林业科学Issue(4)：134-140,7.DOI:10.11707/j.1001-7488.20150417
有限差分法逆求木材导热系数
Inverse Determination of Thermal Conductivity of Wood Using Finite Difference Method
摘要
Abstract
Objective]To develop a precise,quick and economic method for determination the thermal conductivity of wood,this paper proposed a new numeral method based on the inverse finite difference method,which can overcome the drawback of traditional methods such as depending on relatively complex and expensive instrumentations. This will provide reliable data for the development of thermal conductivity’s regression equation. [Method]A one-dimensional governing equation of the heat conduction was used to describe the temperature variation inside the lumber during the heating process. The timbers obtained through tangential cut in larch ( Larix gmelinii) plantation,with dimensions of 600 mm in length,220 mm in width,and 40 mm in thickness,and moisture contents of 28. 3%,41. 2%,62. 3%,were used in the experiments. Temperature along the thickness direction was obtained via experiments. The detection of temperature was obtained using NEC Remote Scanner Jr. DC3100 with T-type in wood. With inverse finite difference method and rationalization of boundary condition,the determination of thermal conductivity in radial direction with different moisture content and temperature was achieved. Difference matrix of thermal conductivity from the discrete control equations could be solved by tridiagonal matrix algorithm (TDMA). All difference equation were programmed and run in Matlab 2010b. At the end,the variation law of thermal conductivity with the changing of moisture content and temperature was discussed and analyzed. [Result]The results showed that: 1 ) although some fluctuation along the thickness direction of thermal conductivity in larch plantation was observed,the average value (0. 106 1 W·m -1K -1,standard deviation(SD) was 0. 010 8) agreed with theoretical calculating value (0. 110 9,0. 125 2W·m -1K -1);2) MC and T had apparent effect on the thermal conductivity and the former influences slightly higher than the latter ( FMC-test is 126. 942 1,FT-test is 99. 008 3). The interaction of MC and T also had apparent effect on the thermal conductivity (FMC × T-test is 164. 297 5). The thermal conductivity increased with increasing MC and T; 3 ) Wood properties and the distribution of MC had apparent effect on the thermal conductivity. [Conclusion]Reliable temperature data in wood was obtained via experiments. The thermal conductivity in the position corresponding to temperature measuring points was obtained quickly and accurately with IFDM. Although some fluctuation of thermal conductivity was observed,the average value agreed with theoretical calculating value. It indicted that the determination of thermal conductivity with finite difference method is feasible. Compared with traditional method,the main advantage of our method is economic and unconstrained in size of specimen. The thermal conductivity of any layer of wood can be obtained. To improve precision,heat changes with moisture migration and the difference of wood properties should be considered. To expand the method, program visualization should also be researched in the future.关键词
含水率/温度/导热系数/有限差分逆求法Key words
moisture content/temperature/thermal conductivity/inverse finite different method分类
农业科技引用本文复制引用
赵景尧,付宗营,宦思琪,蔡英春..有限差分法逆求木材导热系数[J].林业科学,2015,(4):134-140,7.基金项目
国家自然科学基金项目(31270595)。 （31270595）
