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HEAT AND MASS TRANSFER PHENOMENA IN A CAPILLARY-POROUS BODY WITH PARTICULAR REFERENCE TO LUMBER.

机译:毛细管多孔体内的传热和传质现象,特别是对木材的引用。

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The most common method of drying wood for the furniture industry is in kilns at temperatures below 180(DEGREES)F. The procedures currently in use involve more or less empirically determined drying schedules which require a week or more residence time in the kiln.; With rapidly increasing energy costs and the demand for shorter processing times for green wood, interest has developed in perfecting faster and more efficient ways of drying lumber. High temperature drying is being considered as an alternative; however, if care is not taken, the severe conditions required by high temperature drying may lead to degradation of the wood. Successful high speed drying will require a more thorough understanding of the drying process and the measurement of variables such as surface temperature, interior temperatures, and heat transfer coefficients.; In this work, techniques were developed for accurately measuring the surface and interior temperatures of the drying wood. Yellow poplar lumber was dried at dryer temperatures from 215(DEGREES)F to 300(DEGREES)F with wet bulb temperatures ranging from 130(DEGREES)F to 180(DEGREES)F in order to generate surface and interior temperature profiles and wood moisture content profiles. Detailed temperature and moisture profiles for these runs are presented.; A mathematical model, based on Luikov's equations, was developed for use in predicting surface and interior temperature profiles and moisture profiles during the drying of lumber. A fixed network procedure developed by Crank was used to solve the model equations.; Using the model and the experimental data for yellow poplar, empirical correlations were developed for predicting the evaporation rate at the surface of the wood during the constant rate period and the overall diffusion coefficient.; The results from the model were compared with the experimental data obtained during this study, with the results of a model described in the literature, and with experimental data from the literature. The model developed in this work was found to predict drying curves from the literature better than the model described in the literature.
机译:家具工业中最干燥的木材干燥方法是在温度低于180°F的窑中干燥。当前正在使用的程序或多或少地根据经验确定了干燥计划,这需要在窑中停留一周或更长时间。随着能源成本的快速增长和对生材木材更短加工时间的需求,人们对完善更快,更高效的木材干燥方法产生了兴趣。高温干燥被认为是替代方法。但是,如果不注意,高温干燥所需的严酷条件可能导致木材降解。成功的高速干燥将需要对干燥过程和变量的测量有更透彻的了解,例如表面温度,内部温度和传热系数。在这项工作中,开发了用于精确测量干燥木材的表面和内部温度的技术。将黄杨木材在烘干机温度从215°F至300°F的干燥温度下干燥,湿球温度从130°F至180°F的温度范围进行干燥,以产生表面和内部温度曲线以及木材含水量个人资料。给出了这些运行的详细温度和湿度曲线。建立了基于Luikov方程的数学模型,用于预测木材干燥过程中的表面和内部温度曲线以及湿度曲线。用Crank开发的固定网络程序求解模型方程。利用该模型和黄杨的实验数据,建立了经验相关性,以预测恒定速率期间木材表面的蒸发速率和总扩散系数。将模型的结果与本研究中获得的实验数据,文献中描述的模型结果以及文献中的实验数据进行比较。发现在这项工作中开发的模型比文献中描述的模型更好地预测了文献中的干燥曲线。

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