Document Type : Original Article


1 Department of Mechanical Engineering, Shahid Bahonar University of Kerman, Kerman, Iran

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


Glass plates have been commonly used as collectors’ covers due to technical feasibility, high transmissivity in shortwave solar irradiation, and low transmissivity in long-wavelengths. However, they are vulnerable to stones and hail. Plastic plates have high transmissivity in shortwaves but also have transmission bands in the middle of the thermal radiation spectrum. The current study represents an experimental assessment of different covering strategies, including single acrylic-cover, single glass-cover, double glass- acrylic cover, and double glass-cover. Two solar air heaters (SAHs) prototypes were constructed for this study. The acquired experimental runs illustrated that the single glass-covered SAH represents higher thermal performance than the single acrylic-covered SAH due to the lower transmissivity of glass plates in long wavelengths. The double-covered SAHs have higher performance than the similar single-covered SAHs. In the double-covered SAHs, the convective-radiant heat loss is reduced. However, increasing the cover number improves the radiant resistance to solar irradiation and reduces the collector performance when solar irradiation is insufficient and the absorber temperature is low, especially at the beginning of daytime hours. The SAH using a double-glass cover is preferable; however, the heat dynamics of the double glass- acrylic-covered SAH are so close to the double glass-covered one, and the acrylic plate is more resistant to harsh ambient conditions.


