الفهرس 
Solar Air Heaters (SAHs)
EXPERIMENTAL SETUP AND EQUIPMENTOnly 14 pages are availabe for public view
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Abstract
Enhancing the thermo-hydraulic performance of solar air collectors (SACs) can be achieved by various ways, some of which are; fins, ribs, baffles, porous medium and groves. So far, diverse attempts have been established to enquire the effects of these ways on the heater performance. Consequently the performance of a single pass SAC (SPSAH) employing Porous Medium (PM) with various density and porosity has been experimentally investigated. Several porous packings made of compressed aluminum scraps with different packing density and filament size were utilized. A SAC fitted with a solar simulator was designed to apply a uniform heat flux (q”) of about 700 W/m2, where the solar simulator generates irradiance similar to that coming from the sun. It is utilized to run experiments under constant heat flux conditions without the demand for natural solar radiation. Noting that solar simulator utilized in this study is designed and constructed of scrape which is mentioned in details. The distribution of the flux generated from the constructed solar simulator was measured and reported in the results.
This study aims to improve the temperature lift in an SPSAH with a minimum possible increase in pressure DROP (ΔP). Locally available metal packings are used as a PM to accomplish this aim. Two types of packing are employed in experimental work. The first type is made of compressed aluminum swarf with different wire size and packing density. The porosity in this type ranges from 0.60 to 0.96. The second type is made of packed steel wire mesh with varied mesh density. The porosity of this second type ranges from 0.60 to 0.92.
The thermal efficiency (ηth) is used to evaluate the heater performance. The pressure drops (ΔP) associated with each packing is employed to assess the exergy loss from the solar heater, and the packing is compared accordingly. Additionally, a Computational Fluid Dynamic (CFD) analysis is executed to analyze the SPSAH performance.
The results illustrate that employing compressed aluminum swarf as a porous medium increases the thermal efficiency (ηth) of SPSAH and preserves the temperature inside the heater for longer running periods. Additionally, the results indicate that increasing the air mass flow rate (m ̇) will decrease the temperature difference (ΔT) between the inlet and the exit sections of the heater, but also, will cause an increasing in ηth of the system.
The packed SPSAH (packed with aluminum swarf) enhanced the ηth by 50 - 60% compared to empty SPSAH for the same dimensions and air mass flow rate. The maximum temperature incurred from the packed SPSAH is 62 οC for a temperature difference of 34 οC. The experimental data validated the CFD results with a maximum deviation between both results within ± 2%.