应用二维热阻图研究空心节能墙体砌块传热特性

对空心节能墙体砌块,应用二维热阻图改进传统的一维传热估算法求解热阻图中各节点能量方程得出了墙体砌块传热特性。分析墙体黑度ε对传热的影响可知:随ε增大,孔洞中辐射换热作用增强,对流换热减弱,一般材料的墙体砌块辐射换热量和对流换热量与砌块总换热量之比均为35%左右。单排孔砌块的热阻不一定高于无孔砌块的热阻,但两排孔砌块可比无孔砌块节能29%。计算与测试结果的比较表明计算是可靠的。     

空心墙体建筑的节能及经济性分析

对空心墙体的静态热阻计算考虑了对流和辐射对热阻的影响,并用非稳态传热理论和计算机模拟分析的方法,利用传递函数法求解新型节能空心墙体的传热过程,计算某建筑物的围护结构(传统实心墙体和新型空心墙体)的全年逐时能耗和总能耗,并根据计算结果进行节能分析和经济性分析,得出:建筑物采用节能空心墙体与传统实心墙体相比,夏季节能27 19%,冬季节能23 92%,其投资可在10a内回收。     

废渣小型空心砌块墙体排列和砌筑方法

废渣小型空心砌块墙体排列和砌筑方法徐州市第三建筑工程公司１９９１年～１９９４年，我们承担了在工业与民用建筑中采用砼（废渣）小型空心砖块的施工任务。施工前我们绘制了墙体的砌块排列图，然后根据有关建筑设计与施工规程进行施工，收到较好的效果。ｌ砌块墙体的排...     

关于促进粉煤灰小型空心砌块推广应用的建议

对国标《轻集料混凝土小型空心砌块》(GB／T15229—2002)和国家建筑标准图集《框架结构填充小型空心砌块墙体建筑构造》以及其对粉煤灰小型空心砌块推广应用的影响．作了简要介绍。对促进粉煤灰小型空心砌块推广应用，提出建议。     

浅谈混凝土小型空心砌块墙体裂缝的控制

混凝土小型空心砌块具有节土、节能等优点.但其却存在着建筑裂缝问题,以致制约着它的发展.文章分析了混凝土小型空心砌块墙体产生裂缝的原因,阐述了其墙体裂缝的防治措施.     

粉煤灰小型空心砌块推广应用中的几个问题

简要说明国标《轻集料混凝土小型空心砌块》(GB/T1 5 2 2 9— 2 0 0 2 )和国家建筑标准图集《框架结构填充小型空心砌块墙体建筑构造》对粉煤灰小型空心砌块推广应用的影响 ,进而提出粉煤灰小型空心砌块推广应用中应解决的几个问题。     

轻集料混凝土空心砌块

在新型墙体材料中 ,轻集料混凝土空心砌块占有很大比例。本文介绍轻集料混凝土空心砌块的技术性能、生产工艺及应用实例 ,指出应用高强陶粒制备的高细轻集料混凝土空心砌块是我国今后发展的重要趋势     

混凝土空心砌块墙体裂缝控制措施研究

在全面推进节能、降耗政策的情况下,新型墙体材料的应用范围正在不断扩大,给混凝土施工技术提出了更高要求,必须加强施工过程的管理,才能进一步提高施工质量。本文就混凝土空心砌块墙体裂缝产生的原因进行分析,对混凝土空心砌块墙体裂缝的控制措施进行探讨,以更好的促进我国建筑行业可持续发展。     

"粉煤灰小型空心砌块"纳入"新型墙体材料目录"值得商榷

就行业标准《粉煤灰小型空心砌块》进行了讨论;并就其粉煤灰用量,以及中国建筑材料科学研究院水泥所进行的粉煤灰小型空心砌块水化机理试验研究生成的水化产物进行了介绍,依据相关国家标准说明“粉煤灰小型空心砌块与”免烧砖“同属耐久性能差的非蒸压粉煤灰硅酸盐制品,不能满足建筑工程质量和安全的需要,将给建筑工程留下隐患。因此,将“粉煤灰小型空心砌块”纳入“新型墙体材料目录”值得商榷。     

复合保温砌块墙体材料制备及性能研究

作为一种集承重与保温于一体的墙体材料,复合保温砌块在建筑工程中的应用量逐渐增加,为了满足建筑节能要求,我国当前的墙体保温材料多以有机高分子材料为主,但其日益凸显的防火与环保劣势不断缩小着自身的市场份额。以优化复合保温砌块性能为目的,将无机保温材料泡沫混凝土填充至混凝土空心砌块中,进行高性能复合保温砌块的制备与性能研究,以提供理论基础于建筑工程中墙体保温材料的设计,提高工程质量。     

