116.2翻译—在汽车中热化阶段和冷却阶段的热舒适性.pdf
外文翻译--在汽车中热化阶段和冷却阶段的热舒适性【中英文文献译文】
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郑州轻工业学院本科毕业设计（论文） 英文翻译题 目 在汽车中热化阶段和 冷却阶段的热舒适性 学生姓名 专业班级 学 号 院 （系） 指导教师(职称) 完成时间 18在汽车中热化阶段和冷却阶段的热舒适性在汽车中热化阶段和冷却阶段的热舒适性O. Kaynakli . E. Pulat . M. Kilic摘要: 大多数汽车有暖气通风和空调装置来控制车辆内部的热环境。但是在炎热或者寒冷的冬季里，从汽车启动到行驶稳定很难达到并且保持热舒适度，在这些过渡阶段，人类有体温调节程序领悟并促使冷暖系统改进和改良。这一项研究呈现出在汽车内部环境和人类身体之间的热交换作用的模型。模型基于人类身体的热平衡等式.和定义出汉率和皮肤表面平均温度的经验公式相结合，这种模拟已被短暂的情况下使用运行。汽车内部热化和冷却过程对热舒适度的影响已经被研究。结果跟现在的测量和文献资料中可获得的实验数据相符合。它表明实验数据和模型的协议结合非常好。符号目录A 表面区域,m2 热传导率，W 特性热,J/(kg K) 织物层的外部半径CSIG 寒冷信号 R 热或蒸发阻力，(m2 K)/W 或者 (m2 KPa)/W 修正常数 S 储蓄热，W 传热系数,W / (m2 K) t 时间,s (除非在数分钟内指定) 片段系数 温度， 空气或织物层数 热感觉 传导的传热系数,W/ (m K) 空气流速，m/s 热负荷, W / m2 皮肤湿度 身体块,kg 湿气比，kg H2O/kg dry air 每单位区域块流程率；kg / (s m) 外部工作完成速率，W 热量制造的新陈代谢率；W WSIG 温暖信号nl 分层的数量 厚度，mm 水蒸气压力；KPa希腊符号 皮肤层块与身体总块的比率 渗透效率 下标数字a 空气 ex 呼气al 空气层 f 织物b 身体 int 外部衣物表面和固体的界面（例如座位或靠背）bl 血液 max 最大值cd 传导 n 中间的cl 衣服 rex 呼吸cr 核心 rd 辐射cv 对流 s 饱和的dif 散布 sk 皮肤e 易受到对流和辐射的环境 sw 汗液ev 蒸发 t 总数1介绍一辆汽车的司机和乘客的舒适感部分取决于车辆内部空气的质量和温度，三个相关的系统被用于提供所需求的空气温度和质量。这些是通风系统，暖气通风和空调系统。一辆车的暖气通风和空调系统的作用是为它的乘坐者提供完全的热舒适。因此，非常必要去了解人身体的热量方面的情况，以便设计一个的效的HVAC系统。为了估计热舒适水平，环境热量方面的准确信息是必需的。环境热量能概略地被汽车内部的空气温度、速度和湿度表现。在交互作用中，热量和传质一起发生。完成人类舒适的模型包括能量平衡液体和材料热力性能相等，热量和传质特性，一辆汽车的乘客坐的车厢在冬季中被通过冷却剂-空气的热交换器的循环热引擎冷却加热以使车厢的空气暖和。加热系统被设计成与空气流通系统一同操作，以便能提供所需的温度。随着引擎大小的改进变小，从燃料的经济方面和车辆加热系统的可利用热量相应地减少方面考虑，从考虑市场情况出发为确保乘客的热舒适感，甚至在极端的情况下，有一种发展更有效的系统的兴趣为达到并保持乘客的热舒适感是很困难的。一些辅助的加热或冷却装置或许极大地减少了需要达到热舒适的时间，但是这个装置的能量需求是很大的。 在严热的季节，空调被应用。当提起空调装置时。脑海里第一个想法是冷却和清爽的空气。事实上汽车空调系统不仅冷却空气而且清洁、除温使空气流通以使乘客健康舒服，这些程序同加热和通风系统一起运行。 人类的热舒适感早被认为是先前的研究课题，有许多被证明和编成法典的可利用的数据3。在文献中，大多数研究考虑热量状况几乎一致完整地覆盖乘客的整个身体。在乘客身体被很不均匀和短暂覆盖的状况下比较少的注意出现在指向在同一汽车内的热舒适。Yigit18计算了每一个身体部分的热损失和穿五件不同套装时整个身体的热损失。然而身体各个部位的热损失没有被考虑，衣物阻扩抗对台戏热舒适的影响也没有被估计。Mccullough et al13，14出版了绝缘价值，典型的衣服套装蒸发与热力模型对比。这些参数也被用于测量使用热力装置加湿的部分织物。一个计算机模型被开了出来用于估计热传递中干燥和蒸发空气的阻力。Olesen et al.15研究了五套具有相同全部热力绝缘的不同衣服套装，但是对16个静止不动的实验主题实验是知身体的上部分到下部分排列，他们的实验研究将会给测量衣服套装的热阻不均匀提供一个方法，并且检查它是如何影响使当地热量不稳定。Tanebe et al.16，用一个模型调查了人体几个部分有感觉的潜伏的热损失。对于身体上每一个考虑过的部分，总的热传递系数和热阻力被出现。既使他们的研究是在封闭的环境中进行，它没有提供任何热舒适的结果。Kaynakli et al.11报告一顸研究说人类身体被分成16个部分，在每一个16个身体部位和环境之间热交互的计算机模型被开发出来。随着模型的使用，坐着和站着时身体的各个部分和整个身体的皮肤湿润情况和潜在（蒸汗蒸发，扩散）和有感觉的（传导、对流、辐射）的热量损失被计算出来。Kaynakli et al. 12呈现人体和环境间和质量传递的数学模型。在他们的研究中，人们在不变的情况下获得满足感所需的环境的个人状况和总计的有感觉的和潜在的热损失，皮肤温度、出汉、预测的平均赞成率（PMV）和预测的不满意百分比（PPD）的价值经由模型被计算出来 。Chakroun和Al-Fahed7研究了一辆在科威特夏季数个月内停在太阳下的一辆汽车的温度变化和热舒适性。他们也认为在汽车内部用不同的内部材料混合物对温度有影响。Burch et al.4报告了在严寒冬季升温时期的驾驶状况下的一系列关于乘客热舒适性的试验结果。他们发现安装在座位和靠背上的小功率电力加热设备极大地减少升温时间可以综合通过在空气管道中安装电加热器实现，虽然与这种方法有关的能量需求是很大的，除了他们的实验研究之后。他们将关于这个课题的一项分析研究发表在Burch et al.5。汽车启动时加热和降温期间需要一些时间达到稳定的状况。在这些时期，乘车者身体热量分布十分不均。乘客感觉局部寒冷归究于与一个最初的凉座位或于车轮接触与环境不均匀的辐射热传递，局部太阳照射和空气调速器的位置，仪表板控制的设定所决定的不均匀的空气速率有关。因此为了达到保持汽车内乘客的热舒适性的技术发展中产生了很大兴趣。这项研究呈现一个人类与汽车内环境之间热交互的模型。因此部分分析认为局部不舒服是由在一个相对狭小空间内。衣服隔热不均匀造成的。比如汽车车厢内。现在的模型是基于被分成16部分的人体的热力平衡相等结合Gagge et al.s10和Olesen et al.s15的方法，所有身体部分被看作是二同心圆筒，需要背后数据比如身体部分的表面积，它们质量从现有文献中提取，这样，除了gagge et al.s10 的模型，尽量通过计算身体各个部分的热交换和皮肤温度，出汉率来定义局部不舒适性。在短暂的情况下模拟被运行应用。汽车内部加热和降温过程对舒适性的影响已经被证明。实验也指导了冷却周期，直到汽车达到热舒适性，温度和温度才发生改变。司机和乘客被这些变化极达地影响，为证明现在的模型，模拟结果和实验做了比较。2 数字模型从乘客上面流过的环境空气的速度从小空间热舒适性观点来说非常重要，因为它有很大的加热和降温能力，例如在汽车车厢内，在司机和乘客上方流动的空气进入衣服开衩口对于任何乘客身体没有相同作用。虽然对于典型户内状况取代平均速度是好的近似值，但以汽车内部看来结果会产生很大的错误。坐着的乘客身体上方局部空气流速被Burch et al.5 （表1）经实验列出。在这项研究中，测定乘客身体各部分热损失的因素基于这些速度值。在这项研究中用的模型是基于Olesen et al.15中描述的方法。在这项研究中为了证明冬天和夏天条件下，环境热量对于乘客坐者尤其是司机详细的影响，考虑身体上衣服和当地空气流速的影响人体被分成16部分。在表2中，表面积和他们身体表面积的各小部分都已给出。用身体各部分储存的能量来计算当时，温度变化许多这些身体部分大量的身体部分和他们身体的保各个小部分见表3。将人体视作一个整体，从热舒适性观点看平均皮肤温度是个不主意，但是四肢例如：手、脚和脸或者裸露和身体部分的温度可能增加或减少不必要的数值。通过使用发展了的模型，影响热舒适性的每一个身体部分的有感觉的和潜能在热损失的参数变化的时间率，皮肤温度和皮肤出汗率可能被研究。21人类身体的热力和生理学模型两包厢间过渡性热量平衡模型被Gagge et al.10发明，将身体描述成两个同心圆筒，里面的圆筒代表身体核心（骨骼、肌肉、内脏）另外一个圆筒代表皮肤层。这个模型考虑到核心和皮肤部分即时的热量储存，假定这些部分的温度随时间变化。这个热力模型用一对热力平衡等式来描述，其中一个适用于任何部分3：式子中，代表热力产生的新陈代谢率，代表机械工作的熟练程度，呼吸的热损失率，热量从体内到皮肤的传输率，, , 从皮肤层到环境分别以传导对流和辐射方式的热损失率，和表示在体内和皮肤层储存的能量在为些部分引起的瞬时温度改变。这些效果可用下列等式表示：代表身体部分质量，代表身体特有热量。和出现在等式2中代表对流和辐射和热传递，可用下列关系计算：式中，是暴露到环境中的身体部分的外表面积总面积除去与座位接触的面积，靠背面积等等）代表穿衣服的身体部分与裸露的身体部分表面区域的比率包括平均辐射和周围空气温度如下所示：热辐射传热系数取值4.7n/(m2.k)是因为它用于内部状况足够精确3身体各部分的对流热传递数在de Dear et al.8中取值。由于皮肤总的潜热损失来自蒸发, 表示为：式中, 是蒸发比率, 是皮肤温度的饱和水蒸汽分压力, 是环境空气的水蒸汽分压力, 是衣物的浸透高效率,LR是蒸发热传递与对对流热传递系数的比的路易斯系数.McCullough et al.14已经发现通常室内衣物浸透系数平均值=0.34总皮肤的潮湿度(),包括常规出汗引起的和通过皮肤扩散的湿度,均由下列式子给出.最大的蒸发潜能,当皮肤表面完全浸湿(=1)时, 出现.在一辆汽车中身体表面的重要部分(1520%)是由座位,靠背和方向盘接触的,这部分不是认为以对流、辐射方式散失热量.由于皮肤热传导的热损失由下式给出：在两个节点模型中,身体中心和皮肤间的热交换由通过直接接触和皮肤血液流动发生的。身体的平均热电导常量被假定为=5.28W/(m2 k)从身体中心到皮肤的热流动如下式：血液的特定热，是4.187J/(kg k)呼吸热损失大约是总热损的10%,呼吸热损失大约是总热损的10%。由于呼吸的热损失如下式：式中是吸入空气的流动率, 和分别是出气温度和周围空气温度。和分别是呼气和周围空气的湿气比.蒸发的热量是2.43106J/kg.皮肤块与总身体块的比率()被当作身体核心的下述功能与皮肤中血液流动的比的模型:每单位皮肤面积内核心到皮肤的血液流动被表示成:每单位皮肤区域的出汗率被估计为:人体平均温度能通过皮肤到核心的重要平均温度预测:身体中间温度能用同样方法通过皮肤到核心的中间温度计算.身体被分成16个统一穿衣物的部分.每个部分的总热阻和总蒸发热阻如下各项.假定通过空气层和衣物层的热传递是以传导和辐射方式发现,在这种情况下空气层的热阻如下式:式中,Xa是空气层厚度, Hrd和k的数值是Hrd=4.9(k)和k=0.024W/(mk)14蒸发热阻也能写成相似的等式.空气层的蒸发热阻如下式:式中a和b是常数.a和b的数值分别是0.0334(kpa)/W和15mm14裸露在环境中的外表面处理的有一点不同.外层的热阻为:外层的蒸发热阻通过对流的热传递系数和路易斯关系决定:2.2 热感觉的预测上述等式描述了人体环境和温度调节装置间的热交换.身体E热能量热负荷的组合,影响在身体与环境间热量交换中的人热舒适性.如果身体的热负荷(L)几乎是零,中间状况或热舒适性就达到了.运动.衣服和四个环境系数(气温,平均发光温度,空气流速和湿度)的组合都影响热舒适性.