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对球果─木材两用干燥室性能检测测试及其干燥质量检验结果表明,该干燥室技术性能稳定,温度均匀,干燥质量较高。 相似文献
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通过对MQ-I型木材球果两用干燥室干燥工艺的研究,确定出在MQ-I干燥中干燥球果和木材的最佳工艺路线,从而为推广使用这一新型两用干燥室提供了正确的理论依据。 相似文献
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对球果-木材两用干燥室性能检测测试及其干燥质量结果表明,该干燥室技术性能稳定,温度均匀,干燥质量较高。 相似文献
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通过计算流体力学(CFD),研究了在常规蒸汽干燥中,空气温度、相对湿度、风速及其相互作用对桦木干燥时间和能耗的影响,以期得到干燥时间短、且能耗低的桦木干燥工艺参数。应用最优拉丁超立方(Opt LHD)采样确定了设计空间中的样本点,并进行CFD数值模拟;采用三阶响应面方法构建近似代理模型,分析了干燥条件对干燥时间和能耗的影响;基于快速非支配排序遗传算法(NSGA-II)多目标优化的Pareto解集,获得最佳木材干燥条件参数。结果表明:该方法可以有效缩短干燥时间,并降低能耗,可为木材干燥工艺的优化提供参考依据。 相似文献
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给出了用于木材太阳能干燥的三种主要类型干燥室的特点、结构和技术指标,简要介绍了太阳能与除湿机联合干燥技术,分析了木材太阳能干燥技术的工艺要点,列举了该技术的优点、不足及适用范围。 相似文献
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本文介绍了常规木材干燥室的基本结构、工作原理和特点,总结目前木材干燥实际生产经验,全面地分析和论述了常规木材干燥室的合理选用方法和原则,对于生产实际具有重要的参考价值。 相似文献
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文中综述了木材热压干燥理论及试验研究,分析了热压干燥工艺对干燥时间、干燥质量和物理力学性能的影响;为了对木材热压干燥过程进行预测和工艺控制,归纳了木材热压干燥传热传质规律以及数学模型构建与求解的研究现状,也为更好地建立和完善木材热压干燥数学模型与干燥工艺奠定了基础;指出木材热压干燥及传热传质模型研究中存在的主要问题,对完善木材热压干燥机理研究与传热传质数学模型构建提出建议,并对热压干燥在人工林木材中的应用进行了展望,可为人工林木材高效高附加值利用提供参考。 相似文献
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木材干燥过程含水率和温度变化的数学模型研究 总被引:1,自引:0,他引:1
木材干燥过程存在着热质互换和能量的转移,这为从热力学的角度研究木材干燥过程提供了前提条件,因此提出利用热力学原理分析木材干燥过程含水率和温度变化规律的数学模型.首先建立描述含水率和温度变化的高阶非线性偏微分方程组,然后采用有限元分析原理将方程组离散化,再经过一系列数学运算得到方程的收敛解,具体方法为牛顿迭代法,最后通过对木材含水率和温度变化情况仿真结果的分析,验证该方法的可行性及数学模型的准确性. 相似文献
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INTRODUCTIONTheconventionaltwingmethodisgener-all3usedduringwoocldryinginChinaandothercountriesatpresent.Fluidvelocity,tem-peratUreandrelativehumidityofdryingmediaarecontrolledmainlybymoisbecontentofwood'dunngwtingprocess.Soitisveryim-portanttounderstandthephenomenonofheatandmasstransferinwoodduringdIyingproc-essformakingreasonablythewtingtechnoI-ogy-controlwtingprocess,heightenwtingquality'.decreasewtingenergyconsumptionanddiminishwtingtime.Thephenomenonofheatandmasstrans-ferinwooddurin… 相似文献
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A three-dimensional theory for the numerical simulation of deformations and stresses in wood during moisture variation is described. The constitutive model employed, assumes the total strain rate to be the sum of the elastic strain rate, the moisture-induced strain rate and the mechano-sorption strain rate. Wood is assumed to be an orthotropic material with large differences between the longitudinal, radial and tangential directions in the properties found. The influence of the growth rings, the spiral grain and the conical shape of the log on the orthotropic directions in the wood is taken account of in the model. A finite element formulation is used to describe the deformation process and the stress development during drying.The research presented in this paper is a part of the national research programme in Sweden concerning wood physics and drying. It was financially supported by the Research Foundation of Swedish Sawmills and the Swedish Council for Forestry and Agricultural Research. 相似文献
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Experimental investigation and computational analysis were performed to evaluate the influence of the ambient air parameters
during the drying process on the temperature, moisture and resulting deformations and stresses in wood samples. The numerical
procedure uses the Finite Volume Method to discretise the equations governing heat, mass and momentum balance and takes into
account the anisotropic nature of wood. The comparison of the numerical and experimental results shows very good agreements,
implying that the proposed numerical algorithm can be used as a useful tool in designing wood drying schedules.
Received 31 March 1999 相似文献
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给出木材瞬态热传导分析的基本理论,针对木材的热各向异性,利用有限元方法,对木材瞬态温度场进行有限元分析和计算,获得加热过程中木材温度场的分布与变化规律.试材选取帽儿山落叶松,仿真和试验结果表明将该方法用于细胞排列规则的针叶材是可行的,有限元计算结果与试验测量结果接近. 相似文献
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基于有限元理论木材温度场的数值仿真 总被引:2,自引:0,他引:2
对具有各向异性的木材温度场做了初步研究,给出根据木材稳态热传导分析的基本理论。针对木材的热各向异性,利用有限元的方法,对木材温度场进行了理论数值模拟计算和测量试验验证。仿真和试验结果比较可靠,误差在-3.5%~4.2%,能够满足工程计算的精度要求,证明了这种方法的有效性。 相似文献
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Some considerations in heterogeneous nonisothermal transport models for wood: a numerical study 总被引:1,自引:1,他引:0
This study compares a number of coupled heat and mass transfer models and presents numerical comparisons of phenomenological
coefficients between the four models (Stanish, Perre, Pang, and Avramidis) that are most frequently used in the literature
to describe wood-drying processes. The USDA sorption isotherm, the Hailwood-Horrobin model, was adopted to calculate the relations
between moisture content in wood and water vapor pressure at any temperature. Due to different assumptions about the driving
forces of heat and mass transfer, coefficients in each model represent different values for moisture content and temperature
and are closely related to each other. In the case of isothermal mass transfer, the moisture diffusion coefficient in the
transverse directions from the Stanish and Pang models increased with decreasing moisture content. This contradicts the Avramidis
and Perre models and numerous experimental results. Thermal diffusion effects on the drying process may not be predominant
because the nonisothermal state is relatively short. Therefore, the Perre model, which does not consider the thermal diffusion
effect, has been used successfully in the drying simulation. However, it may be erroneous in certain cases when the nonisothermal
state prevails over the system, such as building physics. The Pang model cannot explain the phenomena of thermal diffusion
and moisture thermodiffusion. It might be reasonable to modify the thermal diffusion of the Avramidis model, which is lower
than that of the Stanish model. The apparent heat diffusivity was higher than the true heat diffusivity. 相似文献