衣下空气层对透气型防护服热阻和湿阻的影响

为确定适宜的服装宽松量,提升透气型核生化(NBC)防护服的热湿舒适性,设计了穿着实验。在温、湿度可控制的气候室内,借助出汗暖体假人和三维扫描技术,观察常温、静止状态下5套不同松量服装的热湿传递性能,探讨衣下空气层对NBC防护服热阻和湿阻的影响。研究结果表明:衣下空气层体积与平均厚度的增量变化相似,不同松量服装的衣下空气层对服装总热阻和总湿阻有显著影响;随着透气型NBC防护服松量的增大,服装总热阻随着衣下空气层的增加呈现先增后减的变化趋势,服装总湿阻随着衣下空气层的增加呈现逐渐增大的变化趋势。     

织物热阻和湿阻的预测研究

提出了利用织物常规性能预测织物的热阻和湿阻的方法，并指出了预测误差的大小。     

考虑内部辐射下织物热湿传递现象的数值研究

人体在着装情况下的热湿传递现象对人体的热舒适性的研究有着很重要的地位。考虑了由于温度差而引起的织物内部的辐射热传递，对织物中的热湿传递现象进行了数值研究，建立了考虑辐射现象下织物内部热湿传递的简单模型，并讨论了计算结果。     

单向导湿织物的开发

导湿快干织物最大的优点是符合人们对健康、舒适的消费需求。采用单面整理设计单向导湿棉织物,使其达到导湿快干的效果。整理后棉织物的热阻和湿阻相对于同规格的棉织物都有所下降,水或汗液从整理面导向织物另一侧时,能快速扩散、蒸发,使织物内层保持相对干爽。对织物进行耐摩擦和耐洗性测试,结果表明,整理后织物有很好的拒水耐久性能,即单向导湿具有持久的效果。     

湿阻法测试织物各向异性导湿性能

根据织物润湿后电阻的变化,以金属探针作为传感器,自制了1台织物各向异性导湿性能测试仪,该仪器可同时测试液态水沿织物经向、纬向及45°方向的导湿性能。试验结果表明:液态水沿织物扩散速率除了与织物品种、组织结构有关外,还和织物厚度、扩散方向等因素有关;液态水沿织物各向扩散位移的平方与扩散时间基本成线性关系。     

织物热湿传递性能及其评价

介绍了织物热湿传递舒适性能的主要指标如芯吸率、热阻值和湿阻值的各种测试方法的原理及其优缺点,并介绍了目前正在研制的能够测试织物纵、横向芯吸率且能同时测试热阻值和湿阻值的织物热湿舒适性测试仪。     

织物热湿性能的研究方法

介绍了用仪器测试法和数学模型预测法获得织物热阻和湿阻值的依据、原理及优缺点。指出仪器测试是从热阻和湿阻的定义出发设计实验装置并获得数据的;而数学模型预测法是从织物结构决定性能的角度,把织物热阻和湿阻与织物结构之间的关系归结为回归方程模型和神经网络模型来实现预测功能。     

具有开放衣下空气层的织物系统水汽传递性能

在M 261型织物透湿性能测试仪的基础上设计和搭建辅助装置,实现了对具有开放的衣下空气层的织物系统的水汽传递性能的测试。利用该装置对8种织物进行了衣下空气层厚度分别为4、8、12、16 mm和20 mm时织物系统的水汽传递性能测试。结果表明：在风速为0.03 m/s的条件下,在一定范围内,织物系统的水汽传递率随着衣下空气层厚度的增大而增大;衣下空气层厚度为4 mm时,织物系统的水汽传递率低于织物的透湿率;衣下空气层厚度为16 mm时,对于普通织物,织物系统的水汽传递率达到最大,比织物的透湿率高29.3%;衣下空气层厚度为20 mm时,对于防水透湿织物,织物系统的水汽传递率达到最大,与普通织物相比,织物系统的水汽传递率几乎没有差异。     

