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[综述] Gas diffusion in coal particles: A review of mathematical models and their applications

Abstract

As key flow properties for coalbed methane production, greenhouse gas reduction through CO2 storage in coal and gas drainage to improve mining safety, knowledge of gas diffusion in coal has attracted significant interest. In the past decades, numerous efforts have been made to study the nature of gas diffusion in coal both experimentally and theoretically, and many models, including analytical and empirical models, have been proposed. However, because the assumptions, simplifications and applications of these models differ greatly, it is essential to critically review, compare and classify them for better use in practice. Therefore, this article reviews the state of the art on the gas diffusion in coal particles from the aspects of definition, mathematical models, experimental methods, and applications in environment, energy and mining safety areas. Moreover, this review article also dedicates to investigate the inter-relationships between different models, classify them into different categories and identify their limitations when they are applied in different areas. Based on these analyses, the potential research areas related to gas diffusion in coal are proposed.

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朗格缪尔模型综述 Langmuir’s Theory of Adsorption: A Centennial Rev

Langmuir方程是常用的吸附等温线方程之一,是由物理化学家朗格缪尔(Langmuir Itying)于1916年根据分子运动理论和一些假定提出的。现广泛应用于吸附学方面。

朗格缪尔的研究认为固体表面的原子或分子存在向外的剩余价力,它可以捕捉气体分子。这种剩余价力的作用范围与分子直径相当,因此吸附剂表面只能发生单分子层吸附。

该方程较好地描述了低、中压力范围的吸附等温线。当气体中吸附质分压较高,接近饱和蒸汽压时,该方程产生偏差。这是由于这时的吸附质可以在微细的毛细管中冷凝,单分子层吸附的假设不成立的缘故。

想深入了解朗格缪尔模型的前世今生,请阅读:

Swenson, H., & Stadie, N. P. (2019). Langmuir’s Theory of Adsorption: a Centennial Review. Langmuir. 2019, 35 (16), pp 5409–5426.

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1. Langmuir’s Theory of Adsorption: A Centennial Review

2. Langmuir’s Theory of Adsorption A Centennial Review_SI