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An artificial neural network (ANN) model was developed to simulate the convective drying process of watermelon rind pomace used in the fabrication of non-traditional flour. Also, the drying curves obtained experimentally were fitted with eleven different empirical models to compare both modeling approaches. Lastly, to reduce the required fossil fuel in the convective drying process, two types of solar air heaters (SAH) were presented and experimentally evaluated. The optimization of the ANN by a genetic algorithm (GA) resulted in an optimal number of neurons of nine (9) for the first hidden layer and ten (10) for the second hidden layer. Also, the ANN performed better than the best fitted empirical model. Simulations with the trained ANN showed very promising generalization capabilities. The type II SAH showed the best performance and the highest air temperature it reached was 45 °C. The specific energy consumption (SEC) needed to dry the watermelon rind at this temperature and the CO 2 emissions were 609 kWh.kg -1 and 318 kg CO 2 .kWh -1 , respectively. Using the type II SAH, this energy amount would be saved without CO 2 emissions. To reach higher drying temperatures the combination of the SAH and the electrical convective dryer is possible., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Onion is a commonly used vegetable in the Cuyo Region, Argentina, and important in the world global vegetable production ranking. Production levels often exceed immediate markets of fresh sale, and excesses, although still edible, are currently discarded (mostly incinerated and disposed in landfill, creating numerous environmental hazards). To minimize these adverse environmental problems, this research investigates upgrading the discarded products by dehydration, hence guaranteeing their ultimate food-use. The dehydration process of discarded onion cv. Crioula Roxa was hence studied at 60 and 70 °C, temperatures selected to maintain the main physicochemical characteristics of the onions, while also creating optimum heat and mass transfer coefficients while significantly reducing the energy consumption and CO 2 emissions. When using an electrically-heated convective dryer, the Specific Energy Consumption (SEC) values and the CO 2 emissions during dehydration at 70 °C are 738.89 kWh.kg -1 and 264.74 kg of CO 2 kg -1 , respectively. These values are only 41.61 kWh.kg -1 and 2-4 kg of CO 2 kg -1 if a solar dryer is applied. The thermal diffusivities were 1.86✕10 -10  m 2  s -1 (dehydration) and 1.08✕10 -10  m 2  s -1 (rehydration), showing a weak effect of the dehydration process on the solid structure and properties., (Copyright © 2020 Elsevier Ltd. All rights reserved.)