الفهرس 
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Abstract
The main objective of this study was to exploit one of the renewable energy sources, which is solar energy in solar drying tomato fruit (Solanum lycopersicum L.) and turning it into tomato powder. The tomato is the most significant horticultural crop in Egypt. Egypt is the fifth largest producer of tomatoes in the world. However, the tomato yield is subjecting to loss during harvesting and production, as a result, one technical way to reduce losses in this critical crop is to dry the tomatoes.Two different architectural forms of solar dryers (lean-to and curved lean-to greenhouse solar dryer) and compare these solar dryers with the natural sun drying. Each tomato fruit with an initial moisture content of 92.50%w.b. (±0.77w.b.) was cut into two halves and treated with (5%) sodium chloride. After this treatment the primary moisture content was 91.52%w.b. (±0.98 w.b.) The thermal performance analysis of the two solar dryers and the drying properties of the thin layer of tomato fruits were tested and evaluated. The main obtained results showed that, the hourly average useful heat energy gain for the lean-to solar dehydrator was 743.2 Watt of which 168.2 Watt was used to evaporate water from the fresh yield during the drying process (68 h). As a result, the overall efficiency in evaporating water from the fresh tomato for the lean-to solar dryer was 22.63%. While the hourly average useful heat energy gain for the curved lean-to solar dehydrator was 675.8 Watt of which 138.3 Watt was used to evaporate water from the fresh yield during the drying process (95 h). Consequently, the overall efficiency in evaporating water from the fresh yield for the curved lean-to solar dryer was 20.46%. The final moisture content of dried tomato fruits was reduced to 7%w.b. (±0.72w.b.) An attempt was made to investigate the behavior of dried tomato fruits in a thin film using solar energy by running two analytical models (Lewis model and Henderson and pabis models). The Lewis model had the highest coefficient of determination (R2) values and the lowest standard error (SE) values. In addition, the effect of the drying process on the four different physical and chemical components (nitrogen, ash, lycopene and ascorbic acid) were measured before and after the drying process for the three different transactions of the drying process. The obtained results at the end of the drying process showed that drying tomato fruits using solar dryers is better than the natural sun drying. It also indicated that the lean-to solar dryer gave better results than the curved lean-to solar dryer.