Şirin, C., 2020. “Effect of turbulator modifications on the thermal performance of cost-effective alternative solar air heater”. Renewable Energy, 158, pp.297-310.
    Doi: 10.1016/j.renene.2020.05.148
  35. Gholami, A., Ajabshirchi, Y. and Ranjbar, S.F., 2019. “Thermo-economic optimization of solar air heaters with arcuate-shaped obstacles”. Journal of Thermal Analysis Calorimetry, 138(2), pp.1395-1403. Doi: 10.1007/s10973-019-08273-x
  36. Luca, J. and Mrawira, D., 2005. “New measurement of thermal properties of superpave asphalt concrete”. Journal of Materials in Civil Engineering, 17(1), pp.72-79. Doi: 10.1061/(ASCE)0899-1561(2005)17:1(72)
  37. Yavuzturk, C., Ksaibati, K. and Chiasson, A., 2005. “Assessment of temperature fluctuations in asphalt pavements due to thermal environmental conditions using a two-dimensional, transient finite-difference approach”. Journal of Materials in Civil Engineering, 17(4), pp.465-475. Doi: 10.1061/(ASCE)0899-1561(2005)17:4(465)
  38. Gui, J., Phelan, P.E., Kaloush, K.E. and Golden, J.S., 2007. “Impact of pavement thermophysical properties on surface temperatures”. Journal of Materials in Civil Engineering, 19(8), pp.683-690. Doi: 10.1061/(ASCE)0899-1561(2007)19:8(683)
  39. Guldentops, G., Nejad, A.M., Vuye, C. and Rahbar, 2015. N., “Performance of a pavement solar energy collector: Model development and validation”. Applied Energy, 163, pp.180-189. Doi: 10.1016/j.apenergy.2015.11.010
  40. Kline, S.J., 1985. “The purpose of uncertainty analysis”. Journal of Fluids Engineering, 107, pp.163-163.