Distributed combustion of paraffinic and highly oxygenated renewable fuels

Rosec, Žiga (author), Katrašnik, Tomaž (author), Chong, Cheng Tung (author), Seljak, Tine (author)

Stringent emission regulations are driving the development of advanced combustion technologies that significantly reduce harmful pollutants and enable the use of fuels with lower lifecycle CO▫$_{2}$▫ emissions. This study investigates the performance of two renewable liquid fuels—glycerol and hydroprocessed esters and fatty acids (HEFA)—across the full transition from conventional to distributed combustion in an experimental gas turbine setup. Distributed combustion is achieved via high external exhaust gas recirculation (EGR) rates, progressively lowering the oxygen concentration in the primary combustion air to 10 vol%. Under distributed combustion conditions, both fuels exhibit markedly reduced emissions of nitrogen oxides, carbon monoxide, and particulate matter, with nitrogen oxides levels reduced two-fold and particulate matter emissions lowered by two orders of magnitude. The transition from conventional to distributed combustion with HEFA reveals a highly non-linear emission response to increasing EGR rates, with a pronounced emission peak occurring between 60-70 % EGR. Glycerol, on the other hand, is significantly less sensitive to mid-range EGR rates and is also less responsive to emission reduction within distributed combustion regime, while it still maintaining the benefits of low emission operation in conventional combustion regime. The study for the first time analyzes uninterrupted transitioning from 0 % EGR to 80 % EGR in a realistic, continuous pressurized combustion system with 90 kW of thermal input and demonstrates the phenomena present during onset of distributed combustion regime with two major groups of renewable fuels.

• Language: English
• Keywords: exhaust gas recirculation, EGR, distributed combustion, glycerol, HEFA, MILD, emissions
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2026
• Number of pages: 15 str.
• Numbering: Vol. 405, pt. A, art. 136523
• PID: 20.500.12556/RUL-182183
• UDC: 621.43:536.45
• ISSN on article: 0016-2361
• DOI: 10.1016/j.fuel.2025.136523
• COBISS.SI-ID: 276688643
• Publication date in RUL: 29.04.2026

Record is a part of a journal

• Title: Fuel
• Shortened title: Fuel
• Publisher: Elsevier
• ISSN: 0016-2361
• COBISS.SI-ID: 37399

Licences

• License: CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
• Link: http://creativecommons.org/licenses/by-nc-nd/4.0/
• Description: The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.

Secondary language

• Language: Slovenian
• Keywords: recirkulirani izpušni plini, distribuirano zgorevanje, glicerol, HEFA, MILD, emisije