应用最广泛的热舒适参数是热感觉(TS),数值在式27中给出式中,Ab是身体的总表面积,表4 给出了TS的比值.2.3 假定和起始状况裸露的身体表面积取为Ab=1.75/,体重是80千克,核心和皮肤的初始温度值分别取为36.8和33.7夏季衣物隔热率,冬季衣物隔热率,夏季衣物的衣服面积因素,冬季衣物的衣服面积因数和活动的新陈代谢率分别取为:0.5clo,1.5clo,fcl=1.1,fa=1.15和75W/.5,6身体上的局部空气速度在表1中给出,加热和冷却过程的平均空气温度(Ta)见图1和图2,加热阶段相关的温度取0.355,冷却阶段见图3,平均辐射温度在加热阶段取为在冷却阶段取为在加热阶段与身体(Tint)接触的物体的表面温度(t从起动开始的以分钟计的时间)如下式座位:与座位接触的穿衣物的身体面积:0.07.靠背:与靠背接触的穿衣物的身体面积:0.07.方向盘:与方向盘接触的穿衣物的身体面积:0.01.在冷却阶段,发现身体有接触物体的表面温度(Tint)与运行实验（t是以分钟计）的结果一样（表5）。3 结果与讨论为了证明加热和冷却过程对汽车内部状况的影响，数学模型部分中的等式运用Delphi6系统语言来指导计算机媒体。在加热阶段，需要靠背和方向盘表面温度都取自Burch et al.5，在他们的实验研究中，内部空气已经被从-20加热到20，如图1所示。冷却过程所需要的实验数据在1991年装有一个2000-cc引擎的丰田汽车被测量。汽车停在日光下，观察到车内气温上升到64，周围环境温度大的是30。稍后，标准的冷却程序随空调器的启动而开启。在这个过程中，车内温度，相关的温度，座位，靠背和方向盘表面温度被测量。测量的参数见图2和图3。因为在汽车内温度升到64时相关的湿度从50减少到11，所以在冷却阶段相关湿度从11开始。在升温过程中从身体到环境的热损失在图4中相比较地给出。因为Burch et at.5的模型和现在的模型存在一些原则上不同（例如：在Burch的模型中身体被分成4个部分，但在我们的模型中身体被分成16个部分），故一些差别在开始阶段出现。除去这些相对小的时间间隔，结果间达成的一致也在可接受的范围内。由于与物体表面接触的身体各部分的面积小于其它身体表面积，故座位、靠背和方向盘的传导热损失与总的对流和辐射热损失相比相当低。在升温过程的开始阶段，因为汽车内温度和内部表面温度相当低，传导、对流和辐射的热损失很高。甚至这些总的热损失比热力过程中的新陈代谢高。因为这个原因，身体核心和皮肤温度有一点减小。但是皮肤温度的减小要比核心温度减小的多。显然这些热损失的快速减小归究与汽车内温度的升高。在这个过程中，身体试图保持最小限度的呼吸和蒸发热损失以便平衡热损失。升温阶段相对比的变化的Ts值见图5，通过图5的验证，与Burch et at.5有一个好的相吻合处。 这些计算在和分析研究中运行。在他们的实验中，Ts的数值由参考数据获得，平均热舒适性和参考数据的标准偏差通过时间计算。现在研究计算结果在Ts16范围内，的值取0.62。最初，从身体到环境的时间热力损失由于汽车内的低温度缘故一直很高。因此，由于内部温度和外表面温度升高，热舒适性得到改善。指出汽车车厢升温阶段环境状况对人舒适的影响的一个参数是身体表面平均温度和它随时间的变化见图6。在最初几分钟内，由于车内和物体内部都很低的温度，平均皮肤温度立即下降。随着车内温度随时间而升高，在它的值降低到一个最小值32后平均皮肤温度开始升高。虽然平均表面温度对人类舒适状况是一个好的信息，但也必须注意人体的局部不识。和固体表面接触的身体背部、大脚和手的温度在图7中给出。内部温度对背部背部和脚的温度影响不大，故它们的变化不重要。但是手面的温度减小到17.5可以被估计为一个相当低的温度。在文献中，提到当手面温度达到20时引起认为不舒服的寒冷，达到15就极其寒冷3。在冷却过程中身体上的热传递见图8。由于在开始车内温度和表面内部温度很高，有感觉的热流动（传导、对流、辐射）从环境到人体发生。这种情况导致从身体内部到皮肤温度的升高。为继续维持身体重要功能和另外确保舒适的状况，从环境对身体的热量和热力过程的新陈代谢热量必须被排放到环境中。因此，身体增加了出汗的次数，很快身体的很大部分被汗覆盖。这样，蒸发热损失的增加见图8。然而呼吸热损失不受环境状况的影响，它保持在大约10W。 Chakroun和 Al-Fasheds7的研究中，冷却阶段的热舒适性的变化分别在图9中给出。在Chakroun和 Al-Fasheds7的书中，详细的环境状况没有给出，所以我们的模型无法直接应用于他们的测量状况。因此，这一个图只是一个性质上的比较。在他们的研究中，可以肯定停在太阳下的汽车内部温度达到大约65。然后，冷却程序通过操作A/C开关研究调查。但是在相当热的气候中进行而环境温度是45。然而在我们的实验中它是30。太阳的辐射也比我们的情景下强。由于这个原因，汽车内描述的温度是不同的，所决定的Ts值也不一样。在最早的几分钟内，由于车内高温，热量通过传导，对流和辐射从环境传到人体。因此，由于身体有一个明显的热负荷，Ts有一个很高的初始值。然后，热负荷随车内温度减小而减小，表面温度和舒适状况得到改善。冷却过程中身体、脚和手面平均温度的变动见图10。但是，直接与空气接触的手的温度的升高比其它部分大。随着车内冷却时间变化，这个温度升高度下降。手部最易受到环境状况的影响，所以温度的明显减小呈现在手上。相似的情形对头部来说也很有效。既然鞋子是重要的隔热元素，脚没从内部温度变化受到影响。由于这一原因，在冷却过程最后最高的温度出现在脚部。身体的平均表面温度在手和脚的温度间改变。 改变舒适感的一个重要参数是皮肤湿度，它随着时间的变化见图11。在冷却过程的初始阶段，由于车内温度高，出汗率增加，以便增加身体的热损失。因此皮肤的湿度增加。由于鞋子缘故，最快的增加发生在脚部。由于头部没有衣物阻止出汗的蒸发，手臂不与方向盘接触，皮肤湿度在这些身体部分中最低，然而平均身体表面湿度在头部和脚部湿度中间升高到最大值0.6。4 结论在这项研究中，介绍了内部环境状况对人类生理学和加热和冷却过程对舒适性的影响。表示体温控制装置的基本热交换等式和经验关系被用于人体与环境间的热质传递。在这些过程中，考虑到车内温度和相关湿度和与身体接触的物体表面的温度，热传递的变化，身体部分表面温度和湿度和Ts数值都给了出来。 在升温阶段的最初几分钟，由于车内和表面的低温，从身体到环境的热损失很大。在这个时期，蒸发热损失通过体温调节装置保持在最小值。身体的平均皮肤温度降到32，与方向盘接触的手温也降到一个很低的值17.5。由于从身体到环境的热损失变得很重要，Ts值从-4.5开始，然后随内部温度升高，它开始得到改善。 在冷却阶段的最初几分钟，和升温阶段相反，由于车内和表面高温，感觉热交换从环境到身体间发生，由于这个原因，Ts值从一个相当高的值8开始，然后随内部温度升高而下降。为了平衡身体与环境间的热交换，出汗过程增加，所以潜在热损失增加。考虑到升温和冷却阶段的呼吸热损失都不受环境状况的影响，随着出汗过程增加，身体皮肤湿度增加，由于衣服热绝缘度高，身体表面的皮肤湿度很高，相反，裸露的身体表面（例如头和手）很低。同理，这些裸露的表面也是受环境状况影响最快的部分。除此之外，也提到了只有一名司机在车内的停着的汽车的测量结果。汽车内无人或汽车内有乘客都可能影响测量结果。参考文献1 Althouse A (1979) Modern refrigerations and air conditioning,The Goodheart Willcox Company, USA2 Arc O , Yang SL, Huang CC, Oker E (1996) A numerical simulation model for automobile passenger compartment climate control and evaluation. In: International energy and environment symposium, Turkey 2931 July, pp 108110873 ASHRAE (1993) ASHRAE handbookfundamentals, chapter 1. Atlanta: American society of heating, refrigeration and airconditioning engineers, p 344 Burch SD, Pearson JT, Ramadhyani S (1991) Experimental study of passenger thermal comfort in an automobile under severe winter conditioning. ASHRAE Trans 97: 2392465 Burch SD, Ramadhyani S, Pearson JT (1991) Analysis of passenger thermal comfort in an automobile under severe winter conditioning. ASHRAE Trans 97: 2472576 Butera FM (1998) Chapter 3Principles of thermal comfort. Renewable Sustainable Energy Rev 2: 39667 Chakroun C, Al-Fahed S (1997) Thermal comfort analysis inside a car. Int J Energy Res 21: 3273408 de Dear RJ, Arens E, Hui Z, Ogura M (1997) Convective and radiative heat transfer coefficients for individual human body segments. Int J Biometeorol 40: 1411569 Fanger PO (2001) Human requirements in future air-conditioned environments. Int J Refrigeration 24: 14815310 Gagge AP, Stolwijk JAJ, Nishi Y (1971) An effective temperature scale based on a simple model of human physiological response. ASHRAE Trans 77(1): 24726211 Kaynakli O, Unver U, Kilic M (2003) Evaluating thermal environments for sitting and standing posture. Int Commun Heat Mass Transfer 30(8): 1179118812 Kaynakli O, Unver U, Kilic M (2003) Calculation of thermal comfort zones with the ambient parameters. IEEES-1 the first international exergy, energy and environment symposium,Izmir, Turkey, July 1317, pp 76977313 McCullough EA, Jones BW, Huck J (1985) A comprehensive data base for estimating clothing insulation. ASHRAE Trans 91(2): 294714 McCullough EA, Jones BW, Tamura T (1989) A data base for determining the evaporative resistance of clothing. ASHRAE Trans 95(2): 31632815 Olesen BW, Hasebe Y, de Dear RJ (1988) Clothing insulation asymmetry and thermal comfort. ASHRAE