تطوير مجفف بمصدري طاقة متجددة وجودة الأغذية المجففة به

Abstract

The present study was conducted in order to development and test a dual source solar dryer in the shape of a truss for drying some agricultural crops, including figs and strawberries, by using solar cells, and a source of illumination. Furthermore, in comparison, the dryer was tested without a solar cell, and the results were compared to each other and also compared with those of another (half-inclined) solar dryer, as well as an electrical dehydrator. The double-walled solar dryer consisted of a wooden frame painted black to increase the rate of solar radiation absorption inside the dryer; a double-wall made of transparent Lyxan polycarbonate with black thermal insulation placed in between; and two food trays with a wooden frame encasing black perforated plastic polypropylene that can withstand high temperature and is safe for food, as it does not react nor stick to dried food. There is also a wire screen to prevent the entry of insects through the vents; a filter to purify the air inside the dryer; a black solar collector; a fan; a solar cell to run the fan, an electrical inverter; and a lightbulb to provide heat. The results showed the following: 1. When drying figs and strawberries, the temperature inside the dryer reached 70.1º and 64.1º; as compared with the temperature outside the dryer which reached 41.9º and 37.1º for the figs and strawberries, respectively. In other words, there were differences of 28.2º and 27º respectively between the temperatures inside and outside the dryer. 2. When the drying time increased, the air relative humidity decreased; and the rate of decrease for the air relative humidity was higher inside the dryer than outside it, as the percentage of moisture reached 10% and 41% inside the dryer at the end of the experiment for the figs and strawberries respectively as compared with the humidity percentages outside the dryer which were 21% and 52% for the figs and strawberries with differences of 11% and 11% in air humidity inside and outside the dryer respectively.