Thermal- hydraulic performance optimization of PV panel cooling via aluminum - Modified ground heat exchanger under Iraqi climate conditions

Photovoltaic (PV) systems operate more inefficiently at higher temperatures due to the high level of solar irradiance. In the current study, using ground heat exchangers (GHEs) is investigated as a strategy to reduce the temperature of PV panel surfaces and enhance the efficiency of PV panels. The limitation of this approach lies in the limited heat transfer ability of the soil surrounding the ground heat exchangers (GHEs), due to the low thermal conductivity of natural soil. To address this shortcoming, the thermal conductivity of the soil can be enhanced by adding powdered aluminium (Al) to improve its thermo-conductivity properties, as aluminium exhibits excellent thermo-conductivity qualities. The authors investigated various ratios of aluminium mixing, ranging from 10 % to 30 %. ANSYS Fluent was used to run the simulation of the typical summer conditions in Iraq with solar irradiance varying between 200 W/m² and 1000 W/m², ambient temperature between 30 °C and 48 °C and mass flow ranges varying between 0.005 and 0.02 kg/s developed five flows scenarios. Evaluation of each case was done between 8.00 and 17.00 to capture the PV performance in a day, to identify the impact on surface temperature, electrical efficiency, pumping power, and thermal-hydraulic performance factor (THPF). This investigation examined the performance comparison between aluminium-enhanced GHE systems and those of uncooled PV panels, water-spray-cooled panels (PV-W), standard GHEs (PV-GHE), and modified systems with varying aluminium contents (PV-GHE-AL). In PV-GHE-AL-30 %, the highest cooling system thermal efficiency was achieved, along with the lowest thermal surface temperature of 44 °C, compared to the reference PV panel at 1000 W/m², coupled with a 22.7 % higher electrical efficiency. The findings confirm that aluminium powder is effective in enhancing the soil performance of photovoltaic cooling systems using GHE technology at a constant drop in pressure.