| Title: | Modeling of a premixed hydrogen-air combustion in a gas condensing boiler : doctoral dissertation |
|---|
| Authors: | ID Jaeger, Marc (Author)
ID Samec, Niko (Mentor) More about this mentor... 
ID Hriberšek, Matjaž (Comentor) |
|---|
| Files: |  DOK_Jäger_Marc_2025.pdf (11,49 MB)
MD5: DBE9360F4BE732A73282CBF31E014DF0
|
|---|
| Language: | English |
|---|
| Work type: | Doctoral dissertation |
|---|
| Typology: | 2.08 - Doctoral Dissertation |
|---|
| Organization: | FS - Faculty of Mechanical Engineering
|
|---|
| Abstract: | This work addresses the urgent need for decarbonization of heating sector, focusing
on the potential of hydrogen-air combustion in gas condensing boilers. In the field of
gas condensing boilers, groups of holes or slits can be used in perforated burner
surfaces, providing a possible solution to the challenge of hydrogen air combustion.
Real burners are always adjacent to an area with non-existent combustion, which can
lead to a disturbed flame pattern. For this reason, a comparison between single-slit
and multi-slit perforated flame holders with a significantly reduced structure
temperature with a hydrogen-air premix is carried out as part of this study. Using Ansys
Fluent, a 2D simulation approach is employed to analyze laminar flame stability behind
a perforated flame holder. Inlet conditions consider fully premixed and homogenous
distributed mixtures as well as non-homogeneous premixed mixtures, with variations
in pressure, velocity, and mixing degree. The model examines various slit-burner
configurations and flashback behaviors based on an actual geometric shape used in a
gas heating device. It has been found that with finite multi-slit burners, the bulk flow
rates at the critical flashback point are 30-50% higher compared to infinitely
symmetrical burners. A further deterioration of 32% is to be expected due to real
mixture quality fluctuations and inhomogeneous inflow conditions.
The numerical model was validated using a prototype heat exchanger and a
production-ready mixture preparation system in combination with various burner
geometries.
From a practical standpoint, the results provide clear guidance for burner design. Long
and narrow holes with moderate spacing -ideally at least one diameter apart- promote
flame stability while maintaining a compact configuration. In clustered geometries,
optimizing the number of flow passages can prevent local overheating and enhance
operational robustness. For complex or thermally sensitive geometries, the use of 3D
CFD simulations with conjugate heat transfer (CHT) coupling is strongly advised to
ensure accurate and safe designs. Additionally, at higher air excess ratios, the current
numerical model becomes less accurate due to intensified preferential diffusion and
Soret effects, highlighting the need for a 3D CFD approach using the Konnov reaction
mechanism.
Finally, the findings demonstrate the model's potential for designing efficient surface
stabilized burners and lay the groundwork for future 3D simulations in the pursuit of
sustainable heating solutions. |
|---|
| Keywords: | CFD, hydrogen combustion, flashback, flame stability, perforated flame holder, gas condensing boiler, experimental flashback measurements |
|---|
| Place of publishing: | Maribor |
|---|
| Place of performance: | Maribor |
|---|
| Publisher: | [M. Jäger] |
|---|
| Year of publishing: | 2025 |
|---|
| Number of pages: | XXI, 190 str. |
|---|
| PID: | 20.500.12556/DKUM-93113 |
|---|
| UDC: | [662.61:662.769.2]:697.245(043.3) |
|---|
| COBISS.SI-ID: | 266347523 |
|---|
| Publication date in DKUM: | 20.01.2026 |
|---|
| Views: | 190 |
|---|
| Downloads: | 18 |
|---|
| Metadata: |    |
|---|
| Categories: | KTFMB - FS
|
|---|
|
:
|
Copy citation |
|---|
| | | | Average score: | (0 votes) |
|---|
| Your score: | Voting is allowed only for logged in users. |
|---|
| Share: |  |
|---|
Hover the mouse pointer over a document title to show the abstract or click
on the title to get all document metadata. |
