Design and Experimental Study of an Indirect Forced Convection PV/T Solar Dryer in a Humid Tropical Zone

Abstract

Ginger is highly perishable because of its high moisture content, and conventional sun drying is often constrained by variable weather conditions, contamination, and prolonged drying periods. Indirect forced-convection photovoltaic/thermal solar dryers offer a promising approach by simultaneously supplying thermal and electrical energy for controlled drying in humid tropical environments. This study presents the design, construction, and experimental evaluation of an indirect forced-convection photovoltaic/thermal (PV/T) solar dryer for ginger under humid tropical conditions. The system integrates a 150 W PV module, an air-heating section, a drying chamber with three trays, and a fan powered by the photovoltaic component. Experiments were conducted using a 2 kg batch of ginger while monitoring solar irradiance, ambient and collector temperatures, relative humidity, air velocity, sample mass, and drying time. The influence of airflow was assessed at volumetric flow rates of 7, 5, and 3 m³/h, corresponding to air velocities of 2.8, 2.0, and 1.2 m/s, respectively. Lower airflow increased the temperature rise across the PV/T collector and improved thermal performance. At 1.2 m/s, the air-temperature increase between the collector inlet and outlet reached approximately 10°C, the maximum collector-outlet temperature was 54.2°C, the maximum PV-module surface temperature was 62.44°C, and thermal efficiency reached 18.28%. Ginger on the tray nearest the hot-air inlet reached the target moisture content after 380 minutes, whereas the upper tray required 620 minutes. The results show that airflow rate and tray position influenced heat transfer, drying rate, and drying time. The developed PV/T dryer provided simultaneous electrical and thermal energy for forced-convection drying, while the observed differences among trays indicate a need for improved airflow distribution.