Fabrication and Evaluation of a Solar Dryer Made From Twin-Wall Clear Polycarbonate Sheets

Abstract

This study evaluated the newly designed and fabricated solar dryer based form the following design criteria 1) made of locally available materials, 2) easy to maintain and low maintenance cost, 3) portable, 4) products to be dried should not be exposed to rain and foreign elements (should be clean), and 5) able to dry faster than sun drying method. A solar dryer was fabricated and made mainly of twin-wall polycarbonate sheets with angle bar framing, with 3 layers of removable aluminum screen trays with aluminum framing. It has 3 solar heat collectors that provided additional heat to the drying chambers. Results of the evaluation showed that the maximum average drying temperature attained in the chambers of the solar dryer was 67.6⁰C or an increase of 32.2⁰C from the average highest average outside temperature of 35.4⁰C. When the solar heat collectors were removed, the solar dryer was able to attain an average maximum temperature of 57.5⁰C or an increase of 24.5⁰C from an average outside temperature of 33.0⁰C. When evaluated to dry fresh saluyot (Corchorus olitorius L) leaves (Initial MC of 89.58%) and sweetpotato (Ipomoea batatas Lam) tops (Initial MC of 94.50%), the solar dryer in 2.33 hours reduced the moisture content, wet basis, of the to an average saluyot of 26.54% as compared to the sun drying method which reduced it to an average of 47.14% The performance of the dryer will be evaluated further using other available products in the uplands.