Development and performance comparison of mixed-mode solar crop dryers with and without thermal storage

The major shortcoming of multiple trays cabinet dryer is uneven drying of the products being dried on different trays. Mixed-mode solar crop dryers with and without thermal storage materials were developed and tested under the same meteorological conditions of Zaria, Nigeria. The dimensions of the dryers were: 0.65 m, 0.30 m(2), 0.9 m, 0.7 m, 1.64 m and 0.43 m for collector length, collector area, the height of the drying chamber, chimney height, length of the drying chamber and width of the drying chamber respectively. It was observed that the average drying rates, collector efficiencies, and drying efficiencies of the solar crop dryers with and without thermal storage for June and August 2016 test period are 2.71 x 10(-5) kg/s and 2.35 x 10(-5) kg/s, 67.25% and 40.10%, 28.75% and 24.20% respectively. As per the experimental results, the efficiency of the dryer with the storage materials is enhanced by about 13% due to the thermal storage used. The extent of the variation of the drying products on different trays was investigated using statistical t-test analysis. The p-values obtained revealed that there was no significant difference between the drying rates of the yam slices on different positions of the trays. (C) 2018 Elsevier Ltd. All rights reserved.