1.1 本试验方法包括测量流入或流出平板试样的非稳态热流，以使用热流计装置（HFMA）确定储能（即焓）随温度的变化。 1.2 特别是，本试验方法旨在测量包含相变材料（PCM）的产品的显热和潜热储存能力。 1.2.1 PCM的存储容量通过四个参数定义:固相和液相的比热、相变温度和相变焓 ( 1. ) . 2. 1.3 为了更准确地预测热性能，需要有关PCM产品在动态条件下的性能的信息，以补充在稳态条件下测量的特性（热导率）。 注1: 该测试方法定义了含多晶聚合物的产品或复合材料的动态测试协议。由于这些产品或复合材料的宏观结构，常规差示扫描量热仪（DSC）测量中使用的小样本尺寸如 E793 和 E967 ，不一定代表温度和全热焓之间的关系- 扩展PCM产品。 1.4 本试验方法基于用于试验方法的HFMA技术 C518型 但包括本试验方法中概述的PCM产品比热和焓变化测量的修改。 1.5 本试验方法要求在顶部和底部HFMA板上进行热流测量。因此，本试验方法仅适用于在两块板上各配备至少一个热流传感器且具有计算机数据采集和温度控制系统能力的HFMA。此外，流经传感器的能量量必须在所有时间点均可测量。 因此，在测试过程中，传感器输出不得饱和。 1.6 本试验方法进行了一系列测量，以确定试样在温度范围内的蓄热量。首先，将两块HFMA板保持在相同的恒温下，直到达到稳定状态。稳态是指从两块板进入试样的能量减少到非常小且几乎恒定的值。接下来，以相同的量改变两个板的温度，并保持在新的温度，直到再次达到稳定状态。 将记录从温度变化到再次达到稳定状态期间试样吸收或释放的能量。通过一系列温度阶跃变化，确定在特定温度范围内存储或释放的累积焓。 1.6.1 固相和液相的比热由相变过程前后显热/冷却期间温度相关焓函数的斜率确定。 1.7 必须按照以下步骤校准HFMA，以确定板热流传感器内存储能量的“校正系数”，以及放置在试样和HFMA板之间的任何材料 附件A1 . 这些校正系数是每个步骤开始和结束温度的函数，如中所述 附件A1 . 1.8 本试验方法适用于相变材料和复合材料、含有相变材料的产品和系统，包括那些含有分散在隔热材料中或与之结合的相变材料、含有浓缩或分散相变材料的板或膜等。具体示例包括固体相变材料和产品、含有相变材料的松散混合材料和分散含有相变材料的相变材料。 1.9 本试验方法可用于表征材料特性，其可能代表也可能不代表实际使用条件。 1.10 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.11 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.12 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 用于建筑围护结构以提高能效的材料，包括用于隔热、热控制和热存储的PCM产品，受到瞬态热环境的影响，包括瞬态或循环边界温度条件。该测试方法旨在实现有意义的PCM产品分类，因为仅稳态导热系数不足以表征PCM。 注3: 该测试方法定义了包含PCM的复杂产品或复合材料的动态测试协议。 由于这些产品或复合材料的宏观结构，使用中规定的差示扫描量热仪（DSC）进行常规测量 E793 和 E967 使用非常小的样本，由于样本尺寸的限制，不一定代表全尺寸PCM产品的温度和焓之间的关系。 5.2 PCM产品热性能的动态测量只能由了解传热和误差传播的合格人员进行。必须熟悉仪器和产品的配置。 5.3 该测试方法侧重于测试工程应用中使用的PCM产品，包括在建筑围护结构中，以提高绝缘系统的热性能。 5.3.1 PCM在建筑围护结构中的应用有多种形式，包括:分散在隔热材料中或以其他方式与隔热材料结合；在建筑围护结构中实现的一种单独物体，作为包含与隔热材料一起工作的浓缩PCM的板或膜。当暴露于动态（即波动的边界温度条件）时，这两种形式都提高了结构的性能。 5.3.2 PCM可以以多种形式进行研究:作为原始的“纯” PCM ; 作为一个 混合成的 包含PCM和其他嵌入式材料，以提高热性能；作为一个 产品 包含PCM或复合材料（例如微胶囊或宏胶囊PCM）；或作为 系统 ，包括PCM产品的阵列或组件。 5.4 本试验方法描述了使用热流计装置确定PCM产品关键性能的方法，如下所示。工程师、架构师、建模师和其他人需要这些特性来准确预测- 产品现场性能 ( 2. ) . 5.5 目标通常是在试验过程中会导致PCM产品发生相变（例如熔化或冻结）的温度条件下进行试验。 5.6 本试验方法的目的是测定储热性能，主要性能包括: 5.6.1 PCM有效范围，即相变发生的温度间隔，用于PCM产品或含有PCM的复合材料的熔化和冻结。 5.6.2 在PCM有效范围外定义的完全熔化和完全冷冻产品的比热。 5.6.3 焓作为温度的函数， h（T） . 5.6.4 焓图- 柱状图或表格，表明与测试温度范围内的增量温度变化相关的焓变化。 5.6.5 在含有相变材料的材料和复合材料中，相变材料熔化和冻结过程中与相变相关的焓变化。 5.7 PCM产品通常具有使测试期间的相变测量和分析复杂化的特性。 以下是PCM的一些已知问题: 5.7.1 PCM活动范围不精确- 相变材料通常没有精确的熔化或凝固温度，必须确定从相变开始到结束的整个有效温度范围。 注4: 冻结的开始不一定与融化的结束一致。因此，必须独立定义冷冻和熔融焓曲线，以确定PCM的有效范围。 5.7.2 多重相变- 许多相变材料在接近熔融转变的温度下表现出明显的潜热效应。 5.7.3 过冷- 当试样在实际开始冻结之前冷却到其标称冻结温度以下时发生，从而显示出异常的焓-温度曲线。固-液和固-固相变化通常取决于加热和冷却速率。 5.7.4 滞后- 当样本从一个温度加热到另一个温度，然后返回到原始温度时，在加热阶段任何特定温度下吸收的热量大于（或小于）冷却期间释放的热量时发生。 5.8 测量的性能由产品组成材料的基本热物理性能决定，因此是PCM产品固有的。 然而，所需的热性能增强在很大程度上取决于PCM实际工程应用的特定环境、气候和模式。

1.1 This test method covers the measurement of non-steady-state heat flow into or out of a flat slab specimen to determine the stored energy (that is, enthalpy) change as a function of temperature using a heat flow meter apparatus (HFMA). 1.2 In particular, this test method is intended to measure the sensible and latent heat storage capacity for products incorporating phase-change materials (PCM). 1.2.1 The storage capacity of a PCM is well defined via four parameters: specific heats of both solid and liquid phases, phase change temperature(s) and phase change enthalpy ( 1 ) . 2 1.3 To more accurately predict thermal performance, information about the PCM products’ performance under dynamic conditions is needed to supplement the properties (thermal conductivity) measured under steady-state conditions. Note 1: This test method defines a dynamic test protocol for products or composites containing PCMs. Due to the macroscopic structure of these products or composites, small specimen sizes used in conventional Differential Scanning Calorimeter (DSC) measurements, as specified in E793 and E967 , are not necessarily representative of the relationship between temperature and enthalpy of full-scale PCM products. 