Trans 94(1): 325116 Tanebe S, Arens EA, Bauman FS, Zang H, Madsen TL (1994) Evaluating thermal environments by using a thermal manikin with controlled skin surface temperature. ASHRAE Trans 100(1): 394817 Winter DA (1979) Biomechanics of human movement. Wiley, Toronto18 Yigit A (1998) The computer-based human thermal model. Int Commum Heat Mass Transfer 25(7): 96997720ORIGINALO. Kaynakli E. Pulat M. KilicThermal comfort during heating and cooling periods in an automobileReceived: 9 September 2003/Published online: 17 September 2004? Springer-Verlag 2004Abstract Most vehicles have a heating, ventilation andair conditioning (HVAC) device to control the thermalenvironments of interior of the vehicle. But, under hotsummer season or cold winter conditions, it is difficult toachieve and maintain thermal comfort in an automobilefrom the start up to the steady-state conditions. Duringthese transition periods, an understanding of humanthermoregulatory processes facilitates the design anddevelopment of improved heating and cooling systems.This study presents a model of thermal interactionsbetween a human body and the interior environment ofan automobile. The model is based on the heat balanceequation for human body, combined with empiricalequations defining the sweat rate and mean skin tem-perature. Simulation has been performed by the use oftransient conditions. The effects of both heating andcooling processes on the thermal comfort inside theautomobile are investigated. Results are compared withthe present measurements and available experimentaldata in the literature. It is shown that the agreementbetween the experimental data and the model is verygood.List of symbolsAsurface area, m2cpspecific heat, J/(kg K)CSIGcold signalfcorrection factorhheat transfer coefficient, W/(m2K)isegment numberjair or fabric layers numberkconductiveheattransfercoefficient,W/(m K)Lheat load, W/m2mbody mass, kg_ mmass flow rate from per unit area, kg/(s m2)Mmetabolic heat production rate, Wnlnumber of layers covering segmentpwater vapor pressure, kPaQheat transfer rate, Wrouter radius of fabric layerRthermal or evaporative resistance, (m2K)/Wor (m2kPa)/WSheat storage, Wttime, s (unless specified in minutes)Ttemperature,?CTSthermal sensationVair velocity, m/swskin wettednessWhumidity ratio, kgH2O/kg dry air_ Wexternal work rate accomplished, WWSIGwarm signalxthickness, mmGreek symbolsaratio of skin layer mass to total body massgpermeation efficiencySubscriptsaairalair layerbbodyblbloodcdconductionclclothingcrcorecvconvectiondifdiffusioneexposed to convective and radiant environmentevevaporationO. Kaynakli E. Pulat M. Kilic (&)Faculty of Engineering and Architecture,Department of Mechanical Engineering, Uludag University,Gorukle Campus, 16059 Bursa, TurkeyE-mail: .trTel.: +90-224-4429183Fax: +90-224-4428021Heat Mass Transfer (2005) 41: 449458DOI 10.1007/s00231-004-0558-9exexhaledffabricintinterface between outer clothing surface and asolid (such as the seat or back support)maxmaximumnneutralresrespirationrdradiationssaturatedskskinswsweatttotal1 IntroductionThe comfort of the driver and passengers in a vehicle ispartially dependent on the quality and temperature ofair in the vehicle. Three interrelated systems are used toprovide the desired air temperature and quality. Theseare the ventilating system, the heating system and the airconditioning system. The purpose of the heating, venti-lation and air conditioning (HVAC) system of a vehicleis to provide complete thermal comfort for its occu-pants. Hence, it is necessary to understand the thermalaspects of the human body in order to design an effectiveHVAC system.In order to estimate the thermal comfort level,accurate information on the thermal environment isessential. The thermal environments can be roughlyrepresented by the temperature, velocity and humidity inthe automobile interior. In this interaction, heat andmass transfer take place together. Complete model ofhuman comfort consist of energy balances, equations forthe thermophysical properties of the fluids and materi-als, and heat and mass transfer characteristics.The passenger compartment of an automobile isheated in the winter months by circulating hot enginecoolant through a coolant-to-air heat exchanger thatwarms the compartments air. The heating system isdesigned to operate in conjunction with the air venti-lating system to provide the desired air temperature.With progressive reductions in engine size, stemmingfrom considerations of fuel economy, and correspondingreductions in the heat available for the passenger heatingsystem, there is interest in the development of moreeffective systems to ensure passengers thermal comforteven in extreme conditions by considering market situ-ation. It is difficult to achieve and maintain passengerthermal comfort under extremely hot or cold drivingconditions. Some auxiliary heating or cooling apparatusmay greatly reduce the time needed to attain thermalcomfort. But, power requirements associated with thisapparatus are substantial.In hot season, air conditioning units are used. Whenair conditioning is mentioned, the first thought thatcomes to mind is cooling and, refreshing