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This study designed a corn kernel drying device and optimized the structure of key components. FLUENT software was used for numerical simulation of wet heat coupling. The differences in physical fields were compared within the drying section before and after optimization. The optimized drying section exhibited improved drying uniformity, drying efficiency, and drying quality. The optimized drying section took 180 seconds for the temperature at the center point to reach the expected value, while the mixed flow drying section took 240 seconds. The moisture content of the optimized drying section decreased to 3.79% at this point, while that of the mixed flow drying section was 2.89%. The results indicated that the drying uniformity and efficiency of the optimized drying structure were higher than those of the mixed flow drying structure. This research provides important data for the design of corn drying equipment.

Nondairy fermented probiotic powder was developed based on stabilized wheat germ through mixed fermentation (Lactobacillus acidophilus and Lactobacillus plantarum) and electrospraying process. In the first step, the effect of mixed fermentation on lipase and lipoxygenase activity of wheat germ was investigated. The results showed a significant reduction in the activity of both enzymes (82.72% for lipase and 72% for lipoxygenase), therefore, mixed fermentation effectively stabilizes the wheat germ. In the next step, after the preparation of the solutions for drying process and investigating the physical properties (surface tension, electrical conductivity, and viscosity) of the solutions, the electrosprayability of the samples was evaluated at different conditions and revealed that 18 kV applying voltage, 0.3 flow rate, and 12 cm distance between tip to collector was the best for electrospraying the 20% solution of fermented wheat germ with morphologically most semi‐uniform particles. Finally, the viability of the probiotics after drying process and during the storage at 25°C was examined. The number of initial cells counted as 14.48 ± 0.2 log cfu/g and the viability studies showed 0.55 log cfu/g decrease in the number of viable bacteria from initial count as a result of the electrospraying process. Furthermore, 7.86 ± 0.03 log cfu/g in freeze‐dried and 9.05 ± 0.45 log cfu/g in electrosprayed samples survived after 70 days of storage. Wheat germ is a potential source of prebiotics though exhibiting an unstable nature; Mixed fermentation reduces the lipase and lipoxygenase activity of wheat germ; Fermented wheat germ solution has good electrosprayability; More than 96% of probiotics maintained their viability in electrospraying process; Electrospraying does less harm to the bacteria in comparison with freeze‐drying;

Research Highlights: Investigations of evapotranspiration in a mature mixed beech-fir forest stand do not indicate higher resilience towards intensified drying-wetting cycles as compared with pure beech stands. Background and Objectives: Forest management seeks to implement adaptive measures, for example, the introduction of more drought resistant species into prevailing monospecific stands to minimize forest mortality and monetary losses. In Central Europe this includes the introduction of native silver fir (Abies alba) into monospecific beech (Fagus sylvatica) stands. In order to determine, if the introduction of fir would improve the resilience against drier conditions, this study investigates water relations of a mature pure beech and a mature mixed beech-fir stand under natural as well as reduced water availability. Materials and Methods: Sap flow rates and densities were measured in two consecutive years using the heat ratio method and scaled using stand inventory data and modeling. Results: Transpiration rates estimated from sap flow were significantly higher for beech trees as compared with silver fir which was attributed to the more anisohydric water-use strategy of the beech trees. We estimate that stand evapotranspiration was slightly higher for mixed stands due to higher interception losses from the mixed stand during times of above average water supply. When precipitation was restricted, beech was not able to support its transpiration demands, and therefore there was reduced sap flow rates in the mixed, as well as in the pure stand, whereas transpiration of fir was largely unaffected, likely due to its more isohydric behavior toward water use and access to moister soil layers. Thus, we found the rates of evapotranspiration in the mixed beech-fir stand to be smaller during times with no precipitation as compared with the pure beech stand, which was accountable to the severely reduced transpiration of beech in the mixed stand. Conclusions: We conclude that smaller evapotranspiration rates in the mixed beech-fir stand might not be the result of increased water use efficiency but rather caused by restricted hydraulic conductivity of the root system of beech, making mixed beech-fir stands at this site less resilient towards drought.