建筑外表面对流传质系数的测量方法

建筑外表面对流传质系数是围护结构热湿耦合计算和建筑能耗模拟中的重要参数。为直接准确得到该参数,提出了建筑物壁面对流传质系数的测量方法,该方法通过测量萘试件的质量通量和表面温度,即可计算得到壁面传质系数。为验证该方法的准确性及可靠性,在风洞内设置6组不同风速工况,分别采用了萘升华法与传统热平衡法进行对比。结果表明：随风速的增加,萘试件表面温度随之降低,而对流传质系数逐渐增加。两种方法测试结果接近,二者所得对流传质系数相差在10%以内,不同风速条件下平均偏差小于5%,认为该测量方法可行。该研究可为室外真实条件下建筑外表面对流传质系数提供测试方法指导,对热湿耦合计算和墙体蒸发换热的研究也具有重要意义。     

Method to determine the equivalent thermal diffusion coefficient of the intumescent coating for cables

The thermal diffusion coefficient of the intumescent insulating layer, which forms when a fire-retardant coating is subjected to heat in a fire, is a key factor used in assessing the fire protection performance of the coating. However, because there are many factors influencing this coefficient, it is usually difficult to measure its value directly from tests. Based on the insulation failure experiment of a cable exposed to heat, the relationship between failure time, equivalent thermal diffusion coefficient, and thickness of expansion layer has been determined by means of numerical calculation from a heat transfer model built in this paper; a computing formula has been thus established. According to the formula, the equivalent thermal diffusion coefficient of the expansion layer can be determined after the diffusion coefficient and the thickness of the expansion layer are obtained from the insulation failure experiment of a cable.     

网纹内管双套管双管板安全型换热器的传热性能

以网纹内管型双套管双管板安全型换热器为研究对象,采用内外管接触面积当量法,将网纹内管与外管内壁的接触面积当量成对应接触面积的直槽管;借助计算流体力学（CFD）软件采用数值模拟的方法对内管为当量的直槽管换热器传热性能进行了研究,换热器管壳两侧的介质均为水,分别将空气和水两种介质填充至隔绝腔内,模拟不同入口流量条件下传热特性;引入接触修正系数,在传统传热系数经验公式的基础上,结合网纹管模型特点,获得网纹内管安全型换热器传热系数计算公式,并对不同工况下换热器的传热系数进行理论计算;建立网纹内管安全型换热器传热特性评价实验台。结果表明：内外管接触面积当量法在处理网纹内管安全型换热器传热特性时具有可行性,基于接触修正系数的传热系数工程经验公式计算结果可靠;数值模拟结果、理论计算结果及实验结果具有较好的吻合趋势;隔绝腔介质分别为水及空气时,网纹内管的传热效率比内管为光管分别提高约24%和40%。     

异形整体式热管散热器传热实验与分析

针对电子电气设备散热和均温的需求,提出了一种新型结构形式的异形整体热管散热器：平板热管形式的蒸发段与具有高肋化比翅片的冷凝铜管集成。对该热管进行了传热实验与分析,研究热管在不同工况下温度数值及分布,探究影响热管性能的因素和规律,验证其传热能力。结果表明：在各种工况下热管温差始终在1.75℃之内,均温性能良好。加热功率和对流散热状况对热管启动性能、总体热阻、当量热导率、传热系数都有影响。随着加热功率和对流速度增加,热管启动时间和热阻均降低,当量热导率和传热系数则逐渐上升。热阻最低为0.189℃·W^-1,最佳当量热导率为20964 W·m^-1·K^-1。相比于同等尺寸的传统热管,热阻降低了37%,传热效率提升15%。     

石膏基相变储能构件的数值模拟分析

以石蜡为相变储能材料,石膏为基础材料,制备不同配比的石膏基-石蜡相变储能构件并利用现有热工测试方法进行了热工性能测试。将测试数据代入经验证过的相变模型模拟了北京地区被动式建筑中相变构件的应用效果,并对结果进行了优化处理。结果表明：随着石蜡含量的增大,相变构件的热导率随之减小;制备的四种配比中PCM质量分数为33%的相变构件在北京地区被动式建筑中应用效果最好,在过渡季中较传统建筑可节能10%;增大构件的热导率与提高墙体表面对流传热系数均可提高室内舒适度与节能效果,且对流传热系数的影响程度更大。     

Use of effective conductivities and unit cell-based supraelements in the numerical simulation of solid oxide fuel cell stacks

The numerical simulation of current and temperature distribution in monolithic solid oxide fuel cell (SOFC) stacks requires fast computers because of the large number of mesh points required in casting a complex solid geometry into a finite difference form and the necessity to solve coupled, nonlinear differential equations. By analogy with the modelling of radiative heat transfer in packed bed reactors, a significant degree of simplification is achieved by defining effective electric and thermal conductivities for the repeating unit cell elements, identified as the basic building blocks of the SOFC stack. The effective conductivities are approximated by closed form formulae derived from the principles of electrostatics and heat conduction. The effect of radiation across the gas channels is incorporated into the expressions for the effective thermal conductivity. Using this approach, the unit cell geometry, local mass transfer processes and reaction kinetics are expressed in terms of a supraelement model in a finite difference grid for the numerical calculation of temperature and potential distributions in a stack by an iterative process. The simplifications thus provided render simulations of three-dimensional SOFC stacks tractable for desktop processors. By using the foregoing approach to numerical simulation, a parametric study of a cross-flow type SOFC is presented, and some of the results are compared with the available experimental data     

