Computational performance of the ISD solar energy system was evaluated using MATLAB Simulink. To handle the drying of lightweight materials, modification was made by adding an air deflector and trays inside the ISD. The technical performance of an inflatable solar dryer (ISD) to dry amaranth leaves (Amaranthus spp.) was investigated. A strategy for the early detection of aflatoxins in maize is recommended to avoid contaminated maize in the food chain. Although the drying performance in terms of drying time and product quality regarding colour, yeast, and mould was similar for both drying methods, the advantage of ISD in reducing the risk of spoilage due to sudden rain is obvious.
In one of the received maize lots that was already heavily contaminated after harvest, drying with DSD and ISD reduced the aflatoxin content from 569.6 µg kg−1 to 345.5 µg kg−1 and 299.2 µg kg−1, respectively. Maize was dried using both methods to a moisture content below 14% after two days. The maximum temperature inside the ISD reached 63.7 ☌ and averaged 7 ☌ higher than the ambient temperature. In this study, the drying performance of an inflatable solar dryer (ISD) was compared to direct sun drying (DSD) in Gombe Town, Wakiso District (Uganda) by analysing the moisture content, yeasts, moulds, aflatoxin, and colour. The traditional drying of maize in the open sun is prone to adverse weather and extraneous contamination. Maize is an important staple in Africa, which necessitates immediate drying to preserve the postharvest quality. The proposed dynamic model provides an efficient computational tool that can be applied to predict the drying performance and to optimize the ISD design. The simulated temperatures and moisture content in the ISD showed high accuracy (mean absolute percentage error (MAPE) < 10%) with the experimental data. The MATLAB/Simulink model was further used to predict the drying performance under various weather conditions spanning 10 years. Three batches of drying experiments were performed and airflow measurements were taken inside the dryer to validate the models. Moreover, a thermal model was developed in MATLAB/Simulink by taking into account heat transfer in the heating area and coupled heat and mass transfer within the drying area. To this end, the airflow behavior in the ISD was simulated using computational fluid dynamics (CFD) via ANSYS Fluent. Although the ISD was successfully tested with different agricultural products, further characterization of the ISD design is required for predicting the drying performance. Thus, the inflatable solar dryer (ISD) was developed through the collaboration of the University of Hohenheim, the International Rice Research Institute, and GrainPro Philippines Inc. In the Philippines, postharvest losses in rice production can reach about 36% in the drying process alone. Small-scale farmers in developing Asian countries have minimal agricultural mechanisms available to them. © 2017, Chinese Society of Agricultural Engineering. The ISD showed advantages over sun drying, despite longer drying periods. Quality was not found to be affected with respect to drying treatment. In both seasons, the final moisture content of 12% was reached after prolonged drying periods. Moisture content was reduced from 23% to 14% within 26-52 h of continuous operation during the rainy season and 16% to 14% within 4-26 h of drying during the dry season. Sun drying and shade drying were carried out in parallel for comparison and product was evaluated for moisture content and quality in terms of milling recovery and head rice yield. The ISD has been evaluated for paddy in the Philippines during both rainy and dry seasons and was subsequently optimized. During experiments, paddy was spread on the floor and mixed with a special roller bar. The tunnel does not need a substructure as it is stabilized adequately from pressure created by two axial flow ventilators. To reduce heat loss, a flexible multilayer floor was used along the drying area. To form a drying tunnel, transparent polyethylene (PE) film attaches by zipper to a reinforced black polyvinyl chloride (PVC) film. Due to the need for simple and economical technologies, an inflatable solar dryer (ISD) was developed based on adaptations of the Hohenheim-type solar tunnel dryer. For rice, grain moisture content of 14% prevents microbiological activity, while a level of about 12% minimizes quality losses over prolonged storage periods. Drying and storage of paddy are two key stages where management can be improved. Although considerable progress has been made with respect to improved breeds and production practices, losses during postharvest handling remain considerable. Rice is the staple food for more than three billion people worldwide.
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