Enhancement in the electrical efficiency of a photovoltaic thermal system through ternary nanofluids application: Nanomaterial shape effects and phase change material encased in a rectangular block

This research investigates the enhancement of electrical efficiency in a photovoltaic thermal (PV/T) system by utilizing water-based ternary hybrid nanofluids and incorporating a phase change material (PCM) within the flow channel. The system comprises a glass cover, a silicon layer, and a copper absorber, beneath which a flow channel contains a block filled with Paraffin Octadecane Wax (C18H38) as the PCM. The analysis is conducted using COMSOL Multiphysics 6.0, applying a conjugate heat transfer interface to simulate the interaction between conduction and forced convection within the solid and liquid domains. The study explores the phase transition behavior of the PCM, the thermal dynamics, and the electrical efficiency of the PV/T system under varying Reynolds numbers (50 to 150) and different nanomaterial shapes, including spherical, bricks, cylindrical, platelets, and blades. The simulations consider equal volume fractions of copper, alumina, and multi-walled carbon nanotubes (MWCNT) in the nanofluid, with total volume fractions ranging from 1 % to 10 %. Results reveal that blade-shaped nanoparticles significantly enhance the phase transition rate of paraffin, achieving an average phase transition of 81.97 % at Reynolds number 50 and 10 % volume fraction. Furthermore, the temperature variation along the PCM block shows rapid behavior with blade-shaped particles. Optimal electrical efficiency, reaching a peak of 9.42 %, is observed at Reynolds number 150 and 10 % volume fraction with blade-shaped nanoparticles. The study underscores the importance of nanoparticle shape and volume fraction in improving PV/T system performance. The findings recommend blade-shaped nanoparticles and higher nanofluid volume fractions to maximize electrical efficiency. This work provides valuable insights into the potential of ternary hybrid nanofluids and phase change materials for advancing PV/T technology.