Environmental and energy analysis for photovoltaic-thermoelectric solar unit in existence of nanofluid cooling reporting CO₂ emission reduction

Background: It is crucial to introduce new strategies to intensify the efficiency of photovoltaic thermal (PVT) unit. The incorporation of a thermoelectric generator (TEG) within a solar unit can notably improve its electrical performance. Additionally, modifying the properties of the cooling fluid by incorporating nano-powders proves to be an effective approach in optimizing PVT systems. Methods: This study delves into an inventive design for a PVT unit, exploring novel techniques to boost its performance. To enhance the cooling of the PV component, two strategies were employed: 1) the implementation of a new-style turbulator, and 2) the integration of confined jets. Thus, three cases were simulated: case 1 (without any enhancement), case 2 (with the turbulator), and case 3 (employing both techniques). Additionally, the TEG layer was incorporated with the PV layers to augment overall efficiency. The testing fluid, water, was infused with SiO2 nanoparticles, and their properties were determined using a homogeneous mixture formulation. For simulating the current 3D model, the Finite Volume Method was chosen, accounting for laminar flow in fluid zones and applying the pure conduction equation for solid zones. The impacts of altering geometry, heat flux (G), inlet velocity within the tube (V-i), and jet (V-j) on performance metrics (including PV electrical (eta(PV)), thermoelectric (eta(TE)), thermal (eta(th)), overall electrical (eta(El)), total (eta(Tot))) have been detailed in the results section. Significant findings: By implementing two cooling techniques, the uniformity of panel temperature experiences a notable enhancement of about 79.96 %. With an increase in the velocity of the nanofluid within the tube, there is an approximately 1.99 % improvement in the value of eta(Tot). Furthermore, when V-i=0.08 m/s, the values of eta(El), and eta(Tot) see an increase of about 3.09 % and 12.59 %, respectively, upon the installation of the jet and turbulator. An augmentation in G leads to a rise in eta(Tot) by approximately 5.32 % and 7.32 % for cases 1 and 3, respectively. When G = 810 W/m(2), incorporating a jet and turbulator in the PVT system results in improvements of about 2.64 % in eta(El), and 10.45 % in eta(Tot). The increment of eta(Tot) with switching from case 1 to case 3 enhances about 24.62 % with the rise of G. Moreover, as the inlet velocity of the jet increases, the values of eta(TE), eta(th), and eta(Tot) enhance by about 3.43 %, 1.87 %, and 1.06 %, respectively.