Model Assisted Design of a Fuel-Flexible Hydrogen/Natural Gas Double Swirl Burner

Guilherme de Fonseca Félix Bhudarally

Key information

Authors:

Guilherme de Fonseca Félix Bhudarally (Guilherme de Fonseca Félix Bhudarally)

Supervisors:

José Manuel Da Silva Chaves Ribeiro Pereira (José Manuel Da Silva Chaves Ribeiro Pereira); Miguel Abreu de Almeida Mendes (Miguel Abreu de Almeida Mendes)

Published in

June 28, 2024

Abstract

Swirl is a method to aerodynamically stabilize flames by: generating recirculation zones that ensure continuous ignition; increasing mixing and combustion efficiency that generally decreases pollutant emissions. The aim of this work was to find optimal operating conditions of a double swirl hydrogen/natural gas burner using fast and reliable CFD and numerical models as part of a research project funded by Universal H2. Turbulence models and 2D RANS axisymmetric steady conditions simulated using Star-CCM (Siemens, version 2306.0001R8) were validated considering temperature profiles. DRM19 was the chemical kinetics mechanism used and Steady Laminar Flamelet combustion model suits best the accuracy/time trade-off of the project when compared to the Eddy Dissipation Concept model. NO emissions showed satisfactory agreement with the experimental values. CO emissions were not properly estimated due to axisymmetry conditions. Numerical models supported the CFD code regarding fuel-air mixing properties and specific temperature, volumetric flow rate or delivered heat targets. Reynolds Stress Model (Elliptic Blending) presented the lowest global error (24%). Simulations showed an increase in internal aeration (100% and 75% for hydrogen and natural gas, respectively) and swirl vane angle (from 45º to 60º) respect pollutant emissions' regulation limits (phi (0.4; 0.5; 0.6; 0.7), 5 kW) due to better mixing of air-fuel which was confirmed experimentally. Powers of 10 kW and 20 kW were tested numerically and internal aeration must decrease to 25% to counter-balance excessive mixing and respect NO emissions. The burner operates safely, effectively and can be used in industrial contexts within the conditions tested.