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Drying Experiment of Rubber Sheet Using Solar Dryer with Solar Collector Installed on Top Wall of the Dryer

This research aims to study the efficiency of rubber sheet drying using a solar dryer with a top-tier solar collector. Drying conditions were separated into 3 phases. In the first phase (first day), the air velocity in the drying room was controlled at 0.2 m/s with 550 cm open ventilation area. In the second phase, (2–5 day), the subjects was exposed to air velocity of 0.2 m/s with 275 cm open-area ventilation. In the final phase (6–8 day), the air velocity was controlled at 0.1 m/s with the ventilation opening area of 110 cm. It can be seen that the ventilation opening area and the air velocity had an effect on the drying temperature control within the solar dryer. In the first phase, the average drying temperature was 40°C with average relative humidity of 38%. It increased to 48°C while the average relative humidity decreased to 25% in the second phase. At the final phase, the average drying temperature and the average relative humidity were 54°C and 18% respectively; at the average ambient temperature of 31°C, at the average relative humidity of 46% and the average solar radiation of 708 W/m. The mathematical models of moisture ratio for thin-layer drying (Newton, Page and Henderson and Pabis) were applied for the verification of results. It was found that Page model is more consistent than Newton and Henderson and Pabis model with R of 0.9825–0.9841, Adjusted R of 0.9822–0.9837, SSE of 0.04347–0.04918 and RMSE of 0.03074–0.0327 for rubber sheet dried with the solar dryer. In addition, for shade drying, the statistical parameters of Page model are R of 0.9672-0.9826, Adjusted R of 0.9665-0.9823, SSE of 0.03055–0.06592 and RMSE of 0.02577–0.03786.