of air. Actually,the automobile air conditioning system not only coolsthe air but also cleans, dehumidifies, and circulates itfor the health and comfort of the passengers. Theseprocesses are performed by working in conjunction withthe heating and ventilating systems.Human thermal comfort has been the subject ofconsiderable previous study, and much of the availableinformation documented and codified 3. In the litera-ture, most of the studies have considered the thermalconditions are nearly uniform and steady over the entirebody of occupant. Less attention appears to have beendirected to comfort in an automobile, where conditionsare highly nonuniform and transient over the body ofthe occupant.Yig it 18 is to calculate the heat loses for each bodysegments and total loss for the whole body for five dif-ferent clothing ensembles. However heat losses from theparts of the body were not considered and clothingresistances were not evaluated for the thermal comfort.McCullough et al. 13, 14 published the insulationvalue, evaporative resistances of representative cloth-ing ensembles that were measured with a thermalmanikin. These parameters were also measured forcomponentfabricsusingasweatinghotplateapparatus. A computer model was developed thatestimates the resistance to dry and evaporative heattransfer. Olesen et al. 15 studied five different cloth-ing ensembles with the same total thermal insulation,but very different distributions of the insulation on thebody in experiments with 16 sedentary subjects. Theasymmetry was ranging from nude upper part to nudelower part of the body. Their experimental study willprovide a method for quantifying the nonuniformityof a clothing ensemble and examine how it influenceslocal thermal discomfort.Tanebe et al. 16, investigated sensible and latentheat loss from several parts of the human body by theuse of a manikin. For each considered part of thebody, total heat transfer coefficient and thermal resis-tance were found. Since their study was performed inconstant temperature environment, it did not give anyresult about the thermal comfort. Kaynakli et al. 11reported a study in which the human body is dividedinto 16 sedentary segments, a computational model ofthermal interactions between each of 16 body segmentsand the environment is developed. By the use of themodel, skin wettedness and latent (sweating, diffusion)and sensible (conduction, convection, radiation) heatlosses from each body segment and whole body arecalculated for both sitting and standing postures.Kaynakli et al. 12 presented a numerical model of theheat and mass transfer between the human body andthe environment. In their study, the required environ-mental and personal conditions for satisfaction of thepeople obtained under steady-state conditions, andtotal sensible and latent heat losses, skin temperature,wettedness, predicted mean vote (PMV) and predictedpercentage of dissatisfied (PPD) values were calculatedvia simulation.450Chakroun and Al-Fahed 7 presented a study ofthe temperature variation and thermal comfort insidea car parked in the sun during the summer months inKuwait. They also considered the effect of using dif-ferent combinations of internal covering on the tem-perature inside the car. Burch et al. 4 reported theresults of a series tests on passenger thermal comfortduring warm-up under severe winter driving condi-tions. They found that low-power electric heating padsinstalled on the seat and back support greatly reducethe time needed to attain thermal comfort. Furtherreductionsinwarm-uptimecanbeachievedbyinstalling electric heaters in the air ducts, although thepower requirements associated with this method aresubstantial. In addition to their experimental study,they presented an analytical study on this subject inthe paper of Burch et al. 5.Heating and cooling periods from the start up ofthe vehicle require some time to reach steady-stateconditions. During these periods, conditions are highlynonuniform over the body of the occupant. Thevehicle passenger experiences localized chilling due tocontact with an initially cold seat or steering wheel,nonuniform radiant heat transfer with the surround-ings, localized solar irradiation, and nonuniform airvelocities that vary depending on the location of theair registers and dashboard control settings. Thus, inaddition to the air temperature, several other factorshave a bearing on the thermal comfort of the pas-senger. Consequently, there is substantial interest inthedevelopmentofmoreefficienttechniquesforachieving and maintaining passenger thermal comfortin an automotive environment.This study presents a model of thermal interactionsbetween a human and the interior environment of anautomobile.Since,segmentalanalysispermitsthedetermination of local discomforts by considering theclothing insulation asymmetry effects in the relativelysmall volumes such as automobile cabin, the presentmodel is based on the heat balance equation for humanbody by dividing it into 16 segments. By combiningGagge et al.s 10 and Olesen et al.s 15 approaches,all body segments are considered as two-concentriccylinders and required new data such as surface areasof