Dynamic Model of a Fixed Grate Combustion in Modelica
Author
Veje, Johannes
Term
4. semester
Education
Publication year
2016
Submitted on
2016-06-09
Abstract
This thesis develops and tests a dynamic, Modelica‑based control‑volume model for fixed grate combustion. A complete fuel‑bed segment is assembled by combining custom sub‑models with components from the Modelica Standard Library, and each sub‑model is validated against expected behavior or literature data. The segment is exercised across the five key fuel‑bed processes—heat‑up, moisture evaporation, devolatilization, char conversion, and ash cool‑down. In parallel, a gas‑phase combustion segment is formulated using three alternative approaches—chemical kinetics, chemical equilibrium, and an analytical method—whose results are compared, with the analytical approach further explored over a wide range of air–fuel ratios. Under the specified boundary conditions, both the bed segment and the gas combustion segment exhibit the expected behavior, indicating the suitability of the proposed model as a building block for larger dynamic simulations of grate‑fired systems.
Denne afhandling udvikler og afprøver en dynamisk Modelica-baseret kontrolvolumenmodel til fast ristforbrænding. Arbejdet samler et komplet brændsellejesegment ved at kombinere egenudviklede delmodeller med komponenter fra Modelica Standard Library og validerer hver delmodel mod forventet adfærd eller litteraturdata. Segmentet testes gennem de fem centrale processer i et fast brændselleje: opvarmning, fugtfordampning, devolatilisering, char‑omdannelse og askeafkøling. Parallelt opstilles en gasforbrændingsdel med tre alternative tilgange—kemisk kinetik, kemisk ligevægt og en analytisk metode—som sammenlignes, mens den analytiske tilgang yderligere undersøges over et bredt spektrum af luft‑brændselsforhold. Under de givne randbetingelser udviser både brændsellejesegmentet og gasforbrændingssegmentet den forventede adfærd, hvilket peger på modellens egnethed som byggesten i større dynamiske simuleringer af ristfyrede systemer.
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