Gas-phase transport and entropy generation during transient combustion of a single biomass particle in varying oxygen and nitrogen atmospheres

Wang, L., Karimi, N. and Paul, M. C. (2018) Gas-phase transport and entropy generation during transient combustion of a single biomass particle in varying oxygen and nitrogen atmospheres. International Journal of Hydrogen Energy, 43(17), pp. 8506-8523. (doi:10.1016/j.ijhydene.2018.03.074)

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Abstract

Transient combustion of a single biomass particle in preheated oxygen and nitrogen atmospheres with varying concentration of oxygen is investigated numerically. The simulations are rigorously validated against the existing experimental data. The unsteady temperature and species concentration fields are calculated in the course of transient burning process and the subsequent diffusion of the combustion products into the surrounding gases. These numerical results are further post processed to reveal the temporal rates of unsteady entropy generation by chemical and transport mechanisms in the gaseous phase of the reactive system. The spatio-temporal evolutions of the temperature, major chemical species including CO, CO2, O2, H2 and H2O, and also the local entropy generations are presented. It is shown that the homogenous combustion of the products of devolatilisation process dominates the temperature and chemical species fields at low concentrations of oxygen. Yet, by oxygen enriching of the atmosphere the post-ignition heterogeneous reactions become increasingly more influential. Analysis of the total entropy generation shows that the chemical entropy is the most significant source of irreversibility and is generated chiefly by the ignition of volatiles. However, thermal entropy continues to be produced well after termination of the particle life time through diffusion of the hot gases. It also indicates that increasing the molar concentration of oxygen above 21% results in considerable increase in the chemical and thermal entropy generation. Nonetheless, further oxygen enrichment has only modest effects upon the thermodynamic irreversibilities of the system.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Paul, Dr Manosh and Wang, Miss Linwei and Karimi, Dr Nader
Authors: Wang, L., Karimi, N., and Paul, M. C.
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
Journal Name:International Journal of Hydrogen Energy
Publisher:Elsevier
ISSN:0360-3199
ISSN (Online):1879-3487
Published Online:04 April 2018
Copyright Holders:Copyright © 2018 Hydrogen Energy Publications LLC.
First Published:First published in International Journal of Hydrogen Energy 43(17):8506-8523
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
709761Thermally Driven Heat Pump Based on an Integrated Thermodynamic Cycle for Low Carbon Domestic Heating (Therma-Pump)Zhibin YuEngineering and Physical Sciences Research Council (EPSRC)EP/N020472/1ENG - ENGINEERING SYSTEMS POWER & ENERGY