  1. Zwalnan, S., Caleb, N., Mangai, M. and Sanda, N., 2021. “Comparative Analysis of Thermal Performance of a Solar Water Heating System Based on the Serpentine and Risers-Head Configurations”, Journal of Renewable Energy and Environment, 8(2), pp: 21-30,
  2. Gandjalikhan Nassab, S. and Moein Addini, M., 2021. “Effect of Radiative Filling Gas in Compound Parabolic Solar Energy Collectors”, Iranian (Iranica) Journal of Energy and Environment, 12(3), pp: 181-191,
  3. 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 and Environment, 12(2), pp: 161-172,
  4. Pandey, K. M. and Chaurasiya, R., 2017. “A review on analysis and development of solar flat plate collector”, Renewable and Sustainable Energy Reviews, 67, pp: 641-650,
  5. Chabane, F. and Sekseff, E., 2018. “Experimental study of a solar air collector with doubles glazed”, Iranian (Iranica) Journal of Energy and Environment, 9(3), pp: 163-167,
  6. Daghigh, R. and Shafieian, A., 2016. “Thermal performance of a double-pass solar air heater”, Journal of Renewable Energy and Environment, 3(2), pp: 35-46,
  7. 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 and Environment, 11(2), pp: 97-108,
  8. Ghritlahre, H. K., Chandrakar, P. and Ahmad, A., 2020. “Application of ANN model to predict the performance of solar air heater using relevant input parameters”, Sustainable Energy Technologies and Assessments, 40, pp: 100764,
  9. Desisa, D. G. and Shekata, G. D., 2020. “Performance Analysis of Flat-Plate and V-groove Solar Air Heater Through CFD Simulation”, International Journal of Renewable Energy Development, 9(3), pp: 369-381.
  10. Samdarshi, S. and Mullick, S., 1990. “Analysis of the top heat loss factor of flat plate solar collectors with single and double glazing”, International Journal of Energy Research, 14(9), pp: 975-990,
  11. Samdarshi, S. and Mullick, S., 1991. “Analytical equation for the top heat loss factor of a flat-plate collector with double glazing”, Solar Energy Engineering, pp: 117-122.
  12. Akhtar, N. and Mullick, S., 2007. “Computation of glass-cover temperatures and top heat loss coefficient of flat-plate solar collectors with double glazing”, Energy 32(7), pp: 1067-1074,
  13. Das, S. and Chakraverty, A., 1991. “Performance of a solar collector with different glazing materials and their degradation under the condition prevailing in a solar collector”, Energy Conversion Management, 31(3), pp: 233-242,
  14. Yang, R. and Wang, P.-L., 2001. “A simulation study of performance evaluation of single-glazed and double-glazed collectors/regenerators for an open-cycle absorption solar cooling system”, Solar Energy, 71(4), pp: 263-268,
  15. Maatouk, K., 2006. “Non-gray radiative and conductive heat transfer in single and double glazing solar collector glass covers”, International Journal of Thermal Sciences, 45(6), pp: 579-585,
  16. Hatami, N. and Bahadorinejad, M., 2008. “Experimental determination of natural convection heat transfer coefficient in a vertical flat-plate solar air heater”, Solar Energy, 82(10), pp: 903-910,
  17. Tchinda, R., 2009. “A review of the mathematical models for predicting solar air heaters systems”, Renewable Sustainable Energy Reviews, 13(8), pp: 1734-1759,
  18. Giovannetti, F., Föste, S., Ehrmann, N. and Rockendorf, G., 2014. “High transmittance, low emissivity glass covers for flat plate collectors: Applications and performance”, Solar Energy, 104, pp: 52-59,
  19. Subiantoro, A. and Ooi, K. T., 2013. “Analytical models for the computation and optimization of single and double glazing flat plate solar collectors with normal and small air gap spacing”, Applied Energy, 104, pp: 392-399,
  20. Akhtar, N. and Mullick, S., 2012. “Effect of absorption of solar radiation in glass-cover (s) on heat transfer coefficients in upward heat flow in single and double glazed flat-plate collectors”, International Journal of Heat Mass Transfer, 55(1-3), pp: 125-132,  
  21. Bahrehmand, D. and Ameri, M., 2015. “Energy and exergy analysis of different solar air collector systems with natural convection”, Renewable Energy, 74, pp: 357-368,
  22. Bahrehmand, D., Ameri, M. and Gholampour, M., 2015. “Energy and exergy analysis of different solar air collector systems with forced convection”, Renewable Energy, 83, pp: 1119-1130,
  23. Manikandan, J. and Sivaraman, B., 2016. “Comparative studies on thermal efficiency of single and double glazed flat plate solar water heater”, ARPN Journal of Engineering Applied Sciences, 11(9), pp: 5521-5526.
  24. Vettrivel, H. and Mathiazhagan, P., 2017. “Comparison study of solar flat plate collector with single and double glazing systems”, International Journal of Renewable Energy Research, 7(1), pp: 266-274.
  25. Dondapati, R. S., Agarwal, R., Saini, V., Vyas, G. and Thakur, J., 2018. “Effect of glazing materials on the performance of solar flat plate collectors for water heating applications”, Materials Today: Proceedings, 5(14), pp: 27680-27689,
  26. Singh, V. V., Thakur, J., Agarwal, R., Vyas, G. and Dondapati, R. S., 2018. “Computational Evaluation of Thermal and Hydraulic Characteristics of Flat-Plate Solar Collector for Different Glazing Material”, Materials Today: Proceedings, 5(14), pp: 28211-28220,
  27. Ganesh Kumar, P., Meikandan, M., Sakthivadivel, D. and Vigneswaran, V., 2018. “Selection of optimum glazing material for solar thermal applications using TOPSIS methodology”, International Journal of Ambient Energy, pp: 1-5,
  28. Renuka, M., Balaji, K., Sakthivadivel, D., Meikandan, M. and Ganesh Kumar, P., 2019. “Selection of optimal glazing material for solar thermal applications using grey relational analysis”, International Journal of Ambient Energy, pp: 1-5,
  29. Osorio, J. D. and Rivera-Alvarez, A., 2019. “Performance analysis of parabolic trough collectors with double glass envelope”, Renewable Energy, 130, pp: 1092-1107,
  30. Tekkalmaz, M., Timuralp, Ç. and Sert, Z., 2020. “The Effect of the Use of Different Cover Materials on Heat Transfer in Flat Solar Collectors”, Journal of Thermal Engineering, 6(5), pp: 829-842,
  31. Filipović, P., Dović, D., Ranilović, B. and Horvat, I., 2019. “Numerical and experimental approach for evaluation of thermal performances of a polymer solar collector”, Renewable Sustainable Energy Reviews, 112, pp: 127-139,
  32. Bergman, T. L., Incropera, F. P., DeWitt, D. P. and Lavine, A. S., 2011. Fundamentals of heat and mass transfer. John Wiley & Sons.
  33. Kline, S. J., 1953. “Describing uncertainty in single sample experiments”, Mechanical Engineering, 75, pp: 3-8.
  34. Coventry, J. and Lovegrove, K., 2003. “Development of an approach to compare the ‘value’of electrical and thermal output from a domestic PV/thermal system”, Solar Energy, 75(1), pp: 63-72,