Experimental Study on Tomato Drying Using a Solar Dryer Integrated with Reflectors and Phase Change Material

Fruits and vegetables are necessary for the humankind since they provide vitamins, minerals, starches, fiber, protein and a small amount of fat. As their production is seasonal, they should be stored during the non-productive seasons through drying process. Various techniques have been used for drying agricultural products; however, the most efficient, cost-effective and enviro-friendly technique is the utilization of solar energy via solar dryers. However, solar dryers suffer mainly from intermittent solar radiation and slow drying rate. Therefore, this paper presents an experimental study on the solar drying of tomatoes using forced convection (active) solar dryer integrated with reflectors and phase change material (PCM) heat storage under climate conditions of Khartoum, Sudan. The experiments were conducted on four modes; indirect solar dryer (Mode 1), mixed solar dryer (Mode 2), mixed solar dryer with PCM (Mode 3), and mixed solar dryer with PCM and reflectors (Mode 4). The results showed that the time required to completely dry the tomatoes was 10 h, 9 h, 7 h and 6 h for Modes 1, 2, 3 and 4, respectively. Mode 4 showed the best drying performance among the other modes, which could improve the drying rate of Modes 1, 2 and 3 by 39.4%, 32% and 8.2%, respectively.