Design of a Friendly Solar Food Dryer for Domestic Over-Production

Abstract

Solar drying is one of the many ways of efficiently making use of solar energy to meet the human demand for improved sustainability. In this study, we describe the construction and testing of two indirect solar dryer prototypes, especially designed for vegetables and fruits. The dryers had two compartments: a solar panel and a drying chamber. The dryers were mainly made of wood (Prototype 1) and styrofoam (Prototype 2) and both used recycled aluminum cans. The calculated yield of solar panels was 82% and 77% for Prototype 1 and 2, respectively. The drying tests performed with different fresh products showed that it was possible to dry all of them until less than 10% of their initial weight, at different times, depending on the type of product. As regards the apple slices, the solar dryers were able to remove 95.7% and 95.0% of initial moisture on a wet basis for Prototype 1 and 2, respectively. Comparative tests were conducted with an electric commercial dryer using the same product to explore the drying dynamics and costs. The cost of the final dry product, excluding the purchase of fresh goods, was 6.83 €/kg for the electric dryer, 1.78 €/kg for Prototype 1 and 1.72 €/kg for Prototype 2. Dehydrated apple slices are currently available on the market for around 34.50 €/kg. Our solar dryers can dry quality products at a very low cost for their entire life span, which allows them to compete with electric systems to prevent food waste in a cheaper and environmentally friendly way.

Development and evaluation of a hybrid smart solar dryer

“…As well as continued to decrease in weight at a significant rate over the next 4 h. Then the deterioration in weight occurred very slowly until the weight stabilized. As it recorded the lowest percentage decrease in weight in the last 2 h 0.4% and 1% for basil and sage, this is compatible with Chua et al., 2019, Fernandes et al., 2022, Hegde et al., 2015, Ibrahim et al., 2017, Zhu et al., 2021.…”

“…As well as continued to decrease in weight at a significant rate over the next 4 h. Then the deterioration in weight occurred very slowly until the weight stabilized. As it recorded the lowest percentage decrease in weight in the last 2 h 0.4% and 1% for basil and sage, this is compatible with Chua et al, 2019, Fernandes et al, 2022, Hegde et al, 2015, Ibrahim et al, 2017, Zhu et al, 2021 Drying rate is another significant factor for evaluating the drying process where the highest drying rates were achieved when using the HSSD at the highest temperature of 50, then 40, and finally 30 • C, as shown in Figure 8. However, the lowest rates of drying were recorded in the outdoor and indoor drying methods, respectively.…”

Thermal Performance of Dual-Operated Solar Cooking and Drying System

“…And after drying, it was found that the dual-operated solar cooking and drying system was able to dehydrate 89 % of moisture content, achieving a stable weight of 12 g after 8 hours of drying. See Figure 3.6 This result comes in consistence with a similar drying test which was conducted by (Fernandes et al, 2022) using sliced foods which include; apples, mushrooms, zucchini, lemon peel, sweet potatoes, and bananas. These sliced foods were dried to a moisture level of less than 10 % in less than 6 hours, necessitating only one drying day.…”

Effect of drying temperature and storage time on the crispiness of homemade apple snacks

“…The temperature promotes the diffusion of internal moisture towards the external surfaces of the apple slices, where it can be evaporated by the hot air flow. A different diffusion of moisture inside the apple slices of the two cultivars could explain this observation leading to a faster moisture loss from the ‘Royal Gala’ samples 31 …”

“…A different diffusion of moisture inside the apple slices of the two cultivars could explain this observation leading to a faster moisture loss from the 'Royal Gala' samples. 31 There does not appear to be a clear relationship between the amount of total soluble solids, the specific apple cultivar used, and the drying temperature. Other factors, such as the microstructure and composition of the apple slices, including their cellular arrangement and the presence of other components, may also influence the drying process and its effects on moisture removal.…”