基于辐射衰减特征的隔热防护织物有效导热系数简化模型

高温下辐射传热对织物热传递过程贡献显著,为此,介绍火灾高温环境下的耐高温防护织物的内部传热特点,进而提出高温下织物有效导热系数数值传热模型.针对火灾等高温环境下耐高温防护织物内部热辐射渗透衰减问题进行分析,应用有限差分法对隔热防护织物的有效导热系数模型进行数值分析.通过数值求解传热方程,计算出织物的稳态有效导热系数,且...     

消防服外层织物参数对组合面料热防护性能的影响

选择不同消防灭火服外层织物,将其与防水透气隔热层、舒适层组成的组合面料进行热防护值测试,分析消防灭火服外层织物基本参数与热防护性能之间的关系,研究消防灭火服外层织物结构、材料导热系数、热收缩率对其热防护性能的影响。结果表明：消防灭火服外层织物热防护性能与材料导热系数、遇热产生的气腔高度、表/里层经纬密度配置显著相关。在相同重量下,对热防护值要求较高的消防灭火服进行外层面料设计时,外层织物在组织结构上应采用双层结构,其表/里层经纬密度配比接近1.5∶1;在材料选用上,表层材料热收缩率应相对较大,里层材料热收缩率应较小且导热系数低。     

织物热传导机理的分析和探讨

分析了纺织品传热机理。从宏观角度看，纺织品作为纺织纤维和空气的集合体，其传热途径包括传导、对流、辐射和伴随着水汽传输而发生的潜热传递；从微观角度看，纺织品是声子作为载体实现热传导的。最后还介绍了影响织物导热系数的各个因素。     

织物热传导机理的分析和探讨

分析了纺织品传热机理。从宏观角度看,纺织品作为纺织纤维和空气的集合体,其传热途径包括传导、对流、辐射和伴随着水汽传输而发生的潜热传递;从微观角度看,纺织品是声子作为载体实现热传导的。最后还介绍了影响织物导热系数的各个因素。     

织物结构密度对织物导热性能影响的研究

通过研究同种涤纶纱线不同经密和纬密系列织物导热性能的差异,探讨了织物结构密度对织物导热系数的影响,从而得出织物结构密度的变化导致织物表观密度、织物含气性变化,它们是影响织物导热系数的直接因素,并且都是线性关系的结论.     

织物导热系数的试验研究

本文简述试验装置、方法及其可靠性,根据试样的特点选定了导热系数计算式。在调节试样温度及回潮率的同时,进行了一系列的试验,取得了有关数据,获得了不同条件下的导热系数值。文中针对织物的温度及含水对导热系数的影响进行了分析,并对试样的合理厚度进行了探讨。     

开放/封闭空气层对阻燃织物热防护性能的影响

为探究衣下空气层间的传热方式对阻燃织物外观性能和阻燃织物系统传热机制的影响,基于热防护性能(TPP) 实验装置,构建开放式和封闭式空气层以模拟实际着装时“服装-人体皮肤”的空间关系。利用彩色图像处理方法对比热暴露前后的织物外观和热收缩情况,从能量传递、TPP值和二级烧伤时间角度评估“织物-空气层”系统的传热特性和热防护性能。结果表明:空气层的介入会降低热传递效率,进而提升阻燃织物的热防护性能,但会加速织物老化,加剧织物热收缩;当打开空气层与周围环境热量交换的通路时,空气层间热量的流动路径变复杂,且织物的热防护性能进一步提升。     

新型防护织物热辐射系数测试仪

描述了一种能够测量高温对流辐射环境下防护织物辐射系数的测试仪,综合考虑了对流、辐射换热的耦合影响,采用数值分析方法计算对流换热量,建立了基于虚拟仪器技术的系统测控平台,着重解决了封闭空间内辐射对流联合传热下的对流传热系数不确定性问题。实验结果表明,该装置测试值符合实际要求,优于其它测试方法,特别适合于测量对流辐射热源共同作用下的织物热辐射系数。     

玻璃纤维保温纸导热系数的理论计算与实验研究

建立玻璃纤维均匀排列的导热模型对玻璃纤维保温纸的等效导热系数进行预测.根据分形维数代表保温材料内部纤维排列的杂乱程度,通过实际材料与理论模型分形维数的比值来对保温材料进行纤维排列不均匀度的修正.依据等效热阻法,确立基于修正系数基础上的导热系数计算通用公式.通过对在不同玻璃纤维直径和不同孔隙率条件下计算结果的分析,讨论玻璃纤维直径和材料孔隙率对保温纸导热系数的影响,在此基础上确立基于材料孔隙率的导热系数近似简易预测公式.文中导热模型推导出的通用公式与预测公式的计算结果与实验结果吻合较好,所以可以用该计算模型来预测材料的导热系数.     