消防服多层织物的热湿舒适性

为研究消防员防护服面料的舒适性并考察织物组合舒适性的影响因素,选取我国消防服常用的11种织物,模拟消防服层次构成,即包括外层、防水透气层和隔热舒适层,进行多层织物热阻、湿阻和总热损失的测试与分析。结果表明:选取的几种织物组合,其基本性能均符合GA 10—2014《消防员灭火防护服》标准,但热湿舒适性与美国标准仍存在一定差距;织物的热阻、湿阻和总热损失均与其面密度有一定相关性,其中织物热阻、湿阻与面密度之间存在正相关关系,总热损失与面密度之间存在负相关关系;织物组合间空气层的厚度对织物组合的热阻值影响较大;织物组合总热损失与克罗值、透湿率之间的回归模型可直接用于评价消防服多层织物的热湿舒适性。     

出汗热护式热板仪系统的设计分析与试验研究

为了解出汗热护式热板仪的工作原理及相关测量标准,对国际上2种典型的SGHP和M259B出汗热护式热板仪的设计特点进行分析,对相关标准下特别是等温湿阻和不等温湿阻的测量原理进行阐述。使用SGHP-10.5型热板仪测量了20块面料的热阻、等温湿阻和不等温湿阻,结果发现,外气流层温度设定的差异对测量结果没有影响。在湿阻测量中发现,等温湿阻比不等温湿阻普遍大,均值高17.7%,推断在不等温湿阻的二步法测量中,假设面料在干湿2种状态下的热阻相同是造成误差的主要原因。与文献中使用M259B型热板仪的测量数据进行比较发现,空板数据差异巨大,推测M259B型热板仪相较SGHP-10.5型存在更大的系统误差。     

Study on thermal and evaporative resistances of multilayered fabric ensembles

The present work deals with the study on thermal and evaporative resistance of multilayered fabric ensembles meant for cold weather applications. Three-layered structure is used to study the thermal comfort properties. Knitted fabric and polytetrafluoroethylene coated fabrics were used in inner and outer layer, respectively. Needle punched fabrics produced from polyester fibre were used in middle layer. Fifteen different non-woven fabrics were produced according to Box and Behnken experimental design for three variables and three levels by varying mass per unit area, punch density and depth of needle penetration. The produced fabrics were evaluated for thermal and evaporative resistances with and without inner and outer layer fabrics. Thickness, air permeability, bulk density and porosity of the needle punched fabrics were studied. The properties of the fabrics were analyzed for statistical significance by using ‘Design-Expert’ statistical software. Artificial neural network model was developed to predict the properties of fabrics and validation of model was done with the testing data-set. The performance of prediction was evaluated by mean square error, mean absolute error percentage and correlation coefficient. It was concluded that the predicted properties of fabric correlated well with the experimental results.     

Statistical and ANN analysis of thermal and evaporative resistances of multilayered fabric ensembles

In this paper, thermal and evaporative resistance of multilayered fabrics meant for cold weather conditions have been reported. Polyester hollow fibers of 6 denier and 15 denier were used to produce needle-punched fabrics. Full factorial experimental design was used to produce 30 different needle-punched nonwoven fabrics from two different linear densities of fiber by varying mass per unit area and punch density at three and five different levels, respectively. The needle-punched nonwovens were used as insulative middle layer. Single jersey knitted fabric and polytetrafluoroethylene-coated fabric was used as inner and outer layer, respectively. The multilayered fabric ensembles were evaluated for thermal and evaporative resistance using sweating guarded hot plate (SGHP) system. Regression equations were developed to draw the contour plots and to analyze the effect of different parameters on thermal and evaporative resistance of fabrics. Two independent one-way analysis of variance (ANOVA) were conducted to find the significance of linear density of fiber and effect of inner and outer layers on thermal and evaporative resistance of fabrics. The two-way ANOVA was conducted to analyze the effect of mass per unit area and punch density on thermal properties of fabrics and ‘F’ values were calculated. Mean square values of pure error and lack of fit were studied to analyze the fitness of the developed model for thermal properties of fabrics. An artificial neural network (ANN) model was developed to predict the thermal and evaporative resistance of multilayered fabrics and compared with the experimental values. It has been observed that the ANN model predicts the thermal and evaporative resistance of multilayered fabrics with high degree of accuracy.     

