This study examines the heat and mass transfer coefficient, thermal effusivity, and other thermal properties of solar-dried cocoyam chips, as well as the drying kinetics. The research also assessed the economics of the solar dryer. For these reasons, a solar dryer with a partitioned collector was developed that creates a double airflow travel distance to delay the airflow inside the collector. The partitioning of the collector delays the airflow and helps to create more turbulence for the airflow with increased energy. The solar dryer was locally developed at the Michael Okpara University of Agriculture and tested during the humid crop harvesting period of September for the worst-case scenario. The obtained drying curves and kinetics for cocoyam drying are subjected to the vagaries of weather conditions. The drying rate showed declining sinusoidal characteristics and took about 25 h to attain equilibrium. Analysis of the airflow velocity showed gravitation between laminar and turbulent flow, ranging from 171.69 to 5152.77. Specific heat capacity, thermal conductivity, and effusivity declined with moisture content while the thermal diffusivity increased. However, the values of thermal effusivity ranged from 12.2 to 47.94 W·s^1/2·m⁻²·K⁻¹, which is within the range of values for insulators. The heat and mass transfer coefficient varied as a function of the airflow velocity. Fitting the drying curve into semi-empirical models showed that the two-term model was the best-fitted model for the experimental data from drying cocoyam. Using the solar dryer in Nigeria can save $188.63–$1886.13 in running costs with a payback period of 0.059–0.59 years (21.54–215.35 days) at a rate of 10–100% of usage.

This study evaluates a solar PV-powered evaporative cooling system for vegetable cooling. The system features dual cooling chambers with two different biomass pads, operating at different temperatures. To assess its potential, the research examines the evolution of temperature and humidity of the cooling chamber, evaporative effectiveness, cooling capacity, coefficient of performance (COP), energy metrics, greenhouse gas emissions, and overall cost. The results show that the system achieved a temperature depression range of 0.22 to 5.2 °C and 0.57 to 10.94 °C for wood shavings and polyurethane foam, respectively, under no-load conditions, while the values were 0.79 to 4.7 °C and 1.22 to 9.88 °C, with average values of 3.09 and 7.0 °C, for the same materials under loaded conditions. Loaded conditions also yielded a cooling capacity of 5.7 to 33.93 W for wood shavings and 8.13 to 75.55 W for polyurethane foam. The cooling efficiency ranged from 19.9 to 96.42% for polyurethane foam and 3.62 to 60% for wood shavings. The system’s COP was higher than that of solar-powered mechanical chillers, ranging from 2.37 to 22.92. The energy production factor was 2.3 to 2.4, with a lifecycle conversion efficiency of 0.5 and an energy payback time of 1.1 and 2.2 years for using polyurethane foam and wood shavings, respectively. The net present value was positive, and the levelized cost of energy was low, at 36.7 to 38.3 NGN/kWh (0.043–0.045 USD/kWh), making it a viable alternative to grid-based energy systems in Nigeria. Additionally, the system offers significant CO₂ mitigation potential, with estimated carbon credits of NGN 65,059 (USD 71.56) and NGN 98,576.49 (USD 108.43) over its lifetime.