COMPUTATIONAL FLUID DYNAMICS AND PERFORMANCE EVALUATION OF A CHIMNEY SOLAR DRYER FOR CHILLI PEPPER

Abstract

The postharvest losses of agricultural produce in Ghana and other developing countries is high. Efforts to promote shelf-life extension of the fresh produce is centred around temperature and moisture management. Moisture control by drying is suited to a number of crops as it inhibits microbial decay and physiological processes of deterioration. However, there are often inefficient drying infrastructure in developing countries. Thus, the focus of this research was to structurally modify a chimney solar dryer originally designed by the Horticulture Innovation Laboratory of the University of California, Davis and include sea pebbles in the collector base to enhance its heating system and drying performance.  A computational fluid dynamics analysis using ANSYS Fluent was used to assess the functional parameters such as the airflow, temperature and relative humidity. Subsequently, the performance of the modified dryer was compared with the original design using chilli pepper (Capsicum annuum ) as the test product. The results showed a strong correlation between the simulated and no-load experimental conditions in terms of temperature (R= 0.987) and relative humidity (R = 0.927). The presence of sea pebbles improved the drying rate, reduced the moisture content of the chilli from 73.12 % to 7.15%  (w.b.) in 36 h, while the dryer without sea pebbles dried the chilli from 73.13% to 9.67% (w.b.) within the same period. Overall, the inclusion of sea pebbles and the minor structural modification enhanced the drying performance of the chimney solar dryer.