Combustion Process Improvement of a Wood Gas Specific ICE for Sustainable Heat and Power Supply

Abstract

A significant contribution to achieving the goals of Paris' climate agreement and be-coming greenhouse-gas-neutral by 2050 can provide the utilization of regenerative fuels in internal combustion engines (ICE) for traffic and stationary power generation. More precisely, the CO2-neutral wood gas from air-wood gasification as a fuel for high-speed engines of decentral Combined Heat and Power Plants (CHP), e.g., GLOCK ecotech biomass power plants, enables sustainable and carbon-neutral heat- and elec-tricity-supply. However, efficient engine operation is challenging due to the adverse properties of wood gas, such as fluctuations in gas composition, high content of inert gases, and low heat value of the fresh charge. Therefore, this research project aims to improve the wood gas ICE efficiency of the biomass power plant (P<50kWel). In this paper, the methods and results of a related combustion process development are de-scribed, including an analysis of the efficiency and the pollutant emissions such as NOX and CO. At the Institute for Powertrains and Automotive Technology (IFA) of TU Wien, a single-cylinder engine test bench was set to investigate the combustion process. A fully flex-ible gas composition mixer provides the ICE with the gas mixture and reproduces the biomass power plant's gas supply, avoiding the sluggish behavior of real gasification and long start-up processes. The combustion concept must apply a lean combustion strategy to improve thermal efficiency and meet emission targets. By developing a combustion chamber shape for optimized charge movement, including adjustment of the compression ratio, a stable combustion process for heavily diluted, premixed fresh charge could be achieved, leading to an improvement in thermal efficiency of 6.4%. Furthermore, "Near-Zero NOX Emissions" can be achieved. By applying an effective exhaust gas aftertreatment, low CO and THC emissions can be realized, meeting the emission targets.