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71.
通过对奥氏体耐热钢21-4N碳化物析出行为的研究,探讨了对性能的影响,提出了改善其综合性能的措施和方法. 相似文献
72.
Mass transport in wood during drying can have different mechanisms at different periods of drying. Depending on the current moisture content (MC) and the structure of the wood, the driving forces for the mass transport are essentially different. Above the fiber saturation point (FSP), the lumens are partially saturated and the transport of liquid (free) water occurs as a consequence of capillary action. On the other hand, below the FSP, bound water within the cell walls is conveyed by diffusion, and water vapor in the lumens moves under influence of pressures gradient. Based on these considerations, a unified model is presented that takes into account the transport of the different moisture phases. Simulation of the drying of a Norway spruce sample at 50°C from about 135 to 7% MC is carried out using the finite element method (FEM). Comparison between the simulated average MC and the experimental observations obtained from X-ray computed tomography (CT) shows reasonable agreement. Possible simplifications in the model are briefly discussed as well as some aspects of the numerical implementation. Finally, the influence of absolute permeability on the average MC is studied. 相似文献
73.
《Drying Technology》2007,25(2):303-310
The aim of this work was to determine specifications for spray-drying manufacturing of sustained-release drug-loaded microparticles with potential application in dentistry. Chitosan was used as the microencapsulation polymer and ketoprofen as the model drug. A 1:1 chitosan/ketoprofen suspension was spray-dried under different operating conditions. The size distribution, morphology, total drug load, and release profile of the powders were characterized. In vitro release studies were performed with the powder samples entrapped in cellulose dialysis tubes. The microparticles produced had a narrow size distribution (mean diameter ranging from 2.11 to 3.27 µm), good sphericity, and a smooth surface. In vitro release studies showed a linear drug dissolution behavior. 相似文献
74.
《Drying Technology》2007,25(10):1621-1632
A study was performed to determine the drying characteristics and quality of barley grain dried in a laboratory scale spouted-bed dryer at 30, 35, 40, and 45°C and an inlet air velocity of 23 m/s-1, and in an IR-convection dryer under an infrared radiation intensity of 0.048, 0.061, 0.073, and 0.107 W cm-2 at an air velocity of 0.5 m/s-1. The results show that the first, relatively short, phase of a sharp decrease in the drying rate was followed by the phase of a slow decrease. The time of barley drying depended on temperature of inlet air in a spouted-bed dryer and on radiation intensities in an IR-convection dryer. Barley drying at 45°C in a spouted-bed dryer was accompanied by the lowest total energy consumption. The average specific energy consumption was lower and the average efficiency of drying was higher for drying in a spouted-bed dryer. The effective diffusivities were in the range 2.20-4.52 × 10-11 m2 s-1 and 3.04-4.79 × 10-11 m2/s-1 for barley dried in a spouted-bed and in an IR-convection dryer, respectively. There were no significant differences in kernel germination energy and capacity between the two drying methods tested. 相似文献
75.
76.
石英砂脱水性能的研究 总被引:1,自引:0,他引:1
通过大量试验结果 ,研究了各种粒度范围的石英砂的脱水性能 ,包括沉降特性、过滤性能、极限压缩浓度等 ,为进行此类产品的固液分离提供了重要的参考数据 相似文献
77.
PP-g-MAH对PA6/PP/TLCP三元共混物的增容改性作用 总被引:2,自引:0,他引:2
研究了PP-g-MAH对PA6/PP/TLCP三元共混体系的增容作用以及对共混物流变性能和力学性能的影响。通过共混物的DSC、SEM、POM、流变性能和力学性能测试,结果表明,PP-g-MAH对共混体系有明显的增容作用,共混物的力学性能(拉伸强度和冲击强度)得到提高;由于TLCP的加入,共混物的熔体粘度大大低于PA6的熔体粘度。 相似文献
78.
A mathematical model for the drying rate of granular particles in a multistage inclined fluidized bed(IFB) is presented from the standpoint of simultaneous heat and mass transfer, with taking the effect of mechanical vibration added vertically into consideration.
Steady-state distributions for the temperatures and concentrations of the particles and the heating gas, and for the moisture content of the particles are numerically calculated based on the present model. The calculated results show fairly good agreement with the experimental data, which were obtained from the drying experiments of brick particles in a three-stage IFB using comparatively low temperature air(40-60°C) as the heating gas.
It has been found within the range of the experimental conditions employed that, the mechanical vibration added vertically enhances the over-all drying rate of the particles and its effect can be considered equivalent to an increase in the air velocity. 相似文献
Steady-state distributions for the temperatures and concentrations of the particles and the heating gas, and for the moisture content of the particles are numerically calculated based on the present model. The calculated results show fairly good agreement with the experimental data, which were obtained from the drying experiments of brick particles in a three-stage IFB using comparatively low temperature air(40-60°C) as the heating gas.
It has been found within the range of the experimental conditions employed that, the mechanical vibration added vertically enhances the over-all drying rate of the particles and its effect can be considered equivalent to an increase in the air velocity. 相似文献
79.
80.
《Drying Technology》2007,25(1):75-84
This article proposes a multiscale computational model able to calculate energy consumption in a batch lumber kiln. A dual-scale computational model of wood drying deals with the boards/stack interaction and serves as a basis for the present work. A new module was added here that calculates heat losses through kiln walls (convection, condensation) and the energy used by each kiln component (fans, heating elements, humidifier, vacuum pump, etc.). The corresponding mathematical formulation is presented and then theoretical results are compared to those collected in an industrial vacuum kiln. As application example, the effect of air reversal, air velocity, and kiln insulation are exhibited, which depicts the great potential and prospects of this new tool for energy savings in relation to the product quality. 相似文献