PhD Defense |Reaction Kinetics for High-Pressure Hydrogen and Methane Oxy-combustion in the Presence of High Levels of H2O and CO2Export this event to calendar

Wednesday, August 11, 2021 — 9:30 AM EDT

Ashkan Beigzadeh  will defend his PhD thesis reaction kinetics for high-pressure hydrogen and methane oxy-combustion in the presence of high levels of H2O and CO2.  This is a closed Defense.

Abstract

Continued use of fossil fueled heat and power generation not only demands switching from carbon intensive fuels such as coal to the likes of natural gas, it also requires equipping them with carbon capture, utilization and storage (CCUS) technologies. One promising carbon capture technology, is oxy-fuel combustion with cooling and compression CO2 capture. Pressurized variants of oxy-combustion technologies integrate CO2 capture and compression into the combustion process, and hold prospects for improved economics and reduced footprint. To reach their full potential, one of the knowledge gaps lies with the lack of understanding of their combustion chemistry, due to the presence of high concentrations of H2O and/or CO2.  The impact of high H2O concentrations on pressurized oxy-combustion kinetics has not been explored.

This research aims to fill this knowledge gap by generating new experimental data and developing experimentally-validated reaction mechanisms.

To this end, novel shock tube experimental ignition delay time (IDT) test data were generated in collaboration with King Abdullah University of Science and Technology (KAUST) for reactive mixtures involving 4% H2, 0.48-3.44% CH4, at equivalence ratios (φ) of 0.93-1. A hierarchical model development and validation approach is presented for high-pressure combustion kinetics in the presence of high levels of H2O and CO2. Two kinetics models, one for H2/CO and another for CH4 high-pressure combustion were developed with particular focus on pressure- and bath gas-dependent reaction rates.

High-pressure H2 IDT experiments were performed at temperatures of 1084-1242 K, pressures of 37-43.8 bar and φ of 1. IDT data for four bath gases, namely: Ar, 45%H2O/Ar, 30%H2O/15%CO2/Ar, and 45%CO2/Ar are provided.

Low-pressure H2 IDT experiments were conducted at temperatures of 917-1237 K, pressures of 1.6-2.4 bar, at φ of 1 in Ar and 45%CO2/Ar baths. A minimally-tuned H2/CO reaction mechanism, CanMECH 1.0, targeting high-pressure combustion in the presence of large concentrations of H2O and CO2 is developed. CanMECH 1.0 is validated against both the IDT data of this work, and other shock tube IDT datasets from literature. CanMECH 1.0 performance is compared to a well-cited incumbent syngas oxidation kinetics mechanism.  CanMECH 1.0 improved model predictions of this work’s IDT data for H2O- and CO2- laden reactive mixtures, as well as all IDT data at pressures of 17-43.8 bars. Overall CanMECH 1.0 also brought about a 26% improvement relative to the incumbent.

High-pressure CH4 IDT experiments were performed at CH4 concentrations of 0.48-0.5%, temperatures of 1536-1896 K, pressures of 37-53 bar, φ of 0.93-1, in Ar, 45%H2O/Ar, 30%H2O/15%CO2/Ar and 45%CO2/Ar baths. Low-pressure IDT experiments were conducted at temperatures of 1486-1805 K, pressures of 1.8-2.4 bar, CH4 concentrations of 3-3.44%, at φ of 1 in Ar and 45%CO2/Ar baths. An improved CH4 reaction mechanism, CanMECH 2.0, is developed, by embedding CanMECH 1.0 (H2/CO mechanism) into a well-validated recent C1-C4 mechanism. CanMECH 2.0 performance is evaluated and compared with the original C1-C4 mechanism as well as another incumbent model. CanMECH 2.0 is shown to improve the overall performance by 1% and 3% relative to the two incumbent mechanisms, respectively.

Supervisor: Professor Eric Croiset

Location 
Online

200 University Ave West

Waterloo, ON N2L 3G1
Canada

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