ASTM C1774-13
低温绝热系统热力性能测试的标准指南

Standard Guide for Thermal Performance Testing of Cryogenic Insulation Systems

被代替

ASTM C1774-13 发布历史

ASTM C1774-13由美国材料与试验协会 US-ASTM 发布于 2013。

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ASTM C1774-13 发布之时，引用了标准

• ASTM C1029 喷施的刚性蜂窝状聚氨基甲酸乙酯绝热材料标准规范
• ASTM C1045 在稳态条件下计算热传递性能的标准规程
• ASTM C1058 评价和报告绝热材料热性能用温度的选择的标准实施规程
• ASTM C1482 聚酰亚胺柔性蜂窝绝热和吸声材料的标准规范
• ASTM C1484 真空绝缘板标准规范
• ASTM C1594 聚酰亚胺硬质蜂窝绝热材料标准规范
• ASTM C1667 使用热流计测量真空隔热板中心热传导系数的标准试验方法*， 2023-07-06 更新
• ASTM C167 毛毡或棉绒型绝热材料厚度和密度的标准试验方法
• ASTM C168 与隔热有关的标准术语
• ASTM C1728 柔性气凝胶绝缘材料标准规范
• ASTM C177 用护热板法测定稳态热通量和传导性的标准试验方法
• ASTM C335 卧式隔热管稳定传热特性的标准试验方法
• ASTM C518 用热流计法测定稳态热通量和热传递特性的标准试验方法
• ASTM C520 粒状疏松的填充隔热材料密度的标准试验方法
• ASTM C534 薄板和Tubular Form预制弹性弹性细胞隔热材料的标准规范
• ASTM C549 珍珠岩松散填充绝缘规范
• ASTM C552 多孔玻璃隔热材料的标准规范
• ASTM C578 硬质多孔聚苯乙烯绝热材料的标准规范
• ASTM C591 未经加工的预制刚性多孔聚异氰尿酸盐隔热材料标准规范
• ASTM C680 用计算机程序控制测定绝热管及设备系统的表面温度和吸热或热损失的规程
• ASTM C740 低温作业中真空反射隔热标准实施规程
• ASTM C870 热绝缘材料的调整的标准实施规程
• ASTM E230 标准化热电偶用温度电动势(EMF)图表的标准规范
• ASTM E408 用监测仪技术测定表面正常总辐射的标准试验方法
• ASTM E691 为测定试验方法精密度开展的实验室间的研究
• ISO 21014 低温容器.低温绝缘性能.修改件1

* 在 ASTM C1774-13 发布之后有更新，请注意新发布标准的变化。

ASTM C1774-13的历代版本如下：

• 2019年 ASTM C1774-13(2019) 低温绝缘系统热性能测试标准指南
• 2013年 ASTM C1774-13 低温绝热系统热力性能测试的标准指南

5.1 A key aspect in understanding the thermal performance of cryogenic insulation systems is to perform tests under representative and reproducible conditions, simulating the way that the materials are actually put together and used in service. Therefore, a large temperature differential across the insulation and a residual gas environment at some specific pressure are usually required. Added to these requirements are the complexities of thickness measurement at test condition after thermal contraction, verification of surface contact and/or mechanical loading after cooldown, and measurement of high vacuum levels within the material. Accounting for the surface contact resistance can be a particular challenge, especially for rigid materials (32). The imposition of a large differential temperature in generally low density, high surface area materials means that the composition and states of the interstitial species can have drastic changes through the thickness of the system. Even for a single component system such as a sheet of predominately closed-cell foam, the composition of the system will often include air, moisture, and blowing agents at different concentrations and physical states and morphologies throughout the material. The system, as tested under a given set of WBT, CBT, and CVP conditions, includes all of these components (not only the foam material). The CVP can be imposed by design or can vary in response to the change in boundary temperatures as well as the surface effects of the insulation materials. In order for free molecular gas conduction to occur, the mean free path of the gas molecules must be larger than the spacing between the two heat transfer surfaces. The ratio of the mean free path to the distance between surfaces is the Knudsen number (see C740 for further discussion). A Knudsen number greater than 1.0 is termed the molecular flow condition while a Knudsen less than 0.01 is considered a continuum or viscous flow condition. Testing of cryogenic-vacuum insulation systems can cover a number of different intermediate or mixed mode heat transfer conditions.

5.2 Levels of thermal performance can be very high: heat flux values well below 0.5 W/m2 are measured. This level of performance could, for example, correspond to a ke below 0.05 mW/m-K (R-value = 2900 or higher) for the boundary temperatures of 300 K and 77 K and a thickness of 25 mm. At these very low rates of heat transmission, on the order of tens of milliwatts for an average size test apparatus, all details in approach, design, installation, and execution must be carefully considered to obtain a meaningful result. For example, lead wires for temperature sensors can be smaller diameter, longer length, and carefully installed for the lowest possible heat conduction to the cold mass. In the case of boiloff testing, the atmospheric pressure effects, the starting condition of the cryogen, and any vibration forces from surrounding facilities should also be considered. If an absolute test apparatus is to be devised, then the parasitic heat leaks shall be essentially eliminated by the integrated design of the apparatus and test methodology. The higher the level of performance (and usually the higher level of vacuum), the lower the total heat load and thus the parasitic portion shall be near zero. For a comparative apparatus, the parasitic heat leaks must be reduced to a level that is an acceptable fraction of the total heat load to be measured. And most importantly, for the comparat........

标准号

ASTM C1774-13

发布

2013年

发布单位

美国材料与试验协会

替代标准

ASTM C1774-13(2019)

当前最新

ASTM C1774-13(2019)

 

 

引用标准

ASTM C1029 ASTM C1045 ASTM C1058 ASTM C1482 ASTM C1484 ASTM C1594 ASTM C1667 ASTM C167 ASTM C168 ASTM C1728 ASTM C177 ASTM C335 ASTM C518 ASTM C520 ASTM C534 ASTM C549 ASTM C552 ASTM C578 ASTM C591 ASTM C680 ASTM C740 ASTM C870 ASTM E230 ASTM E408 ASTM E691 ISO 21014

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