Satsuma mandarins are good sources of vitamin C and can be used as raw materials to produce novel plant-based food ingredients including satsuma mandarin juice powders (SJP). Food powders produced via spray drying often show thermal degradation due to the drying conditions and high drying air temperatures. The aim of this study was to evaluate the effect of using different spray drying configurations, including concurrent (CC), mixed flow (MX), and combined (CC + MX), at two inlet air temperatures (160 and 180 °C) on the physicochemical properties of SJP. Remarkably, SJP produced using the CC spray drying configuration exhibited a higher vitamin C content (3.56–4.01 mg/g) and lower moisture levels (15.18–16.35 g/100 g) than powders produced via MX or CC + MX. The vitamin C content of MX and CC + MX powders ranged from 2.88 to 3.33 mg/g. Meanwhile, all SJP had water activity values below 0.19. Furthermore, MX powders displayed the largest mean particle sizes (D50) (8.69–8.83 µm), higher agglomeration, and a rapid dissolution. Despite these differences, all SJP variants exhibited consistent color, surface area, and pore volumes. Notably, powders dried at higher inlet air temperatures (180 °C) showed less vitamin C content and increased thermal damage when compared with powders dried at 160 °C inlet air temperature. This study demonstrated the feasibility of producing high-quality SJP with an extended shelf life. SJP can be used as a novel plant-based ingredient in different food applications.

In order to solve the problem of inconsistent moisture content in particles during the drying process of tiger nuts (Cyperus esculentus) due to uneven air flow and temperature distribution in the drying chamber, an open-hole corner box was designed based on the principle of negative pressure micro-perforated air supply. Using computational fluid dynamics (CFD) and discrete element method (DEM) simulation, coupled with the basic theory of interphase heat and mass transfer, a mathematical model for interphase heat and moisture coupling transfer was established. The effects of different aperture rates of corner boxes in the drying chamber, spatial location arrangement, and other related variables on the airfield distribution, temperature field distribution, tiger nut temperature, and moisture content changes were investigated. The results show that the average air velocity below the air inlet gradually increases as the opening ratio increases. When the opening rate is 0.33%, the wind field uniformity is better, and the inhomogeneity of the drying chamber wind field is improved. As the lateral distance increases, the consistency of the moisture content distribution increases and then decreases, and the flow rate of the tiger nuts gradually increases when the grain is discharged. The rate of decrease in water content decreases gradually with the increase in longitudinal distance. When the wind speed reaches 4 m/s, the drying chamber wind field is more uniform, and the water vapor diffusion efficiency at the outlet is basically the same. Therefore, the appropriate corner box has a horizontal distance of 320 mm and a longitudinal distance of 420 mm, providing a basis for the design of tiger nut drying equipment.

Co-occurring species may adopt different water-use strategies to adapt to limited soil water. In Jiuzhaigou Valley, a continuous decline in soil water after an initial recharge from the thawing of snow and frozen soil in early spring was observed, but its effects on the sap flow dynamics of co-occurring species are not well understood. To clarify the species-specific water-use strategy, variations in sap flow and environmental conditions were investigated for two co-occurring species (Betula albosinensis Burk. and Pinus tabuliaeformis Carr.) in a mixed forest during a transition from the wet to dry period in 2014. Sap flow was measured using Granier-type thermal dissipation probes, and the soil-water content was measured using time-domain reflectometry probes for a successive period. Our study showed that B. albosinensis maintained relatively high transpiration until late into the season regardless of soil moisture, while the transpiration of P. tabuliformis showed a continuous decrease in response to seasonal soil drying. Sap flow for both species exhibited a marked hysteresis in response to meteorological factors and it was conditioned by the soil-water status, especially in the afternoon. We found that P. tabuliformis was sensitive to soil-water conditions, while for B. albosinensis, the sap flow was not very sensitive to changes in soil-water conditions. These results indicate that B. albosinensis could manage the water consumption conservatively under both dry and wet conditions. These results may have implications for evaluating the species-specific water-use strategy and carrying out proper reforestation practices.