The effect of moisture and air gap on the thermal protective performance of fabric assemblies used by wildland firefighters

The thermal protection performance (TPP) provided by fabric assemblies used by wildland firefighters is greatly affected by both the moisture and the air gap trapped in multilayer fabrics. In this paper, the effect of moisture, coupled with air gap on TPP was analyzed under radiant heat exposures of 21 kW/m². The air gap sizes from 0 to 5.2 mm were analyzed using an air gap height regulation device; the moisture content of the multilayer fabric combinations around 0–70% were obtained by spraying distilled water to simulate varying amounts of sweat absorption. The results obtained indicate that certain air gaps entrapped in multilayer fabric system have a positive effect on TPP for both dry and wet multilayer fabric combinations. However, obvious trend changes in thermal protection were observed among dry and wet configurations when the air gap was moved to different positions. For the wet configurations, the second-degree burn time increased as the air gap moved further from the heat source, which was contrary to burn time response under dry conditions. These findings suggest that the complicated reciprocal effect of air gap and moisture on thermal protection should be both considered in analyzing the TPP of fabric assemblies.     

蒸发冷却＋辐射供冷空调系统的设计

根据蒸发冷却和辐射供冷的热湿处理空调特性,利用焓湿图分配其热湿负荷．计算辐射供冷水侧的供回水温度、流量、供冷能力等．给出了蒸发冷却新风的送风状态点和送风量的求解结果,并给出了冷源设备的选型方法．     

服装及其面料热传递性能的测试与比较

新型织物模拟的暖体出汗假人能够测试服装的热阻和湿阻,传统平板式织物保暖仪可以测试各种纺织品热传递性能。采用这2种方法,对1组衬衣及其面料的热阻进行测试与比较。结果显示:平板保暖仪与暖体假人均具有较高的试验精确度和重现性,但暖体假人测试得到的服装及其附面层空气热阻与平板式织物保暖仪测试得到的织物及其附面层空气热阻有一定的差异。     

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。     

空气层厚度对热防护面料蒸汽防护性能的影响

为探索防护服装与人体皮肤之间的空气层厚度对其蒸汽防护性能的具体影响,选用3种不同热防护面料系统,设计4种不同的空气层厚度(0、6、12、18 mm),分析二级烧伤时间、三级烧伤时间、吸收总热量和热流量,评价面料系统的蒸汽防护性能。研究结果表明:不同的面料系统提供不同的防护性能,增加面料系统的厚度有利于提升其防护性能,防水透气膜越靠近蒸汽热源,系统的防护性能越好;防护服装的蒸汽防护性能与空气层厚度有着显著相关性,在空气层厚度增加到12 mm及以上时,防护服的蒸汽防护性能会得到显著提升;通过分析蒸汽暴露和冷却阶段传感器热流量变化曲线,可进一步分析了解蒸汽暴露环境下织物系统内的热湿传递机制。     

手臂活动角度对服装局部热阻的影响

为研究手臂活动角度对衣下间隙局部分布及服装局部散热性能的影响,利用三维扫描仪量化了出汗暖体假人在6种手臂姿势下,12个体段的衣下间隙体积及接触面积,提取了表征人体活动空间大小的物理指标,测量了服装各体段的局部热阻。结果表明:手臂的前伸角度与衣下间隙体积呈负相关性,而与接触面积呈显著正相关性,人体的活动空间随着手臂前伸角度的增加而显著减少;各体段的局部有效热阻呈现出非均匀的分布状态,局部衣下空气层体积越大、接触面积越小的体段,其有效热阻越大。服装的有效热阻可用衣下间隙体积与接触面积百分比共同预测。     

露点间接-直接蒸发冷却空调特性及换热分析

从热质交换和流体力学的角度分别对露点间接-直接蒸发冷却空调机组的结构和原理进行了分析.结果表明这种空调机组与传统露点间接蒸发冷却器相比,温降幅度大,可以进一步逼近室外空气的露点温度,是露点间接蒸发冷却技术的一个新发展.同时利用降液膜蒸发理论和界面汽化热阱效应对蒸发冷却传热传质过程的影响进行了分析,指出其对蒸发界面均起到强化传热的作用,进而加强了基于露点板式间接两级蒸发冷却空调机组的温降效果.