A numerical simulation for a model of wood drying process is considered. The model is given by a couple of nonlinear differential equations. One is a nonlinear parabolic equation and the other one is a nonlinear ordin...A numerical simulation for a model of wood drying process is considered. The model is given by a couple of nonlinear differential equations. One is a nonlinear parabolic equation and the other one is a nonlinear ordinary equation. A difference scheme is derived by the method of reduction of order. First, a new variable is introduced and the original problem is rewritten into a system of the first-order differential equations. Secondly, a difference scheme is constructed for the later problem. The solvability, stability and convergence of the difference scheme are proved by the energy method. The convergence order of the difference scheme is secondorder both in time and in space. A prior error estimate is put forward. The new variable is put aside to reduce the computational cost. A numerical example testifies the theoretical result.展开更多
Intermittent heating for drying of small diameter Larch lumbers is investigated experimentally. The lumbers were dried using an experimental drying schedule. Moisture content (MC) of the lumber was continuously record...Intermittent heating for drying of small diameter Larch lumbers is investigated experimentally. The lumbers were dried using an experimental drying schedule. Moisture content (MC) of the lumber was continuously recorded and final drying defects were examined. The drying curves showed that the drying rate was a constant in the early stage of intermittent heating drying and decreased evidently when the MC was about 18% (intermittent 2h) and 20% (intermittent 6h). The drying quality reached the second (intermittent 2h) and first grade (intermittent 6h) of the Chinese National Standard. The visual drying defects, especially the check extent along grains were reduced with intermittent heating. When the intermittent time increased, the effect was more obvious.展开更多
Drought research requires data on precipitation and actual soil moisture of fields because precipitation is variable among years and the soil textures differ with crop fields. Measurement of soil water content in the ...Drought research requires data on precipitation and actual soil moisture of fields because precipitation is variable among years and the soil textures differ with crop fields. Measurement of soil water content in the field is simple but labor-intensive. A prototype of an automatic field data monitoring system has been recently developed to collect data more efficiently. Using this system, data of soil water contents was successfully transmitted onto the personal computer approximately 700 m away from wheat field plots, for the period from March to May which was critical for soil drying and wheat growth. In addition, sample data of soil water content and grain yield was obtained from field plots of three bread wheat genotypes.展开更多
The emission and contact drying kinetics of the paper mill sludge (PMS) were studied through experiments carried out in a paddle dryer. To get a better understanding of its drying mechanism, a penetration model develo...The emission and contact drying kinetics of the paper mill sludge (PMS) were studied through experiments carried out in a paddle dryer. To get a better understanding of its drying mechanism, a penetration model developed by Tsotsas and Schlünder (1986) was used to simulate the drying kinetics of the PMS. The result indicated that this kinetics could be divided into three phases: pasty, lumpy and granular phases, and could be successfully simulated by the penetration model as the related sludge parameters were integrated into the model. The emission rate curves of the volatile compounds (VCs) were interrelated to the drying rate curve of the PMS, especially for volatile fatty acids (VFAs) and ammonia in this study.展开更多
基金The National Natural Science Foundation of China (No10471023)
文摘A numerical simulation for a model of wood drying process is considered. The model is given by a couple of nonlinear differential equations. One is a nonlinear parabolic equation and the other one is a nonlinear ordinary equation. A difference scheme is derived by the method of reduction of order. First, a new variable is introduced and the original problem is rewritten into a system of the first-order differential equations. Secondly, a difference scheme is constructed for the later problem. The solvability, stability and convergence of the difference scheme are proved by the energy method. The convergence order of the difference scheme is secondorder both in time and in space. A prior error estimate is put forward. The new variable is put aside to reduce the computational cost. A numerical example testifies the theoretical result.
基金Sponsored by Huo Yingdong Fund(Grant No.81022) Sponsored by the Science and Technology Project Foundation of Harbin City( Grant No.2004AFX XJ021).
文摘Intermittent heating for drying of small diameter Larch lumbers is investigated experimentally. The lumbers were dried using an experimental drying schedule. Moisture content (MC) of the lumber was continuously recorded and final drying defects were examined. The drying curves showed that the drying rate was a constant in the early stage of intermittent heating drying and decreased evidently when the MC was about 18% (intermittent 2h) and 20% (intermittent 6h). The drying quality reached the second (intermittent 2h) and first grade (intermittent 6h) of the Chinese National Standard. The visual drying defects, especially the check extent along grains were reduced with intermittent heating. When the intermittent time increased, the effect was more obvious.
文摘Drought research requires data on precipitation and actual soil moisture of fields because precipitation is variable among years and the soil textures differ with crop fields. Measurement of soil water content in the field is simple but labor-intensive. A prototype of an automatic field data monitoring system has been recently developed to collect data more efficiently. Using this system, data of soil water contents was successfully transmitted onto the personal computer approximately 700 m away from wheat field plots, for the period from March to May which was critical for soil drying and wheat growth. In addition, sample data of soil water content and grain yield was obtained from field plots of three bread wheat genotypes.
基金Project (No. 2007C03003) supported by the Key Project of Science and Technology of Zhejiang Province, China
文摘The emission and contact drying kinetics of the paper mill sludge (PMS) were studied through experiments carried out in a paddle dryer. To get a better understanding of its drying mechanism, a penetration model developed by Tsotsas and Schlünder (1986) was used to simulate the drying kinetics of the PMS. The result indicated that this kinetics could be divided into three phases: pasty, lumpy and granular phases, and could be successfully simulated by the penetration model as the related sludge parameters were integrated into the model. The emission rate curves of the volatile compounds (VCs) were interrelated to the drying rate curve of the PMS, especially for volatile fatty acids (VFAs) and ammonia in this study.