Evaluation of thermal and energy consumption behavior of novel foamed copper slag based geopolymer masonry blocks

The building sector is focused on adopting passive design strategies to reduce the energy needs of the building envelope. Currently there has been lack of research related to the understanding of thermal and energy efficiency performance of foamed geopolymer based material. In this regard, this research provides a solution of thermally efficient wall material developed from copper industry by-product (copper slag). All the performance criteria (i.e. physical, mechanical and thermal) of the developed foamed copper slag geopolymer (FCSG) blocks as a building block was found to be in compliance with the performance of standard commercial product (i.e., autoclave aerated block). Further, the numerical analysis of the developed FCSG material is performed and the conjugate heat transfer through three different solid-wall zones to the fluid domain is perceived. The incompressible conjugate heat transfer solver is developed in the open-source computational fluid dynamics (CFD) tool OpenFOAM to perform the present numerical analysis. It is noted that the temperature in the fluid zone for the FCSG layer attained less than 300 (K) however, for the red clay bricks it reaches 302 (K). Hence, the thermal efficiency of the FCSG incorporated insulation layer reduces the heat transmission from outdoor to indoor, consequently improving the comfortable environment of occupants. Further, the developed blocks were subjected to simulation study using eQuest tool to understand the influence of its thermal characteristics on energy demands. The study found that the yearly energy savings was found to be 7.5% in comparison to commercially available clay bricks. Also, the cost savings can reach up to 8.94% during the peak summer month and 7.4% annually. Thus, the developed blocks emphasize waste utilization, providing better indoor thermal for occupant and energy efficiency benefits for end-users. Thus, achieving overall sustainability as a building envelope component.     

架空热油管道保温层厚度计算

建立了管道保温计算的数学模型,通过具体实例,用计算机编程得出大量数据,通过origin8.0软件绘出保温层厚度分别与保温效率、管道总传热系数、保温层表面温度和沿程温降的关系图,不仅直观地体现了保温层厚度对管道传热的影响以及变化趋势,还可以从图中查出任意厚度下的保温情况,为求解热油管道保温层厚度提供一种新方法。     

超疏水表面有滑移时的层流换热分析

在考虑速度滑移的前提下,对于圆管形微通道内温度边界层充分发展的恒热流量对流传热,推导了速度和温度分布表达式,并进一步得到对流传热系数和Nusselt数计算式。此外,还针对超疏水表面不同结构参数下的滞留空气层,提出了超疏水表面的有效导热模型,推导出超疏水表面不同结构参数下的热阻。最后将传热系数与超疏水表面热阻进行耦合,得出超疏水表面有效传热系数及其与超疏水表面结构参数的关系。计算结果表明:超疏水表面上流体的滑移使得管内温度更加均匀,传热系数或Nusselt数有所增加,恒热流条件下最多可以增加1.8倍;超疏水表面热阻随肋间距和肋高的增加而增大;超疏水表面的表观传热系数随肋间距或孔宽的增加而显著降低,随肋高或孔深的增加,表观传热系数也降低,其幅度与肋间距以及肋高与肋间距之比有关;各种结构参数条件下均存在表面滞留空气层的临界厚度,在此厚度以下表面有效传热系数不低于普通表面无滑移时的数值。因此,需要综合考虑超疏水表面的结构参数,包括肋高、肋间隙等,才能使超疏水表面有利于传热。     

同轴式内部热耦合精馏塔的传热性能

提出了一种以实验物系的物性数据为基础的计算同轴式内部热耦合精馏塔（HIDiC）总传热系数的方法。本文以乙醇-水为实验物系,以自行搭建的中试规模同轴式HIDiC为研究对象,通过在不同压缩比下（1.4~2.6,步长为0.1）的连续操作实验研究,得到塔内的温度分布,通过计算两塔段的相变给热系数来计算该塔的总传热系数和精馏塔段与提馏塔段间的换热量。在同轴式HIDiC中乙醇-水实验物系总传热系数的计算值在300~800W/(m²·K),并且随着压缩比的增大而逐渐降低。在操作条件和产品纯度与实验值保持一致的情况下,将精馏塔段与提馏塔段间换热量的计算值带入软件中模拟,得到的全塔温度分布与实验中的温度分布在误差范围内吻合良好,证明本文计算同轴式HIDiC总传热系数的方法切实有效。