Analytical study and fabrication of a solar-based dryer for pepper-drying (agricultural product drying)

Sarawak has fertile slopes and an optimum environment for pepper cultivation. The state produces the majority of pepper products in Malaysia and contributes to multimillion agricultural export earnings every year. The pepper cultivation in Sarawak relies on smallholdings and there were no large-scale plantation nor estate recorded so far. The majority of farmers exercise natural sun drying to produce the peppercorn as this method is simple to implement at low cost. However, it does not guarantee stable output quality and quantity due to unpredictable weather conditions and massive labour effort.

This report explores a workable passive solar dryer that will work well in tropical rainforest climate for local pepper smallholdings. It utilises existing technologies from different applications and optimise for small quantity peppercorn production. It also features low cost and sustainability. The dryer is simple to operate, mobile, requiring no artificial power assistance and is capable of drying peppercorns at targeted weather condition. The design of the solar dryer is based on pressure differential stack effect and fluid flow optimisation to ensure optimum condition in the drying chamber. The design was implemented and tested in open field for characteristics studies. Experiments done have shown the dryer will work satisfactorily in tropical climate from sunny days to mixed weather to rainy days and even on a cold wet night. Although some adjustments on the dryer (adjusting chimney height) are needed for different weather conditions, the dryer has, in general, given a satisfactory performance. It has proven to be able to boost the throughput with acceptable quality with the least possible human effort. The design has proven working for peppercorn production from this research; yet some modifications can be done to further enhance the achievement, it includes: weight reduction and heat flow optimisation at dryer inlet for more even drying.