Simultaneous Estimation of the Thermophysical Properties of Selected Liquid Dairy Products by a Transient Heat Flow Probe Method

The thermophysical properties of reconstituted whole milk, skim milk, and whey were measured at various temperatures and concentrations. A new method for the simultaneous determination of thermophysical properties using a modified version of current probe theory method was proposed. Two new correction coefficients were introduced, and using the values of these coefficients and an approximate solution of the heat conduction equation, the thermal conductivity and thermal diffusivity of each sample were determined. The specific heat of each sample was estimated from the definition of thermal diffusivity. These properties were expressed as a function of concentration and temperature.     

Simultaneous Estimation and Modeling of Thermophysical Properties of Big-Eyed Tuna and Pacific Cod

The thermophysical properties (thermal conductivity, thermal diffusivity, and specific heat) of big-eyed tuna and pacific cod were measured at various temperatures (5–50°C) by the modified version of current probe method. The optimal prediction models for these thermophysical properties were determined. The random model was applied to predict the thermal conductivity of seafood in a wide range of temperature and it provided the accurate predictions for the samples. The thermal diffusivities of the samples could be predicted by Martens’s equation. An additive relationship exists between the specific heat of the sample, the composition, and the specific heat of each component.     

基于瞬变平面热源法的纤维热导率测试

为解决单纤维热导率不易直接测试的难题,基于两相复合介质串并联等效热导率物理模型,采用瞬变平面热源法对环氧树脂-纤维复合体系进行测试,并计算出单纤维轴向和径向的热导率。结果表明,采用该方法可获得纤维热导率,且纤维轴向的热导率要明显大于纤维径向的热导率,验证了纤维热学性能的各向异性。复合体系中两相材料的热导率差异、纤维所占体积比及物理模型、仪器的加热功率、测试时间的设定等对纤维热导率结果影响显著。当纤维和树脂的热导率差异较大时,采用并联模型计算较为准确,且随着体积含量的增加,纤维热导率增加,直到平衡。随加热功率和测试时间的增大,复合体系的热导率增大。     

基于结构特征的织物热传递性能预测研究进展

为了预测织物热传递性能,更好地进行织物设计,从而提高织物的热舒适性能,从不同建模方法的角度介绍了与织物结构参数及内部特征相关的织物热传递性能预测模型,包括统计模型、人工神经网络模型、数学理论模型和有限元模型,并分析了各类预测模型的特点和适用范围。回顾并总结了近年来国内外织物传热模拟的研究现状。此外,总结了含水分织物以及含相变材料织物的热传递模型及研究进展。综合以上文献分析,指出可通过优化织物结构特征提升织物热传递性能,并提出织物传热性能预测研究的发展趋势,为服装热舒适性研究提供新的思路。