Modeling of thermoelectric generator combined with solar system including paraffin with ternary nanoparticles

This article introduces an innovative integration of a thermoelectric generator (TEG) module with a U-tube evacuated solar system, using paraffin as the phase change material (PCM). To enhance the PCM's melting rate and improve the system’s overall thermal efficiency, three advanced strategies were employed: (1) The addition of ternary nanoparticles—comprising MgO, ZnO, and MWCNT—into the paraffin to boost thermal conductivity; (2) Modification of the U-tube's geometry from a circular to a three-lobed design for improved heat transfer; and (3) The installation of tree-shaped fins to optimize heat distribution and accelerate the melting rate. The unsteady thermal behavior has been modeled using the finite volume method. The results demonstrated that these techniques significantly increased the melting rate and thermal efficiency, though they led to a slight decrease in the TEG's electrical power output. Four configurations were examined: (Case 1: Circular U-tube with pure paraffin; Case 2: Three-lobed U-tube with pure paraffin; Case 3: Three-lobed U-tube with ternary nanofluid; Case 4: Three-lobed U-tube with ternary nanofluid and tree-shaped fins). The incorporation of ternary nanoparticles accelerated the melting process, increasing the charging rate by 3.47 % at 150 s and 1.92 % at 450 s. Replacing the circular U-tube with a three-lobed design, combined with ternary nanomaterials, improved the liquid fraction by 57.76 % at 150 s and 22.28 % at 450 s. When all three techniques were applied together, the temperature of the system rose by 6.14 % at 150 s and 4.57 % at 450 s. However, in case 4, a decrease of 3.23 % in the TEG’s efficiency was observed at 900 s, yielding an electrical output of 2.28 kW.