In this ninth installment of a 14-part series of monthly articles, The Combustion Institute recognizes the 2017 Distinguished Papers selected from among the scientific papers presented during the 36th International Symposium on Combustion. Congratulations to M. Rieth, A.G. Clements, M. Rabaçal, F. Proch, O.T. Stein, and A.M. Kempf for winning the DPA in the Solid Fuel Combustion colloquium.

The authoritative paper, Flamelet LES modeling of coal combustion with detailed devolatilization by directly coupled CPD, explores devolatilization and volatile combustion in pulverized coal combustion (PCC) within time- and large-scale resolving numerical simulations, referred to as large eddy simulations (LES). The scientific team developed numerical models that can help with the design and optimization of combustion processes, such that pollutant and greenhouse gas emissions can be reduced and resources can be used more economically.

As coal particles are subjected to a hot combustor or furnace environment, volatile matter bound in the solid coal particle is released to the gas surrounding the particle. These volatile gases have a complex composition of different species such as carbon monoxide, methane and heavier tar. Fundamental difficulties in the representation of the devolatilization process are the rate at which volatiles are released, which mainly depends on the heating rate of the coal particle and the coal structure, as well as the composition of the volatile gas. The latter is not only dependent on the coal type used but also on the heating history of the coal particle.

The scientific team’s paper has improved a state-of-the-art coal combustion simulation. The team included a flamelet model developed for PCC and they directly plugged a more detailed Chemical Percolation for Devolatilization (CPD) model into the LES. Testing was performed on a lab scale coal jet flame of the Central Research Institute of Electric Power Industry (CRIEPI) in Japan. The flamelet model allows for the incorporation of detailed chemistry effects at a reduced cost by assuming that a turbulent flame can be approximated by localized laminar flames embedded in the turbulent environment. The team showed that both measures improved the simulation. In particular, the detailed devolatilization model leads to a very different instantaneous particle devolatilization behavior compared to the simple fitted model, which might need to be considered in the future for detailed pollutant predictions.

The immediate impact of the paper provides a better understanding of the CRIEPI jet flame that has evolved to be a standard numerical simulation test case for PCC. In addition, combustion research will benefit from the knowledge that the application of detailed devolatilization models is feasible in LES and that the flamelet model that has been very popular for purely gaseous flames can be applied in the PCC context. In the long-term, the methods developed may be used by researchers and scientists to design new combustors and furnaces with reduced pollutant emissions and a more efficient usage of resources.

Beneficiaries of the scientific team’s findings include academic researchers who can use this research to advance their work. In the future, beneficiaries may include engineers and researchers in the power and process industry e.g., power plant manufacturers or the steel industry.

The paper’s research was mainly conducted at the Chair for Fluid Dynamics, Institute of Gas Dynamics, Universität Duisburg-Essen, Germany. Contributions came from researchers at the Universität Stuttgart, Germany, Instituto Superior Técnico, Portugal, and the University of Sheffield, United Kingdom. The main research for the paper began in the summer of 2015 and was completed in late 2015.

About 1,300 papers were submitted to the 36th Symposium in 14 combustion science colloquia. Those papers were categorized by teams of colloquium coordinators and co-chairs, and then distributed to approximately 1,000 scientific reviewers. One paper in each discipline was awarded the recognition of Distinguished Paper.

The 14 Distinguished Papers undergo committee review for consideration to receive the Silver Combustion Medal that will be awarded during the 37th Symposium in Dublin, Ireland. A paper selected for this honor exemplifies quality, achievement, and significance to advance a field of combustion science. Distinguished papers are selected biennially from among the scientific papers presented during the International Symposium on Combustion and accepted for publication in the Proceedings of The Combustion Institute.