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相关概念视频

Thermal Insulation in Masonry Walls01:22

Thermal Insulation in Masonry Walls

109
In hot, dry climates, the thermal mass of masonry walls can be beneficial, absorbing heat during the day and releasing it at night, thereby stabilizing indoor temperatures. However, in most other climates, additional insulation is necessary to enhance thermal resistance.
External insulation can be applied using an Exterior Insulation and Finish System (EIFS), which involves affixing panels of plastic foam to the wall and covering them with a polymeric stucco reinforced with glass fiber mesh....
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Frost Resistant Concrete01:29

Frost Resistant Concrete

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Concrete's susceptibility to frost damage during freeze-thaw cycles demands strategic measures to enhance its frost resistance. Employing techniques like air entrainment, adjusting the water-cement ratio, proper curing, and selecting appropriate aggregates are essential.
Introducing microscopic air bubbles into the concrete mix through air entrainment creates small voids that accommodate ice expansion, thereby reducing internal pressures and preventing cracking. The optimal amount of...
75
Frost Action on Concrete01:27

Frost Action on Concrete

94
Concrete structures in cold climates, such as those along roadsides, can retain moisture. This moisture makes them susceptible to frost-related damage when temperatures fall below freezing. Adding moisture worsens the damage during temperature fluctuations, leading to repeated freezing and thawing. De-icing salts, spread over these structures to melt ice, add to the freeze-thaw cycle, and draw even more moisture into the concrete.
This freeze-thaw cycle primarily causes surface scaling, where...
94
Cold Weather Concreting01:27

Cold Weather Concreting

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When freshly poured concrete is exposed to freezing temperatures before it has set, the water within the concrete can freeze. This expansion disrupts the setting process, delays chemical reactions necessary for hardening, and increases the volume of pores within the hardened concrete, which weakens its overall structure. If the concrete manages to reach an appreciable strength before it freezes, the damage can be somewhat mitigated.
To counteract the negative impacts of cold weather, ensuring...
61

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Achieving Moderate Pressures in Sealed Vessels Using Dry Ice As a Solid CO2 Source
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低温绝缘 - - 向环保型聚氨泡发展

Laima Vevere1, Vladimir Yakushin1, Beatrise Sture-Skela1

  • 1Latvian State Institute of Wood Chemistry, 27 Dzerbenes Str., LV-1006 Riga, Latvia.

Polymers
|September 14, 2024
PubMed
概括

先进的冷绝缘材料,包括聚氨泡,正在与可持续的吹风剂和生物基聚合物演变. 这些创新旨在提高低温应用的热性能并减少对环境的影响.

科学领域:

  • 材料科学 材料科学 材料科学
  • 热力学是一种热力学.
  • 化学工程是化学工程的重要组成部分.

背景情况:

  • 低温技术涉及非常低的温度 (低于120K),对于液化天然气 (LNG) 运载器和太空发射器等应用至关重要.
  • 有效的绝缘在冷技术中至关重要,以尽量减少沸和防止结.
  • 刚性封闭细胞泡,特别是聚氨 (PU) 泡,为冷绝缘提供热和机械性能的平衡.

研究的目的:

  • 审查冷绝缘材料的进展情况.
  • 突出可持续组件的整合,如环保喷雾剂和生物基聚合物.
  • 评估这些创新对热性能和环境可持续性的影响.

主要方法:

  • 对当前冷绝缘材料和技术的文献综述.
  • 分析第四代物理吹气剂 (例如HFO) 的性能.
  • 从可再生资源中获得的生物基聚醇和在PU泡中回收PET的评估.

主要成果:

  • 聚氨泡被广泛使用,特定类型适用于内部 (高强度) 和外部 (低密度) 低温绝缘.
  • 像HFO-1233zd (E) 和HFO-1336mzz (Z) 这样的新型吹气剂具有较低的全球变暖潜力和增强的导热性.
  • 来自天然油和回收PET的生物基聚合物显示出创造可持续的刚性PU泡具有理想的冷性质的前景.
关键词:
生物基聚类是生物基聚类.节能节能节能节能节能节能节能第四代吹气剂是第四代吹气剂.液体气体的储存储存是液体气体.太空技术 太空技术

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结论:

  • 低温绝缘的发展正在向可持续性转变,结合了环保的吹剂和生物基聚.
  • 这些先进材料在冷储存和运输中提供了更好的热性能和更少的环境影响.
  • 目前正在进行的研究重点是优化这些材料,以获得卓越的机械性能和生态效益.