The effect of microwave coupled hot air drying on rehydration ratio (RR) and total sugar content (TSC) of Chinese yam was investigated. Single factor test and response surface methodology were used for process parameter optimization with hot air temperature, hot air velocity, slice thickness, and microwave power density as variables and RR and TSC of dried products as responses. The effect of variables on RR followed the order: slice thickness > hot air temperature > microwave power density > hot air velocity. The effect of variables on TSC followed the order: slice thickness > microwave power density > hot air velocity > hot air temperature. The optimized process parameters were hot air velocity of 2.5 m/s, hot air temperature of 61.7 °C, slice thickness of 8.5 mm, and microwave power density of 5.9 W/g. Under the optimal conditions, the predicted values of RR and TSC were 1.90 g/g and 5.74 g/100 g, respectively, which is very close to corresponding actual values (1.83 g/g and 5.72 g/100 g). The desirability of 0.913 further validated the effectiveness of the model. The findings from this work may apply to other agricultural products.

Hot-air coupled microwave was employed to dry lotus root slices. The effects of lotus root slice thickness (5, 8, 11, 14, and 17 mm), hot-air velocity (1.5, 2.0, 2.5, 3.0, and 3.5 m/s), hot-air temperature (50, 55, 60, 65, and 70 °C), and microwave power density (2, 4, 6, 8, and 10 W/g) on drying characteristics and kinetics were studied. Results indicated that the drying process involved both the accelerating and decelerating periods but no constant rate period. The drying rate reached the maximum of 1.52 kg/kg when microwave power density was 8 W/g and reached the minimum of 0.02 kg/kg at the last stage of drying. In addition, the drying kinetics of lotus root slices were also investigated using eleven previously reported models. Among the models, the Verma et al. model was the most suitable for description of the drying behaviors of lotus root slices based on R², root-mean-square error, and chi-square. The moisture transfer from lotus root slices can be effectively described by Fick’s diffusion model. Regardless of drying conditions, the effective diffusivity coefficients ranged from 8.23 × 10^–7 to 7.08 × 10^–6 m²/s, and their variations were mostly in agreement with those of moisture ratios. The activation energy of moisture diffusion related to lotus root slices was determined to be 13.754 kJ/mol.

Приведена методика расчета скин-фактора композитного фильтра с учётом гидродинамического сопротивления потоку на кожухе, фильтровальной сетке из нержавеющей стали, в отверстиях корпуса, а также с учетом потери давления в призабойной зоне скважины, в том числе с эллиптической формой зоны проникновения, характерной для горизонтальных стволов. Приведен пример расчета скин-фактора реальной скважины. Сопоставление фактического и рассчитанного с учётом скин-фактора дебитов скважины показало хорошее совпадение, что дало возможность оценить результат оптимизации размеров и числа щелей кожуха, проницаемости сетки и размеров отверстий в корпусе композитного фильтра. Вычисления скин-факторов и дебитов скважин разных конструкций забоев показали необходимость снижения гидродинамических потерь композитного фильтра, так как они оказались наибольшими по сравнению с другими вариантами. С учётом сохранения прочности и эффективности фильтра увеличено количество щелей в поперечном сечении защитного кожуха с 15 до 20, увеличен коэффициент λ (площадь щелей к общей площади поверхности кожуха) с 0,5 до 0,55 и количество отверстий в поперечном сечении корпуса фильтра с 6 до 8. В результате скин-фактор фильтра снижен с 3,7 до 3,027. Фильтр стал сопоставим по эффективности с металлловолоконным и щелевым...

Biomass is generally regarded as a significant renewable resource, which can be used as the raw material for bioproducts. In the study, a mixture of rice straw and fermented cow manure was utilized to produce potted seedling trays, which are biodegradable and environmentally friendly. The effects of process parameters on the quality of final products were assessed by measuring damage resistance (DR) and expansion ratio (ER). Single-factor experiments and the response surface methodology (RSM) were used to optimize process parameters, including moisture content, forming pressure, mass percentage of straw (the ratio of rice straw to the mixture), and forming temperature as variables, and DR and ER of potted seedling trays as responses. The results showed that moisture content had the largest effect on DR and ER, followed by forming pressure, forming temperature, and mass percentage of straw. The optimal conditions were identified as a moisture content of 13%, forming pressure of 124 kN, mass percentage of straw equal to 8%, and forming temperature of 132 °C. There was a good agreement between the experimental data and the predicted results, indicating the reliability of the optimization process. Under the optimal conditions, the effectiveness of the regression model was further validated by the desirability of 0.97. Our findings shed new light on the perfect utilization of straws and animal manure and provided a reliable reference for the preparation of potted seedling trays from other types of biomass produced by agriculture.