Alternative fuels for spark-ignition engines: mixing rules for the laminar burning velocity of gasoline-alcohol blends

Experimental measurements of the laminar burning velocity are mostly limited in pressure and temperature and can be compromised by the effects of flame stretch and instabilities. Computationally, these effects can be avoided by calculating one-dimensional, planar adiabatic flames using chemical oxidation mechanisms. Chemical kinetic models are often large, complex and take a lot of computation time, and few models exist for multi-component fuels. The aim of the present study is to investigate if simple mixing rules are able to predict the laminar burning velocity of fuel blends with a good accuracy. An overview of different mixing rules to predict the laminar burning is given and these mixing rules are tested for blends of hydrocarbons and ethanol. Experimental data of ethanol/n-heptane and ethanol/n-heptane/iso-octane mixtures and modeling data of an ethanol/n-heptane blend and blends of ethanol and a toluene reference fuel are used to test the different mixing rules. Effects of higher temperature and pressure on the performance of the mixing rules are investigated. It was found that simple mixing rules that consider only the change in composition are accurate enough to predict the laminar burning velocity of ethanol/hydrocarbon blends. For the blends used in this study, a Le Chatelier's rule based on energy fractions is preferable because of the similar accuracy in comparison to other mixing rules while being more simple to use

Efficiency and emissions of a high-speed marine diesel engine converted to dual-fuel operation with methanol

Climate change and global warming, a growing maritime sector, and the roadmap away from fossil fuels towards a CO2 neutral economy are driving innovations and technology developments. Fuel selection criteria such as sustainability, scalability and storability, lead to the selection of methanol as a viable alternative for fossil fuels. In LeanShips, a European Horizon 2020 Innovation Project, the conversion and operation of a high speed marine diesel engine on dual fuel methanol/diesel has been demonstrated. This paper presents the applied conversion solution, its impact on combustion characteristics, and the results of dual fuel methanol/diesel operation on engine performance parameters such as brake thermal efficiency (BTE), NO and soot emissions. The results were recorded at different engine speeds ranging from 1000 to 2000 rpm and for varying loads, in total 28 load points were tested. At each load point the methanol energy fraction was increased until the boundaries for substitution were reached. In dual fuel operation a relative increase of 12% in BTE was recorded and for respectively NO and soot emissions average decreases over the entire load range of 60% and 77%. The maximum obtained methanol energy fraction and diesel substitution ratio amounted respectively to 70% and 67%

”Dangerous fuels” for cars : a way to save the world

Flame or combustion gave humans healthy food, protection, heat, light, and so on. The combustion also gave the power for a car to move from point A to point B. Most of the vehicle in the world now are powered by the internal combustion engines. The engine converts the chemical energy stored in the reactant, i.e. mixture of fuel and air, into thermal and mechanical energy. Engines and fuel technology are scalable, cheap and compact. They are also can be produced in a sustainable way or in a carbon-neutral cycle. Therefore, internal combustion engines are still the main power source for the current and for future transport systems. Renewable methanol (or synthetic methanol) is a great fuel for internal combustion engines thanks to its interesting properties and high fuel production efficiency. Methanol is also considered as a hydrogen carrier fuel, which can be easily generated on-board using engine exhaust heat. The present work focuses on the thermochemical recuperation for methanol reforming to further improve the engine efficiency and reduce harmful emissions