Experimental and Numerical Investigation of Thermal Behavior of a Novel Cylindrical Solar Collector with the Utility of a Phase Change Material

In this paper, an experimental and numerical investigation of the thermal behavior of a novel solar collector was performed. This last one is cylindrically shaped and comprises four layers: Pebble layer, phase change material (PCM) layer and two air layers separated by a plastic cover layer. The motivation for selecting four layers is to reduce the heat loss caused by the continuous convection heat transfer. The experimental solar collector was thermally insulated and covered with a plastic cover at the top. The experimental setup was built and operated in an arid area at the University of Thi-Qar in the city of Nasiriya in Iraq for 20 days (from 10 November 2022 to 30 November 2022). During this period, layer temperatures were measured using K-type thermocouples. A numerical model was developed based on the energy balance of each solar collector layer; the forward Euler method and MATLAB computational program were utilized to solve the formed equations. Comparisons between experimental and numerical results showed acceptable agreements with relative errors of 1.81%, 3.21% and 3.68% for the first air layer, second air layer and PCM layer, respectively. After the model validation, the numerical model was used to simulate the thermal behavior of the solar collector during the whole year of 2022. The results showed that the temperature varies from −2 °C to about 66 °C during the year, with a difference of 15.52 °C in July and around 6.84 °C in December. Additionally, the temperature of PCM reached a maximum of around 63 °C in June and over 54 °C in the same month for the pebble layer.