Purpose The purpose of this paper is to analyze the thermal and fluid dynamic behaviors of mixed convection in air because of the interaction between a buoyancy flow and a moving plate induced flow in a horizontal no parallel-plates channel to investigate the effects of the minimum channel spacing, wall heat flux, moving plate velocity and converging angle. Design/methodology/approach The horizontal channel is made up of an upper inclined plate heated at uniform wall heat flux and a lower adiabatic moving surface (belt). The belt moves from the minimum channel spacing section to the maximum channel spacing section at a constant velocity so that its effect interferes with the buoyancy effect. The numerical analysis is accomplished by means of the finite volume method, using the commercial code Fluent. Findings Results in terms of heated upper plate and moving lower plate temperatures and stream function fields are presented. The paper underlines the thermal and fluid dynamic differences when natural convection or mixed convection takes place, varying minimum channel spacing, wall heat flux, moving plate velocity and converging angle. Research limitations/implications The hypotheses on which the present analysis is based are two-dimensional, laminar and steady state flow and constant thermo physical properties with the Boussinesq approximation. The minimum distance between the upper heated plate of the channel and its lower adiabatic moving plate is 10 and 20 mm. The moving plate velocity varies in the range 0-1 m/s; the belt moves from the right reservoir to the left one. Three values of the uniform wall heat flux are considered, 30, 60 and 120 W/m2, whereas the inclination angle of the upper plate θ is 2° and 10°. Practical implications Mixed convection because of moving surfaces in channels is present in many industrial applications; examples of processes include continuous casting, extrusion of plastics and other polymeric materials, bonding, annealing and tempering, cooling and/or drying of paper and textiles, chemical catalytic reactors, nuclear waste repositories, petroleum reservoirs, composite materials manufacturing and many others. The investigated configuration is used in applications such as re-heating of billets in furnaces for hot rolling process, continuous extrusion of materials and chemical vapor deposition, and it could also be used in thermal control of electronic systems. Originality/value This paper evaluates the thermal and velocity fields to detect the maximum temperature location and the presence of fluid recirculation. The paper is useful to thermal designers.

Abstract The Reynolds equation has been widely applied in lubrication analyses, but the extent and limit of its application have not been fully explored. Great efforts have been made so that the solution convergence speed and accuracy are significantly improved. However, while the working conditions are severe, such as extremely heavy load, low speed, and low viscosity due to temperature increase, the lubricant film thickness becomes very thin and surface contact may occur. As a consequence, the lubrication solution becomes difficult. Contact and thin-film or mixed lubrication under severe conditions are of great importance, as many components operate in such regimes. This article investigates the solution evolution of the Reynolds equation as the entraining velocity decreases, using the unified mixed elastohydrodynamic lubrication (EHL) model presented by Hu and Zhu. By comparing the ultra-low speed solution of the Reynolds equation with that of dry contact analysis, it is found that the solution of the Reynolds equation finally converges to those of the corresponding dry contact under otherwise the same operating conditions. The results manifest that with the unified solution approach the Reynolds equation system can be used to handle the situation of dry contact and mixed lubrication, in which both hydrodynamic lubrication and surface contact coexist.

Non-uniform moisture content distribution of grains at the discharge of Mixed-Flow Grain Dryers is one of the sources of product quality loss during subsequent storage. Unfavorable design of this kind of dryers may cause uneven residence times of single grain portions resulting in non-uniform drying. It is then of paramount importance to understand the physical phenomena that control the flow of grains in a mixed-flow dryer to guarantee their quality and minimize the risk of quality loss and waste of energy, thereby optimizing the process drying condition. With this objective, a two dimensional simulation model for the grain mass flow in a mixed-flow dryer based on Discrete Element Method (DEM) has been developed. The influences of the side walls and air ducts on solids mass flow were studied by evaluating the residence time distribution (RTD), particle velocity profiles and particle trajectories. The simulation results were validated with experiments using a semi-technical dryer test station with transparent Plexiglas front wall. The obtained results revealed the complexity of the drying process, the influences of the wall friction and half air ducts positioned directly on the wall on the bulk particle movement. Grains in mixed-flow dryers have different vertical velocities resulting in different residence times of every single portion of grains. The experimental validation confirms and verifies the DEM calculation ability for predicting particle flow.

The numerous cases of the upper headwaters drying are observed in the plains of the Middle Volga region. The reasons of the streamflow change pertain to the reduction of forest vegetation and the change of its species composition. More than 1000 cartographic materials for more than 200 years, as well as aerial and satellite imagery were used during the research of forest vegetation breadth. Currently, the forest and the forest-field landscapes prevail in the north of Tatarstan, where coniferous-deciduous forests are widespread. The forest-fields, as well as the field landscapes are common in the west and south of Tatarstan, where deciduous forests and forest-steppe are prevalent. In the field landscapes the water runoff in the flood time increases to 65% of the total annual runoff, while the monthly summer runoff of low water reduces by 2.5 times compared to forest landscapes. The studies have shown that over the past about140 years the quantity of the first-order watercourses has reduced by 1.5 times in the area of mixed forests, whilst in the forest-steppe zone the quantity of the first-order watercourses has decreased by nearly 2.7 times. At the same time woodland in different regions of Tatarstan has decreased by 1.6-2.8 times for the same period of time. Low of the forest cover (17.9%), as well as the species composition of forests, in which the coniferous species as the most valuable for the infiltration does not exceed 24% from the forest area, are characterized for of Tatarstan territory. Coniferous plantations by more than half are presented the unstable monocultures of pine.