body segments and their masses are refined from theexisting literature. In this way, apart from the Gaggeet al.s 10 model, it is tried to determine the localdiscomforts by calculating the thermal interactions ofeach segment and the skin temperature and wettedness.Simulation has been performed by the use of transientconditions. The effects of both heating and coolingprocesses on the thermal comfort inside the automobileare investigated. Experiments were also conducted forcooling periods. Until the thermal comfort reached inthe automobile compartment, the temperature and thehumidity changed dramatically. Driver and passengersare greatly affected by these changes. The simulationresults and experimental data were compared, in orderto validate the present model.2 Mathematical modelThe velocity of conditioned air that flow over passengeris very important from comfort point of view in smallcompartments that have large heating and coolingcapacity especially such as automobile cabin. Flowingair over driver and passengers injected by inlet vents hasnot same value on any occupants body. Although it is agood approximation to take average velocity for typicalindoor conditions, this results important mistakes byconsidering automobile interior. Local air velocities onthe body of sitting passenger were determined experi-mentally by Burch et al. 5 (Table 1). In this study,determination of heat losses from various regions ofpassenger is based on these velocity values.The model used in this study is based on the sameapproach described in the study of Olesen et al. 15. Inthis study, human body is divided by 16 regions byconsidering clothing groups and local air velocities onthe body in order to investigate the effects of thermalenvironment to occupants especially driver in detail forboth winter and summer condition. In Table 2, surfaceareas and their fractions of total body surface area aregiven.To compute temporal temperature variations byusing stored energy in the body segments it is requiredthe masses of these segments. The masses of body seg-ments and their fractions of the total body mass areshown in Table 3.By considering the human body as whole, mean skintemperature gives an idea from thermal comfort point ofview but the temperatures of the extremities such ashand, foot and face or naked parts of human body mayincrease or decrease unwanted values. By using thedeveloped model, time rate of changes of the parametersthat affect the thermal comfort such as sensible andlatent heat losses each of 16 regions, skin temperaturesand skin wettedness may be examined.2.1 Thermal and physiological modeling of human bodyA two-compartment transient energy balance modeldeveloped by Gagge et al. 10 represents the body astwo concentric cylinders the inner cylinder represents theTable 1 Local air velocities on the body 5RegionAir velocity(m/s)Head0.13Trunk0.11Right shoulder0.12Left shoulder0.13Legs0.11Right knee0.18Left knee0.21Right ankle0.66Left ankle0.62451body core (skeleton, muscle, internal organs) and theother cylinder represents the skin layer. This model, byconsidering instantaneous heat storage of the core andthe skin compartment, assumes that temperatures ofthese compartments change with time. The thermalmodel is described by two coupled heat balance equa-tions, one applied to each compartment 3:Scri Mi ? 7pt _ W i ? Qresi Qcr;ski?1Sski Qcr;ski ? Qcdi Qcvi Qrdi Qevi2where, M rate of metabolic heat production, 7pt _ W rateof mechanical work accomplished, Qrestotal rate ofrespiratory heat loss, Qcr,skrate of heat transport fromcore to skin, Qcn, Qcv, Qrdrate of heat loss from skin toenvironment by conduction, convection and radiationrespectively. Scrand Sskthat denotes stored energies incore and skin layer causes instantaneous temperaturechanges in these compartments. These effects are ex-pressed with following equations:dTcridtScri1 ? a micp;b?3dTskidtSskiamicp;b?4where m is the body segment mass, cp,bis the specificheat of the body. Qcvand Qrdterms in Eq. 2 are the heattransfers with convection and radiation and can be cal-culated with following relation:Qcv Qrdi Tski ? Toi AeiRcli 1=hcvi hrd fcli?5where, Aeis the surface area of the body segmentsexposed to the environment (total area minus the area incontact with seat, back support, etc.), fclis the ratio ofthe surface areas of the clothed body and the nude body.Operative temperature value (To) that includes averageradiation and ambient air temperature is given asfollows:Toi hrd?Trd hcviTahrd hcvi6For radiative heat transfer coefficient the value of4.7 W/(m2K) is used since it is sufficiently accurate forinternal conditions 3 and convective heat transfercoefficient values of each segment of the body are takenTable 2 Surface areas of the body segments 15Body segments Segment number Surface area m2 Fraction of total body surface area % Left foot 10.062 3.5 Right foot 20.062 3.5 Left fibula 30.140 8.0 Right fibula 40.140 8.0 Left thigh 50.160 9.1 Right thigh 60.160 9.1 Pelvis70.0804.6Head80.18010.4Left hand 90.050 2.9 Right hand 100.050 2.9 Left forearm 110.062 3.5 Right forearm 120.062 3.5 Left upperarm 130.077 4.4 Right upperarm140.077 4.4 Chest150.18510.6Back160.20411.7The