Improving the Dryer Performance and Energy Efficiency Behavior of Hybrid Solar Thermal Dryer Compounding With Phase Change Material

Abstract The flat plate collector (FPC) featuring nanofluid has high heat absorption, better thermal conductivity, and a superior heat transfer coefficient. However, poor nanofluid stability, fluctuations in solar radiation, and thermal loss, which can significantly influence the thermal performance of the FPC. This research aims to overcome the difficulties with the conventional system and enrich the heat storage and thermal performance of the FPC-driven solar dryer, combining it with RT50 phase change material and different volume concentrations of hybrid nanofluid (HNF) (silica and multiwalled carbon nanotubes). Moreover, the stability of HNF was evaluated via a zeta potential stability test, and the combined actions on specific heat capacity, thermal conductivity, heat transfer coefficient, dryer rate, energy efficiency, and heat storage properties were evaluated and compared with the base fluid. Zeta potential test showed better thermal stability and the setup operating with 1.5 vol% of HNF exhibited better specific heat capacity (4430.9 J/kg K), improved thermal conductivity (0.945 W/m K), a high heat transfer coefficient (849.7 W/m2 K), superior latent heat storage (310.4 kJ), and a better drying rate (0.39 kg/h) with minimized dryer duration (43 min) and improved thermal efficiency of 67.4%.