Innovative surrogate combustion model for efficient design of small-scale waste mono-incineration systems

Žnidarčič, Anton (author), Katrašnik, Tomaž (author), Seljak, Tine (author)

Small-scale thermal treatment systems can provide environmentally improved sewage sludge treatment due to processing sludge locally, which lowers transport costs and emissions. However, the combined effect of confined volume and complex sludge properties makes achieving strict regulations on flue gas emissions and end-ash composition challenging. System development thus requires the use of advanced, 3D CFD simulation supported studies. An important step forward regarding these is the application of combustion models which introduce tailored surrogate fuels and apply detailed chemical kinetics to achieve a high-fidelity combustion description in confined volumes. In relation to this, the paper presents an innovative computationally efficient sewage sludge surrogate-based combustion model capable of defining surrogates, tailored to sewage sludge, and capable of providing detailed insight into reaction zone evolution in small-scale sludge incineration systems. The validity of the proposed model and surrogates is confirmed via simulated temperatures differing from measurements in the small-scale system for less than 30 K. The validated model of a small-scale system is used in the parametric analysis of variable air–fuel ratios, higher fuel moisture presence, varying bed temperature, and varying thermal power to enable unprecedentedly accurate and efficient definition of design features of small-scale systems and to provide key guidelines for operation optimization.

• Language: English
• Keywords: sewage sludge, combustion, surrogate model, combustion control, chemical kinetics, 3D CFD
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2025
• Number of pages: 33 str.
• Numbering: Vol. 13, iss. 10, art. 3170
• PID: 20.500.12556/RUL-174604
• UDC: 621.431
• ISSN on article: 2227-9717
• DOI: 10.3390/pr13103170
• COBISS.SI-ID: 251982083
• Publication date in RUL: 07.10.2025

Record is a part of a journal

• Title: Processes
• Shortened title: Processes
• Publisher: MDPI
• ISSN: 2227-9717
• COBISS.SI-ID: 523353113

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.