1.4 This test method is based upon the HFMA technology used for Test Method C518 but includes modifications for specific heat and enthalpy change measurements for PCM products as outlined in this test method. 1.5 Heat flow measurements are required at both the top and bottom HFMA plates for this test method. Therefore, this test method applies only to HFMAs that are equipped with at least one heat flux transducer on each of the two plates and that have the capability for computerized data acquisition and temperature control systems. Further, the amount of energy flowing through the transducers must be measureable at all points in time. Therefore, the transducer output shall never be saturated during a test. 1.6 This test method makes a series of measurements to determine the thermal energy storage of a test specimen over a temperature range. First, both HFMA plates are held at the same constant temperature until steady state is achieved. Steady state is defined by the reduction in the amount of energy entering the specimen from both plates to a very small and nearly constant value. Next, both plate temperatures are changed by identical amounts and held at the new temperature until steady state is again achieved. The energy absorbed or released by the specimen from the time of the temperature change until steady state is again achieved will be recorded. Using a series of temperature step changes, the cumulative enthalpy stored or released over a certain temperature range is determined. 1.6.1 The specific heats of the solid and liquid phases are determined from the slope of the temperature-dependant enthalpy function during sensible heating/cooling, before and after the phase change process. 1.7 Calibration of the HFMA to determine the ‘correction factors’ for the energy stored within the plate heat flux transducers and any material placed between the test specimen and the HFMA plates must be performed following Annex A1 . These correction factors are functions of the beginning and ending temperatures for each step, as described in Annex A1 . 1.8 This test method applies to PCMs and composites, products and systems incorporating PCMs, including those with PCM dispersed in or combined with a thermal insulation material, boards or membranes containing concentrated or dispersed PCM, etc. Specific examples include solid PCM composites and products, loose blended materials incorporating PCMs, and discretely contained PCM. 1.9 This test method may be used to characterize material properties, which may or may not be representative of actual conditions of use. 1.10 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.11 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.12 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Materials used in building envelopes to enhance energy efficiency, including PCM products used for thermal insulation, thermal control, and thermal storage, are subjected to transient thermal environments, including transient or cyclic boundary temperature conditions. This test method is intended to enable meaningful PCM product classification, as steady-state thermal conductivity alone is not sufficient to characterize PCMs. Note 3: This test method defines a dynamic test protocol for complex products or composites containing PCMs. Due to the macroscopic structure of these products or composites, conventional measurements using a Differential Scanning Calorimeter (DSC) as specified in E793 and E967 , which use very small specimens, are not necessarily representative of the relationship between temperature and enthalpy of full-scale PCM products due to the specimen size limitation. 5.2 Dynamic measurements of the thermal performance of PCM products shall only be performed by qualified personnel with understanding of heat transfer and error propagation. Familiarity with the configuration of both the apparatus and the product is necessary. 