whole body 1.751 100.0 Table 3 Mass of the body segments 17BodysegmentsSegmentnumberMass(kg)Fraction of totalbody mass (%)Foot121.161.45Fibula343.724.65Thigh568.0010.00Pelvis76.788.48Head86.488.10Hand9100.480.60Forearm11121.281.60Upperarm13142.242.80Trunk151632.9841.22The whole body80.00100.00452as described in de Dear et al. 8. The total latent heatloss from the skin due to evaporation, Qev, is given byQevi wi psk;si ? pa?AiRcli=gclLR 1=hcvi fcli LR7where, w is the wettedness ratio, psk,sis the saturatedwater vapor partial pressure at the skin temperatureand pais the water vapor partial pressure in theambient air, gclis permeation efficiency of the clothingand LR is the Lewis Relation which is the ratio of theevaporative heat transfer coefficient to the convectiveheat transfer coefficient. McCullough et al. 14 havebeen found an average value of gcl=0.34 for commonindoor clothing.The total skin wettedness (w), includes wettednessdue to regulatory sweating (wsw) and to diffusionthrough to skin (wdif) is given bywswi hfg_ mswiQev;maxi8wdifi 0:06 1 ? wswi9wi wswi wdifi10Maximum evaporation potential, Qev,maxoccurs whenthe skin surface is completely wetted (w=1).In an automobile, a significant portion (1520%) ofthe body surface area is in contact with a seat, backsupport and steering wheel 5. This portion does notlose heat by convection and radiation. The heat lossfrom the skin due to conduction is given byQcdi Tski ? TintRcliAcdi11In the two-node model, heat exchange between thecoreandtheskinoccursbydirectcontactandthrough the skin blood flow. A constant averagethermalconductance,Kcr,sk=5.28 W/(m2K)isas-sumed over the body. The heat flow from core to skinis as follows:Qcr;ski Kcr;sk cp;bl_ mbl?Tcri ? Tski Ai12The specific heat of the blood, cp,blis 4,187 J/(kg K).Respiratory heat loss is approximately 10% of total heatloss 9. The heat loss due to respiration is given byQres _ mrescp;aTex? Ta hfgWex? Wa?Ab13where _ mresis the mass flow rate of air inhaled, Texand Taare the exhaled air and the ambient air temperatures,respectively. Wexand Waare the exhaled air and theambient air humidity ratio, respectively. The heat ofvaporization (hfg) is 2.43106J/kg._ mres 2:58 ? 10?6?M14Tex 32:6 0:066Ta 32Wa15Wex 0:0277 0:000065Ta 0:2Wa16The ratio of the skin mass to total body mass (a) ismodeled as the following function of core to skin bloodflow:a 0:0418 0:7453;600 _ mbl 0:58517The blood flow between the core and the skin per unit ofskin area is expressed as_ mbl6:3 200WSIGcr= 1 0:5CSIGsk?3;60018The rate of sweat production per unit of skin area isestimated by_ msw 4:7 ? 10?5WSIGbexpWSIGsk10:7?19The average temperature of human body can be pre-dicted by the weighted average of the skin and coretemperatures:Tb aTsk 1 ? aTcr20The neutral body temperature is calculated from theneutral skin and core temperatures in the same man-ner.The body is divided into 16 segments which are uni-formly clothed. The total thermal resistance and thetotal evaporative resistance for each segments are asfollows 14:Rti Rairi;0ri;nlXnlj1Rali;jri;0ri;j ? 1 Rfi;jri;0ri;j?21Rev;ti Rev;airi;0ri;nlXnlj1Re;ali;jri;0ri;j ? 1 Re;fi;jri;0ri;j?22It is assumed that heat transfer through air layersbetween clothing layers occurs by conduction and radi-ation. In this case, thermal resistance of an air layer isgiven byRal1hrd k=xa23where xais air layer thickness. The values of hrdand kwere taken as hrd=4.9 W/(m2K) and k=0.024 W/(mK)14. Similar equation can be written for the evaporativeresistance. Evaporative resistance of an air layer is givenby:453Rev;al a 1 ? exp?xab?hi24where a and b are constants. The values of a and b are0.0334 (m2kPa)/W and 15 mm, respectively 14. Theouter surface exposed to the environment is treated alittle differently. The thermal resistance of the outerlayer is then:Ra1hcv hrd25The evaporative resistance of the outer layer can bedetermined from the convective heat transfer coefficientand the Lewis Relation:Rev;a1hcvLR262.2 Prediction of thermal sensationThe above equations describe thermal exchange betweenthe human body and the environment and thermoregu-latory control mechanisms. Combination of the thermalenergy on the body, thermal load, affects the humanthermal comfort in the thermal energy exchange (tran-sition) between the body and its environment. If thethermal load (L) on the body is nearly zero, then neu-trality or thermal comfort is achieved. Combinations ofactivity, clothing and the four environmental variables(air temperature, mean radiant temperature, air velocityand humidity) all affect thermal comfort. The mostwidely used thermal comfort index is the thermal sen-sation (TS) value is given by Eq. 27.TS 0:303exp?0:036MAb? 0:028?L27where Abis the total surface area of the body. The TSscale is given in the Table 4.2.3 Assumptions and initials conditionsNude body surface area is taken as Ab=1.751 m2. Bodymass (m) is 80 kg and initial values of core and skintemperatures are taken as 36.8 and 33.7?C respectively3.Summer clothing insulation, winter clothing insula-tion, clothing area factor for summer clothing, clothingarea factor for winter clothing and metabolic activity aretaken as 0.5 clo, 1.5 clo, fcl= 1.1, fcl= 1.15 and75 W/m2, respectively 5, 6.Table 4 Scale of TS values0 thermal neutrality1 slightly warm?1 slightly cool2 warm?2 cool3 hot?3 cold4 very hot?4 very cold5 painfully hot?5 painfully coldFig. 