织物热传递性能的影响因素

在分析织物热传递机理的基础上,详细阐述了影响织物热传递性能的主要因素。织物的热传递机理,以纺织品为研究对象,其传热方式包括传导、对流、辐射和伴随着水汽传输而发生的潜热传递;影响织物热传递性能的因素主要有：纤维导热系数、织物结构、织物结构参数和环境温度,现从这四个方面研究了其对织物热传递性能的影响。     

纬编针织物导热性能的有限元仿真

为了提出一种用于优化、评估、预测针织物导热性能的方法,文章探索了纬编针织物热量传递的有限元仿真模拟,尤其是夏季汗衫面料,因为其导热性能与人体舒适性密切相关。首先使用织物厚度仪和超景深显微镜获取织物结构参数,通过插入三次B样条曲线建立纬平针织物的三维几何模型。然后将单元线圈模型导入有限元分析软件STAR-CCM+中,通过网格划分、边界设置、迭代计算步骤进行数值计算,并和实验值进行了比较分析,误差在4%以内。表明此方法具有一定的实用性,可用于预测纬编针织物的导热性能。     

A study of the thermal protective performance of the outer fabric material for fire proximity suits

The thermal performances such as thermal conductivity, radiant heat reflection, X-ray diffraction spectra, thermogravimetric data, and thermal protection performance (TPP) of three types of outer fabric materials for fire protection suits were compared. Three types of fire proximity suits’ outermost fabrics are high silica glass fiber fabrics (A1), high silica glass fiber fabrics (B1), and continuous basalt fiber fabrics (XW). The explanation and analysis of the reasons for the difference in thermal protective performance among the three types of materials were carried out, one by one, from the perspective of the microscopic molecular architecture of the yarn and macroscopic fabric structure. The sizes of the influence for related indicators of all types of thermal performances on the TPP value of the fabric were calculated. According to the analysis and calculation results, it can be concluded that the thermal conductivity of the fabric is the decisive factor influencing the size of the TPP value for the fabric. Therefore, reducing the thermal conductivity of the fabrics and improving the thermal insulation efficiency of the fabric is the best way to improve their thermal protective performance.     

结构参数对超高分子量聚乙烯织物导热性的影响

为了提高服装热量的传导,采用导热率较高的超高分子量聚乙烯(UHMWPE)纱线作为纬纱与涤纶进行交织制成织物,并以电热片作为热源,通过铂电阻测温仪测量距离热源边界0、2、4 cm处织物表面温度随时间的变化。采用变量分离法测试纤维种类、纱线线密度、织物密度以及织物组织结构等因素对超高分子量聚乙烯织物导热性的影响。结果表明:含UHMWPE纱线交织物的导热性明显好于涤纶/涤纶和涤纶/锦纶交织物,且纱线越粗、织物密度越大、组织单元内纱线交织次数越少,织物导热性越好。     

形变状态下热防护织物的蓄放热双重特性

为了探究形变状态下热防护织物的防护机制,研发了形变状态下织物蓄放热特性测试仪,在此基础上对拉伸形变状态下6种热防护织物的蓄热防护性能和放热危害性能进行量化研究。结果表明:随着织物拉伸率的增加,织物在热暴露阶段的累计蓄热量降低,而皮肤得热显著提升,织物的热防护性能下降;当双层织物系统发生拉伸形变时,外层织物较其隔热层通常蓄积更多的热量,织物系统累计蓄热量的降低主要源于隔热层蓄热量下降;在冷却阶段,织物释放至皮肤的累计蓄热回放量随着其拉伸率的增加而逐渐降低,织物的蓄热回放效率逐渐增大。织物发生拉伸形变时,其累计蓄热回放量与累计蓄热量呈正比。     

