Design of Hazelnut Drying System Supported By Solar Energy, Investigation of Drying Performance and Determination of Proper Drying Model

Rapid and efficient drying process for the hazelnuts is required because of the lack of plain areas for flat drying due to the rough landforms in the Black Sea Region, high amount of cloudy days, causing product deteriorations and rots by instantaneous rain transitions and unexpected sudden rains. In this study, a hazelnut drying system supported by solar energy in order to achieve a rapid and efficient drying process was designed and drying performance was examined. In the designed system, a spiral shaft was used for movements of the hazelnuts in the drying chamber. Besides, the inner temperature of the chamber increased with the help of a sun collector. The process control device was used to keep the inner temperature as constant at 40°C. In the experiments, 20kg weight hazelnut husk was used. The experiments were performed between 09:00 and 17:00 hours in a day and the total drying process took about 8 hours. The moisture ratios (MR) and drying rates (DR) graphics were obtained by scaling weight losses of the hazelnuts in each hour. As a result, it is observed that the 20kg weight of the hazelnuts decreased to the 17.201kg and therewith the total removed moisture from the hazelnuts was about 2.799kg. In the light of the moisture ratios obtained by experiments, 8 different kinetic drying models were performed with MATLAB software. According to the kinetic model results, the lowest reduced chi-square (χ 2 ) and root mean square error (RMSE) were about 241x10 -6 and 155x10 -4 respectively. In addition, the coefficient of determination (R 2 ) was calculated as 0.9982 which is the highest result closest to 1. Among the 8 kinetic models, the Page model is given the best results for the drying process.