Experimental and Mathematical Models for Solar Air Collector with Energy Storage

Due to the electric energy shortage and demand, this study found that conventional energy techniques that contaminate the environment must be reduced. This study investigated the efficacy of a three-pass solar air collector (SAC) thru a storage unit bed experimentally and by mathematical modeling. In this study, four solar air collectors were employed, each of which was linked to a stone storage bed in succession. As a storage medium, various sized black stones with a high density were used (۲۶۶۰ kg/m۳). The experiments were done for the climate of Duhok city, Iraq, on clear and partly cloudy days for two random days (February and March ۲۰۲۲) at a constant air flow rate (۰.۰۵۴ kg/sec). After sundown, stone storage bed maintained a temperature differential of around ۱۰°C for approximately ۵ hours, according to the collected data. In addition to being readily available and inexpensive, a used stone bed may retain heat for a long period after sunset, which is then released at night or on partly overcast days. A mathematical model of the storage bed system was used. It had been postulated that each stone within the storage bed could be considered a spherical, disc, or ellipse. The model takes into account physical properties as well as stone circumference, surface area, void fraction, temperature difference, and air mass flow rate. The equations were solved using an iterative method and implemented using MATLAB R۲۰۲۰b software. It was found that the spherical stone has a good ability to gain heat, compared to the other two forms.

Keywords:

Solar Air Collector (SAC) , Stone Storage bed , Energy Storage , Stone (rock).