5.3 This test method focuses on testing PCM products used in engineering applications, including in building envelopes to enhance the thermal performance of insulation systems. 5.3.1 Applications of PCM in building envelopes take multiple forms, including: dispersed in, or otherwise combined with, a thermal insulation material; a separate object implemented in the building envelope as boards or membranes containing concentrated PCM that operates in conjunction with a thermal insulation material. Both of these forms enhance the performance of the structure when exposed to dynamic, that is, fluctuating, boundary temperature conditions. 5.3.2 PCMs can be studied in a variety of forms: as the original “pure” PCM ; as a composite containing PCM and other embedded materials to enhance thermal performance; as a product containing PCM or composite (such as micro- or macro-encapsulated PCM); or as a system , comprising arrays or assemblies of PCM products. 5.4 This test method describes a method of using a heat flow meter apparatus to determine key properties of PCM products, which are listed below. Engineers, architects, modelers, and others require these properties to accurately predict the in-situ performance of the products ( 2 ) . 5.5 The objective is generally to conduct a test under temperature conditions that will induce a phase transition (for example, melting or freezing) in the PCM product during the course of the test. 5.6 Determination of thermal storage properties is the objective of this test method, and key properties of interest include the following: 5.6.1 PCM Active Range, that is the temperature interval over which the phase transitions occur, for both melting and freezing of the PCM product or composites containing PCMs. 5.6.2 Specific heat of the fully melted and fully frozen product, defined outside the PCM Active Range. 5.6.3 Enthalpy as a function of temperature, h(T) . 5.6.4 Enthalpy plot— a histogram or table that indicates the change in enthalpy associated with incremental temperature changes that span the tested temperature range. 5.6.5 Enthalpy changes associated with phase transitions during the PCM melting and freezing processes in materials and composites containing PCMs. 5.7 PCM products often possess characteristics that complicate measurement and analysis of phase transitions during a test. Following are some of the known issues with PCMs: 5.7.1 Imprecise PCM Active Range— PCMs in general do not have precise melting or freezing temperatures, and the entire active temperature range, from the beginning to the end of phase transitions, must be determined. Note 4: The onset of freezing will not necessarily coincide with the end of melting. Therefore, the freeze and melt enthalpy curves must be independently defined to determine the PCM Active Range. 5.7.2 Multiple Phase Transitions— Many PCMs exhibit a solid-solid transition with significant latent heat effects at temperatures near the melting transition. 5.7.3 Sub-cooling— Occurs when the specimen cools below its nominal freezing temperature before it actually begins to freeze, thus exhibiting an unusual enthalpy-temperature curve. Solid-liquid and solid-solid phase changes are often dependent on heating and cooling rate. 5.7.4 Hysteresis— Occurs when a specimen heated from one temperature to another, and then returned to the original temperature, absorbs more (or less) heat at any particular temperature during the heating stage than it releases during cooling. 5.8 The properties measured are determined by fundamental thermophysical properties of the constituent materials of the product, and are thus inherent to the PCM product. The desired thermal performance enhancement, however, will depend strongly on the particular environment, climate, and mode of the actual engineering application of the PCM.