Experimental Investigation of the Effect of Heat Pipe Tilting on a Concentrated Photovoltaic/Heat Pipe Passive Cooling System

To maintain the concentrated photovoltaic systems (CPV) output, effective cooling is necessary. In contrast to costly and complicated active cooling methods, passive cooling is static, simple, and maintenance-free. Among passive techniques, Heat Pipes (HPs) are devices that efficiently transfer heat from the evaporator to the condenser. The inclination angle of wicked, liquid-filled HP's long-axis determines how well it cools, as an effect of the gravitational force acting on the condensed liquid. This study investigates the effect of tilting the HP long-axis on the performance of the different parameters of the CPV, which is passively cooled by thermal attachment to its back side. Two similar HPs except for their lengths were attached alternatively. Different concentrated illumination levels are then allowed to be incident on the CPV. At each illumination level, the inclination of the HP long-axis was varied from -90 deg (completely vertical with condenser up) to 90 deg (completely vertical with condenser down), passing through 0 deg (HP is completely horizontal) with a step of 15 deg. The effect of such variations on the inclinations has been tested on the two systems. The system incorporating the long HP was found to have a higher cooling performance at an angle of -15 deg, compared to the short HP system, which has its highest cooling capacity at an angle of -60 deg, with an increase of about 7% for the maximum power in case of using the former system compared to the latter.