1 Automobile interior air temperature during heating processFig. 2 Temperatures inside the automobile and human bodycontact surfacesFig. 3 Relative humidity values during cooling process inside theautomobile454Local air velocities on the body is given in the Table 1and mean air temperature (Ta) for heating and coolingprocesses is taken as given in Figs. 1 and 2. Relativehumidity in heating period is taken as 0.35 5 and incooling period it is taken as given in Fig. 3. Meanradiant temperature in heating period is taken as?Trd 0:94Ta? 1:38 and in cooling period is taken as?Trd ?0:007752T2a 1:625778Ta? 6:879288:Surface temperatures of solids in contact with thebody (Tint) in heating period (t is time from start-up inminutes) were 5:SeatTint 41 1 ? exp?t4? 20for t ? 15Tint 20 0:367t ? 15for t 15Clothed area in contact with seat: 0.07 m2Back supportTint ?20 30tfor t ? 1Tint 14:61 ? exp ?t ? 15? 10for 1t10Tint 22:2 0:065t ? 10for t ? 10Clothed area in contact with back support: 0.07 m2Steering wheelTint 40 1 ? exp?t6? 20Clothed area in contact with steering wheel: 0.01 m2.In cooling period, surface temperatures of solids incontact with the body (Tint) are found as follows as aresult of performed experiments. (where t is in minutes)(Table 5).Tint at2 bt c283 Results and discussionsIn order to investigate the effects of automobile interiorconditions resulted by heating and cooling process, theequations given in Mathematical model section areconducted to computer medium by using the program-ming language Delphi 6. For heating period, requiredexperimental input data such as automobile interior airtemperature and humidity, mean radiant temperature,seat, back support and steering wheel surface tempera-tures are taken from Burch et al. 5. In their experi-mental studies, interior air has been heated from ?20 to20?C as seen from Fig. 1.Table 5 Constants in the Eq. 28For t 2For t2abcabcSeat3.10?15.3065.200.0051?0.387046.0496Back support2.55?13.6562.100.0049?0.330643.7763Steering wheel2.50?16.0067.000.0064?0.461844.6285Fig. 4 Comparison of body heat losses in heating processFig. 6 Average body skin temperature in heating processFig. 5 Comparison of thermal sensation during heating process455Required experimental data for cooling process aremeasured in 1991 Toyota Corona Sedan automobileequipped with a 2,000-cc engine. Automobile is parkedin the sun and it is observed that the increase of tem-perature inside car is 64?C with the ambient temperatureof about 30?C. Later, standard cooling process is startedby running the air conditioning unit. During this processtemperature inside car, relative humidity, seat, backsupport and steering wheel surface temperatures aremeasured. Measured parameters are shown Figs. 2 and3. Since relative humidity decreases from 50 to 11%during the increase of temperature inside car to 64?C,relative humidity in cooling process is started from 11%.Heat losses from body to the environment duringwarm-up process are given in Fig. 4 comparatively.Since the model of Burch et al. 5 and the present modelexhibit some principal differences (e.g., the body isdivided into four segments in Burchs et al. 5 model,whereas it is divided into 16 segments in our model.),some discrepancies appear at the beginning period.Apart from this relatively small time interval, theagreement between the results can be acceptable range.Conduction heat losses to the seat, back support andsteering wheel is rather low in comparison to the totalvalue of convective and radiative heat losses because theareas of body segments in contact with solid surfaces aresmaller than other body surfaces. In the beginning ofwarm-up process, conductive, convective and radiativeheat losses are high since the temperature inside theautomobile and the interior surface temperatures arerather low. Even total of these heat losses are higherthan metabolic heat generation. For this reason, coreand skin temperatures of the body a little decreases. But,the decrease in skin temperature is higher than the de-crease in core temperature. It is observed that rapiddecrease in these heat losses due to increase in the tem-perature inside the automobile. In this process, bodytries to keep respiration and evaporation heat losses inminimum to balance heat losses.Comparative variation of TS values in warm-upperiod is given in Fig. 5. By inspection of Fig. 5, there isa good agreement with the study of Burch et al. 5.These calculations are performed by considering thesame conditions described in the experimental andanalytical studies of Burch et al. 4, 5. In their experi-ments, TS values were obtained by using jury data, andthe mean TS and standard deviation (r) of the jury datawere calculated versus time. The present study calcula-tions are fall within the range of TS1r, and the valueof r is given as 0.62. In the beginning, time heat lossesfrom the body to the environment is very high due tolow temperature inside the car. For this reason, TSindices that considers thermal load on the body has beenstarted from very low values. And then, TS hasimprovedwithincreasinginsidetemperatureandinterior surface temperatures.One of the parameters that indicate the effects ofenvironmental conditions on human comfort during thewarm-up period of automobile cabin is mean body skintemperature and its variation with time is shown inFig. 