جستجوی مقالات مرتبط با کلیدواژه "thin-layer" در نشریات گروه "مکانیزاسیون کشاورزی"

In this study, a pilot solar thin-layer dryer was designed and constructed. This dryer was equipped with an air-to-air cross-flow plate heat exchanger. An aluminum plate with a different design was used instead of holes in its surface. The collector, the airflow hitting the absorbent plate and passing through the surface of the pipes embedded on the absorbent plate received thermal energy and transferred it to the dryer chamber. Using the randomize complete design, influence of thickness of product in three levels of 3, 5 and 8 mm, three levels of air velocity of 0.5, 1 and 1.5 m/s and 2 modes with and without the use of heat exchanger on drying time of onion slices was studied. The crop thickness and airflow velocity had a significant effect on reducing the drying time of onion slices and the effect of crop thickness was greater than airflow velocity. However, the heat exchanger did not have a significant effect on drying time and collector efficiency.

fully instrumented air conditioning laboratory unit capable of controlling drying air temperature and humidity integrated with an instantaneous weighing thin layer drying system was used to investigate the thin layer drying behavior and desorption equilibrium moisture content of canola (Brassica napus L.).To this aim, freshly harvested canola samples with moisture content of about 12±0.5% (d.b.) were dried at temperature levels of 40, 45, 50, 55 °C and absolute air humidity levels of 0.005, 0.01, 0.015, and 0.02 Kg/Kg. The instantaneous grain moisture content was measured by weighing the sample periodically. Drying was continued until canola kernels reached a constant weight to obtain the hygroscopic equilibrium moisture for different combinations of drying air temperature and absolute humidity. To select a suitable model for describing the thin layer drying of canola, experimental drying data were fitted with three thin layer drying models,namely, Page, Modified Page and Two-Term Exponential models. Furthermore,four widely used desorption isotherm models including Chung-Pfost, Modified Chung–Pfost, Modified Oswin, and Modified Smith were used to fit the experimental data of equilibrium moisture content. Finally, non-linear regression analyses were run and based on the highest value for R2 and the lowest value for 2, mean bias error (MBE) and root mean square error (RMSE), the most suitable models for thin layer drying and equilibrium moisture content were determined to be Two-Term Exponential and Modified Smith, respectively.