Combustion in the future: The importance of chemistry

Abstract

Combustion involves chemical reactions that are often highly exothermic. Combustion systems utilize the energy of chemical compounds released during this reactive process for transportation, to generate electric power, or to provide heat for various applications. Chemistry and combustion are interlinked in several ways. The outcome of a combustion process in terms of its energy and material balance, regarding the delivery of useful work as well as the generation of harmful emissions, depends sensitively on the molecular nature of the respective fuel. The design of efficient, low-emission combustion processes in compliance with air quality and climate goals suggests a closer inspection of the molecular properties and reactions of conventional, bio-derived, and synthetic fuels. Information about flammability, reaction intensity, and potentially hazardous combustion by-products is important also for safety considerations. Moreover, some of the compounds that serve as fuels can assume important roles in chemical energy storage and conversion. Combustion processes can furthermore be used to synthesize materials with attractive properties. A systematic understanding of the combustion behavior thus demands chemical knowledge. Desirable information includes properties of the thermodynamic states before and after the combustion reactions and relevant details about the dynamic processes that occur during the reactive transformations from the fuel and oxidizer to the products under the given boundary conditions. Combustion systems can be described, tailored, and improved by taking chemical knowledge into account. Combining theory, experiment, model development, simulation, and a systematic analysis of uncertainties enables qualitative or even quantitative predictions for many combustion situations of practical relevance. This article can highlight only a few of the numerous investigations on chemical processes for combustion and combustion-related science and applications, with a main focus on gas-phase reaction systems. It attempts to provide a snapshot of recent progress and a guide to exciting opportunities that drive such research beyond fossil combustion.

Numerical Investigation on the Effect of the Oxymethylene Ether-3 (OME3) Blending Ratio in Premixed Sooting Ethylene Flames

“…Synthetic fuels produced with renewable energy and, in particular, oxygenated fuels can improve both the overall carbon balance and local emissions, such as soot particles, without extensively modifying the present combustion devices. Oxymethylene ethers (OMEs), which are promising synthetic fuel candidates (Kohse-Höinghaus, 2021), deployable e.g. in self-ignition engines, have been proven in recent studies (Ferraro et al, 2021;Tan et al, 2021) to significantly reduce the sooting tendency of blended fuel flames.…”

Comparison of Flame Propagation Statistics Based on Direct Numerical Simulation of Simple and Detailed Chemistry. Part 2: Influence of Choice of Reaction Progress Variable

“…The use of fossil resources for the supply of primary energy leads to increasing concerns about emissions and their environmental, and health impact [1]. However, the challenges laid out by the Paris Agreement are daunting [2] and the time scales to phase out the existing infrastructure are substantial [1].…”

“…The use of fossil resources for the supply of primary energy leads to increasing concerns about emissions and their environmental, and health impact [1]. However, the challenges laid out by the Paris Agreement are daunting [2] and the time scales to phase out the existing infrastructure are substantial [1]. Therefore, combustion remains a topic of considerable importance and Direct Numerical Simulations (DNS) offer valuable insights into the physical and thermochemical phenomena, as reviewed for the early DNS work by Poinsot et al [3], and more recently by Chen [4].…”

Experimental and Numerical Study on the Sooting Behaviors of Furanic Biofuels in Laminar Counterflow Diffusion Flames

“…In the foreseeable future, internal combustion engines (ICEs) burning liquid fuels will still be prevalent, especially in the transport sector with applications for heavy duty, off-road, and military vehicles [1]. However, conventional ICEs also face the challenges of petroleum shortage and the ever increasingly stringent regulations on greenhouse gases (GHGs) and other pollutant emissions such as soot.…”