6. In early minutes, average skin temperatureinstantly decreases due to very low temperatures of bothinside the car and interior surfaces. Since temperatureinside car increases with time, mean skin temperatureincreases after its values drops a minimum value ofFig. 7 Temperature of body parts that contact with solid surfacesin heating processFig. 8 Heat flow between body and environment in cooling processFig. 9 Variation of thermal sensation during cooling process45632?C. Although average skin temperature gives an ideaabout the human comfort condition, it must be paidattention local discomforts on human body. The tem-peratures of back, thigh and hand of the body thatcontact with solid surfaces are given in Fig. 7. Thetemperatures of back and thigh are not much moreaffected from inside temperatures, and so they dontvaryimportantly.Butthehand-skintemperaturedecreases to a value of 17.5?C that can be evaluated as arather low temperature. In literature, it is mentionedthat hand-skin temperature of 20?C causes a report ofuncomfortably cold; and 15?C, extremely cold 3.Heat transfer from the body in cooling process isgiven in Fig. 8. Since inside temperature and interiorsurface temperatures are high at the beginning, sensibleheat flow (conduction, convection and radiation) occursfrom environment to the body. This situation contrib-utes to increase in core and skin temperatures. To con-tinue vital functions and in addition to ensure comfortconditions, the heat from environment to body andmetabolic heat generation of body must be emitted toenvironment. For this reason, body increases the sweatgeneration, and then a large portion of the body iscovered by sweat. In this way, evaporative heat loss in-creases as shown in Fig. 8. Whereas respiration loss isnot affected by ambient conditions and it stays about10 W.The variation of TS for cooling period is givencomparativelywithChakrounandAl-Faheds7study in Fig. 9. In Chakroun and Al-Faheds 7paper, detailed ambient conditions were not given, soour model could not be applied directly to theirmeasurement conditions. Therefore, this figure presentsonly a qualitative comparison. In their study, it isensured the temperature inside car reaches up toapproximately 65?C by parking in the sun. Then,cooling process is investigated by running the A/Cunit. But experiments are performed in relatively hotclimateandambienttemperatureisabout45?C.However it is about 30?C in our experiments. And theradiation from the sun is also stronger than our cases.For this reason, temperature profile inside the car isdifferent and depending on this TS values are alsodifferent. In early minutes, due to high inside tem-peratures, heat is transferred from environment to thebody by conduction, convection and radiation. Forthis reason, since the body has a significant thermalload, TS starts from very high values. Then, thermalload decreases with decreasing the temperature insidecar and the surface temperatures and comfort condi-tion gets better.The variation of mean body, feet, and hand-skintemperatures during the cooling process is given inFig. 10. In early times, since the temperature insidethe car is very high (?64?C), the temperatures of theall body segments rise. But, the temperature rise of thehand that directly contacts with air is higher thanother segments. Since inside the car cools with timethis rise decreases. Hands are most affected fromambient conditions, so obvious decrease in tempera-ture occurs on hand. Similar situation is valid forhead. Since shoes are important insulation element,feet are not affected from the interior temperaturevariations. For this reason, the highest temperature atthe end of cooling process occurs at feet. Mean skintemperature of the body varies between hand and feettemperatures.One of the important parameters that affect thecomfort sensation is skin wettedness and its variationwith time is given in Fig. 11. At the early stage ofcooling process, since temperature inside car is high,sweat generation rate is increased to increase heat lossfrom body. So skin wettedness on the body increases.The most rapid increase occurs at feet due to shoes.Since there is no clothing that prevents evaporation ofsweats on the head, and hands that do not contact withsteering wheel, the skin wettedness is the lowest on theseparts of the body. Whereas mean body skin wettednessrises to the maximum value of 0.6 between the wetted-ness of head and feet.Fig. 10 Mean body, hand and feet skin temperatures duringcooling processFig. 11 Mean body, hands and feet skin wettedness in coolingprocess4574 ConclusionsIn this study, the effects of interior environmentalconditions on the human physiology and comfort inheating and cooling processes are int
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