Fundamental Processes of Solid and Liquid Biofuels Combustion

固体和液体生物燃料燃烧的基本过程 木材和其他生物质燃料，无论是固体还是液体，都是具有吸引力的“碳中性”能源。它们的有效利用需要彻底了解它们的燃烧过程，这项提案涉及为生物燃料燃烧的某些方面开发计算工具并进行实验验证。所有项目的共同之处是需要处理具有一定复杂性的固体和液体混合物。 固体生物质燃料通常在填充床中燃烧或气化：在炉排上放置相当大的燃料颗粒的非流态化床。这是一个复杂的过程，目前还不像许多燃烧过程那样被很好地理解。实际燃料通常是具有多种不同颗粒大小和形状的混合物，并且通常还含有几种具有不同燃烧特性的组分(例如木材废料)。拟议的工作将开发在填充床燃烧的数值模型中处理此类混合物的方法，并将在一系列燃料上进行实验以验证该模型。木屑等燃料颗粒也会重叠在床上，大大减少了可供燃烧的表面积。将开发通过床上的压力损失测试来测量这种影响的方法。还将研究纤维取向(颗粒)对燃烧和热解的影响。 与常规石油燃料一样，大多数液体生物燃料是含有大量组分的混合物，可以有效地将其建模为连续混合物，将其表示为一个或多个概率密度函数，而不是离散物种。这项提议将进一步发展对液体生物燃料的蒸发和燃烧进行模拟的连续热力学技术。两个特别令人感兴趣的领域是，需要用方法来描述复杂混合物的化学反应动力学，以便对点火和燃烧进行建模，以及对许多生物燃料中存在的极性化合物(如醇)的非理想相平衡进行处理。

Fundamental Processes of Solid and Liquid Biofuels Combustion Wood and other biomass fuels, both solid and liquid, are attractive as “carbon-neutral” energy resources. Their efficient utilisation requires a thorough understanding of their processes of combustion, and this proposal addresses the development of computational tools for some aspects of biofuels combustion and their experimental verification. Common to all the projects is the need to deal with mixtures, both solid and liquid, of some complexity. Solid biomass fuels are most often burned or gasified in a packed bed: a non-fluidized bed of fairly large fuel particles on a grate. This is a complex process that as yet is not as well understood as many combustion processes. Practical fuels are usually mixtures with a wide range of different particle sizes and shapes, and often have several components with different combustion characteristics as well (e.g. wood wastes). The work proposed will develop methods for dealing with such mixtures in a numerical model of packed bed combustion, and will conduct experiments on a range of fuels to verify the model. Particles of fuels such as wood chips can also overlap in the bed, reducing the surface area available for combustion significantly. Methods will be developed to measure this effect through pressure loss tests on the bed. The effects of fibre orientation (grain) on combustion and pyrolysis will also be investigated. Most liquid biofuels, like conventional petroleum fuels, are mixtures with large numbers of components, and may be modelled effectively as continuous mixtures, representing them as one or more probability density functions rather than in terms of discrete species. This proposal will further develop continuous thermodynamics techniques for modelling the evaporation and combustion of liquid biofuels. The two areas of particular interest are methods are needed to describe chemical reaction kinetics of complex mixtures in order to model ignition and combustion, and the treatment of non-ideal phase equilibrium for polar compounds such as alcohols found in many biofuels.