Impacts of adding porous media on performance of double-pass solar air heater under natural and forced air circulation processes

• Published in: International journal of mechanical sciences 2021-11, Vol.210, p.106738, Article 106738
• Main Authors: Salih, Mothana M. Mohamed, Alomar, Omar Rafae, Yassien, Husam Naufal Saleh
• Format: Article
• Language: English
• Subjects: Double glass; Double pass solar air heater; Natural and forced air circulation conditions; Porous media; Thermal performance
• ISSN: 0020-7403; 1879-2162
• DOI: 10.1016/j.ijmecsci.2021.106738

•Two DPSAH having uniform fins and double glass cover have been experimentally analyzed.•Packed beds above absorber surface of DPSAH-1 has been added.•Experiments have been performed under natural and forced convection at same weather conditions.•Results display that the performance of DPSAH-1 is a considerable higher than DPSAH-2.•Natural convection has a large effect on DPSAH performance than forced convection. This paper presents an experimental work on two trapezoidal double-pass solar air heaters (DPSAH) having double glass covers under natural and forced air circulation conditions to investigate their performances by adding packed beds above the absorber surface on one them for target of comparison. The DPSAH-1 has been operated with adding porous medium, whereas DPSAH-2 has been operated without adding porous medium. Experiments for each model have been performed in winter and compared under identical conditions. The results demonstrate that DPSAH-1 considerably enhances the system performance as compared to DPSAH-2. Results also indicate that the higher efficiency has been obtained when the systems are operated under natural convection. The peak efficiencies of DPSAH-1 and DPSAH-2 have been obtained equal to 87% and 82% for natural convection case and 81% and 67% for forced convection case for lower air mass flowrate, respectively. A considerable temperature difference has been found with natural process as compared to forced process. The advancement in performance of DPSAH-1 confirms that the adding porous medium and types of air circulation have considerable impact on heat transfer rate. Therefore, it can be concluded that DPSAH-1 is better than DPSAH-2, particularly for forced convection case including the applications that needs high temperatures and vice-verse. [Display omitted]