蒸汽暴露条件对织物热防护性能的影响

为评价蒸汽压力、蒸汽与人体相对距离等条件对织物中热湿传递的作用规律,在蒸汽暴露条件下,测量不同蒸汽压力与喷射距离时织物的热防护性能,分析织物内储水量、蒸汽渗透量与热防护性能之间的关系,并探究蒸汽压力对储水量、渗透量的影响规律。结果表明:蒸汽暴露条件下,增大蒸汽压力与减少喷射距离能够降低织物的隔热性能,明显影响织物蒸汽热防护性能;织物透气性与皮肤二级烧伤时间呈显著负相关关系;另外,储水量、渗透量与蒸汽压力呈现正相关,且分别与织物的回潮率和透气性呈现正相关;降低水分吸收和减少蒸汽渗透是提高织物热防护性能的重要因素。     

Effect of structural parameters on thermal protective performance and comfort characteristic of fabrics

In an attempt to understand the influence of basic structural parameters of fabrics on thermal protection and comfort, present study mainly focuses on analyzing effect of fabric weaving pattern and fabric weight. Fabric samples of three basic weaving patterns (plain, twill, and satin) and three different weights were prepared. Air permeability of the developed fabric samples was measured. Thermal protective performance of fabrics against radiant heat and flame exposures of two different intensities were measured. Spectral transmission behavior of fabrics was also studied. It was observed that for same fabric weight, protective performance and air permeability of satin woven fabrics were better as compared to the fabrics of other patterns. Protective performance increased and air permeability decreased as fabric weight increased for each type of woven structure included in this study. A new structural parameter is proposed which primarily influences the protective performance of fabrics exposed to either radiant heat, flame, or combined convective/radiant heat exposure.     

Characterization based on the thermal capabilities of metallized fabrics equipped with hybrid conductive yarns for protective clothing

Electronic textiles are recognized for their conductive characteristics in various fields of research including medicine, communications, power and for the development of protective clothing. Out of the several types of conductive textile available, multi-component yarns and fabrics, produced from continuous copper filament as spiral covering on hybrid cover yarns, have never been investigated for their thermal capabilities. In this study, characterization based on the thermal properties for conventional copper core yarn’s fabric and newly developed copper cover yarn’s fabrics was carried out. The results demonstrate better conductivity of copper cover yarn’s fabrics as compared to the copper core conventional fabrics, which is attributed to its better conduction due to greater percentage of copper and direct contact between the heat flux transducers. With the higher porosity values for the newly developed fabric, the liquid water, water vapour and air transport capabilities, which are key aspects of thermal comfort, significantly improved.     

Effect of compressibility on heat transport phenomena in aerogel-treated nonwoven fabrics

The heat transport properties observed in nanostructured materials such as aerogel-treated nonwoven fabrics are promoting revolutionary breakthroughs as thermal insulators. This article is focused on the thermal transport characteristics of nonwoven fabrics treated with aerogel for potential uses in thermal protective applications. Highly efficient aerogel thermal blankets are now considered a viable option in applications such as clothing, building, and pipelines. A variety of fiber and fabric structures or finishing parameters influence the functional properties of nonwoven materials. In order to assess the thermal properties of aerogel-treated nonwoven fabrics, the KES Thermolabo II and NT-H1 (plate/fabric/plate method for thermal conductivity, q_max cool/warm feeling, and thermal insulation) was used. Fabrics of higher thicknesses show lower heat conductance and therefore higher thermal insulation properties. It has been found that thermal insulation is also related to the weight and compressional properties of the fabric. To make an insulating material effective, it should have low compression set and high resiliency to make the still air to be entrapped into the fibrous material.     

灰色聚类分析在织物热学性能评价中的应用

为探讨酚醛纤维织物的热学性能,将酚醛纤维应用于消防领域,选取5种消防常用的织物聚酰亚胺织物、芳纶1313织物、芳纶1414织物、阻燃棉织物、碳纤维织物为研究对象,在相同条件下进行热学试验并将热导率、热扩散系数、比热、经向极限氧指数、纬向极限氧指数等作为研究指标,研究相同面密度的不同种类织物的热学性能。单一的指标对比不能综合评价出6种织物热学性能的优劣,利用灰色聚类分析理论对这5个指标进行聚类分析,对其热学性能进行综合评价。结果表明:酚醛纤维织物与聚酰亚胺织物具有较好的热学性能,芳纶1313织物的热学性能次之,芳纶1414织物、阻燃棉织物、碳纤维织物的热学性能最差。