A detailed description of the first functional new approach to simulate the bed physics in biomass boilers in a Eulerian mathematical framework is presented. In particular, the analysis of the context of the collapse due to gravitational forces, the design of an automated algorithm that is responsible for its simulation under ANSYS‐Fluent, the concrete implementation of this algorithm, and its test with experimental contrasted data are described. The proposed solution can replicate the angle of repose of different fuels in biomass combustion boilers by implementing a series of geometric mechanisms applied to the mesh. The selected approach mainly responds to a computational efficiency requirement; both memory management and execution speed are relevant.
The reduction of bed temperature in fixed-bed biomass combustion is an effective measure to lower pollutant emissions. Air staging and bed cooling solutions are active strategies to decrease the fuel bed temperature. This work presents a CFD study of a biomass fixed-bed combustion plant that is equipped with an internal cooling bed system. Eight different cases are calculated to analyze the effect of the total airflow, air staging ratios and bed cooling system on biomass combustion. The findings are validated against experimental data from the literature. The results show good accordance between the numerical results and the experimental data. The primary airflow rate has the biggest influence on the bed’s maximum temperatures. The internal bed cooling system is able to achieve an average bed temperature reduction of 21%, slowing the biomass thermal conversion processes. Bed cooling techniques can be combined with air staging and primary airflow reduction to reduce bed temperatures in order to reduce pollutant emissions and other undesirable phenomena, such as fouling or slagging.
This article introduces a text mining tool that can automatically extract information using Hyland’s analysis
model as a theoretical framework to analyse the use and characteristics of metadiscourse in large quantities of academic texts. To
verify its validity, we present the results obtained using this tool on various bachelor’s degree theses with a particular focus
on the field of engineering. Our results on a 6.9 million-word corpus extracted from 680 bachelor’s theses available online show
that interactive metadiscourse markers are prevalent in engineering bachelor’s theses as well as in the authors’ metadiscourse
patterns. In addition, we compared our results with previous research on metadiscourse markers. Our study can be used to identify
the usage of various types of metadiscourse markers during the production of texts and for the development of software
applications involving quantitative linguistic methods for the production of academic texts.
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