Investigation the effect of porosity on the thermohydraulic performance of a solar air collector with perforated obstacles

Subject Areas : Renewable Energy

Amin Ghalenoei ¹ , Majid Sabzpooshani ²

1 - PhD student, Energy Conversion Department, Mechanical Engineering Faculty, University of Kashan, Kashan, Iran.
2 - PhD, Energy Conversion Department, Mechanical Engineering Faculty and Energy Research Institute, University of Kashan, Kashan, Iran. *(Corresponding Author)

Received: 2021-04-10 Accepted : 2022-08-31 Published : 2023-07-23

Keywords: Solar air heater, perforated obstacles, Pressure drop, thermal efficiency effective efficiency,

Abstract :

Background and Objective: Due to undesirable thermo-physical properties of the air, the solar air collectors do not benefit from the high thermal efficiency and need to be improved with the help of different methods. In this study, the effects of using various obstacles on the thermohydraulic performance of a collectors were examined experimentally and compared to the performance of a simple collector.    Material and Methodology: A solar air collector was designed, built and tested under the environmental conditions of Abadan city in Khuzestan province. Three different perforated obstacles with three hole sizes (3, 4 and 5 cm) were placed on the absorber plate. Measured parameters include the temperature of inlet and outlet air, absorber plate, pressure drop and solar radiation. Measurements were made for two different air flux (0.0218 and 0.0364 kg/s).   Findings: It has become clear that using various perforated obstacles increases the temperature difference between inlet and outlet air and subsequently their efficiencies compared to a simple conventional collector. It was also noted that in all cases, the increase in mass flowrate causes increasing the effective and thermal efficiency of system and decreasing the temperature difference between inlet and outlet air. Temperature difference in the best case (perforated obstacles with 3 cm holes) for each of the two flowrates increases twice compared to the simple collector. Also, the highest amount of average efficiency for two flowrates is 68% and 83% and the average effective efficiency is 28.4% and 34.1%.  Discussion and Conclusion: With the reduction of sizes of the holes in the perforated obstacles, the rate of heat transfer and subsequently the thermal efficiency of the collector will increase due to increasing the turbulence of the flow. This causes the pressure drop to rise up as well but also has a positive effect of increasing the temperature difference which dominates the negative effect of the pressure drop and eventually it becomes clear that there is a direct relation between increasing the effective efficiency with reducing the size of the holes.

References:

1. http://www.mimt.gov.ir/


2. Ahmed-Zaid, A., Messaoudi, H., Abenne, A., Le Ray, M., Desmons, J. Y., Abed, B., 1999. Experimental study of thermal performance improvement of a solar air flat plate collector through the use of obstacles: application for the drying of yellow onion. Int. J. Energy Res., Vol. 23, pp. 1083-199.


3. Abene, A., Dubois, V., Le Ray, M., Ouagued, A., 2004. Study of a solar air flat plate collector: use of obstacles and application for the drying of grape. Journal of Food Engineering, Vol. 65, pp. 15–22.


4. Handoyo, E. A., Ichsani, D., Prabowo, Sutardi, 2016. Numerical studies on the effect of delta-shaped obstacles’ spacing on the heat transfer and pressure drop in v-corrugated channel of solar air heater, Solar Energy, Vol. 131, pp. 47-60.


5. Kulkarni, K., Afzal, A., Kim, K.Y., 2015. Multi-objective optimization of solar air heater with obstacles on absorber plate. Solar Energy, Vol. 114, pp. 364–377.


6. Alam, T., Kim, M.H., 2016. Numerical study on thermal hydraulic performance improvement in solar air heater duct with semi ellipse shaped obstacles. Energy, Vol. 112, pp. 588-598.


7. Kumar, A., Kumar, R., Maithani, R., Chauhan, R., Sethi, M., Kumari, A., Kumar, S., Kumar, S., 2017. Correlation development for Nusselt number and friction factor of a multiple type V-pattern dimpled obstacles solar air passage. Renewable Energy, Vol. 109, pp.  461-479.


8. Nadda, R., Kumar, A., Maithani, R., 2017. Developing heat transfer and friction loss in an impingement jets solar air heater with multiple arc protrusion obstacles. Solar Energy, Vol. 158, pp. 117–131.


9. Bensaci, C., Moummi, A., Flor, F., Jara, E., Rincon-Casado, A.,  Ruiz-Pardo, A., 2020. Numerical and experimental study of the heat transfer and hydraulic performance of solar air heaters with different baffle positions. Renewable Energy, Vol. 155, pp. 1231-1244.


10. Luan, N.T., Phu, N.M., 2020. Thermohydraulic correlations and exergy analysis of a solar air heater duct with inclined baffles. Case Studies in Thermal Engineering, Vol. 21, 100672.


11. Sharma, N.Y., Madhwesh, N., Karanth, K.V., 2019. The Effect of Flow Obstacles of Different Shapes for Generating Turbulent Flow for Improved Performance of the Solar Air Heater. Procedia Manufacturing Vol. 35, pp. 1096-1101.


12. Saravanakumar, P.T., Somasundaram, D., Matheswaran, M.M., 2019. Thermal and thermo-hydraulic analysis of arc shaped rib roughened solar air heater integrated with fins and baffles. Solar Energy, Vol. 180, pp. 360-371.


13. Saravanakumar, P.T., Somasundaram, D., Matheswaran, M.M., 2020. Exergetic investigation and optimization of arc shaped rib roughened solar air heater integrated with fins and baffles. Applied Thermal Engineering, Vol. 175, 115316.


14. Kumar, A. and Layek, A., 2021. Energetic and exergetic based performance evaluation of solar air heater having winglet type roughneѕѕ on absorber surface. Solar Energy Materials and Solar Cells, Vol. 230, 11147.


15. Saravanan, A., Murugan, M., Sreenivasa Reddy, M., Ranjit, P.S., Elumalai, P.V., Pramad Kumar, Rama Sree, S., 2021. Thermo-hydraulic performance of a solar air heater with staggered C-shape finned absorber plate. International Journal of Thermal Sciences, Vol. 168, 107068.


16. Dong. Z., Liu. P., Xiao. H., Liu, Z., Liu. W., 2021. A study on hear transfer enhancement for solar air heaters with ripple surface. Renewable Energy, Vol. 172, pp. 477-487.


17. Sureandhar, G., Srinivasan, G., Muthkumar, P., Senthilmurugan, S., 2021. Performance Analysis of arc rib fin embedded in a solar air heater. Thermal Science and Engineering Progress, Vol. 23, 100891.


18. KhoshAkhlagh, F., Molaei Pardeh, A., Abadijoo, M.M., 2014. Analysis and zoning of climatic potentials of Khuzestan province for the use of solar energy. Nivar, Vol. 92. (In Persian)


19. K. Mohammadi, M. Sabzpooshani, Comprehensive performance evaluation and parametric studies of single pass solar air heater with fins and baffles attached over the absorber plate, Energy, Vol. 57, pp. 741-750, 2013.


20. MK. Gupta, SC. Kaushik. Performance evaluation of solar air heater for various artificial roughness geometries based on energy, effective and exergy efficiencies. Renew Energy, Vol. 34, pp. 465-476, 2009.

21. Ansari, M. and Bazargan, M., 2018. Optimization of Flat Plate Solar Air Heaters with Ribbed Surfaces. Applied Thermal Engineering, Vol. 136: pp. 356-363.