Using alcohol fuels in dual fuel operation of compression ignition engines: a review

摘要

Because of global warming and increasing air pollution, alternative fuels are increasingly being considered for use in internal combustion engines (ICEs). Among the alternatives, alcohol fuels seem very interesting. They can be produced in a renewable way and possess certain advantageous properties that give them the potential to lower pollutants and CO2 emissions from ICEs. Methanol and ethanol are the most researched alcohols today. In fact, in some areas of the world, gasoline is blended with methanol or ethanol for use in spark ignition (SI) engines. These alcohols are ideally suited for SI engines because of their high octane number (low tendency to knock). That makes them, however, not very well suited for compression ignition (CI) engines which require high cetane number fuels. There exist, however, CI engine technologies that burn alcohol fuels. One of these technologies is Dual Fuel (DF) operation. In DF operation, the engine runs effectively on two fuels. There exist several concepts to achieve this. One of these is to inject a mixture of diesel and alcohol fuel directly into the cylinder. Another is to separately inject diesel and alcohol fuel directly into the cylinder. A third concept (so-called fumigation) is to inject the alcohol fuel into the intake and the diesel directly into the cylinder (the homogeneous alcohol-air mixture is then ignited by a pilot injection of diesel). The paper will provide an overview of the literature regarding this fumigation concept. This work has been carried out as a part of the LeanShips project. LeanShips stands for 'Low Energy And Near-to-Zero emission Ships'. It is a Horizon 2020 (H2020) project funded by the European Commission aimed at developing green shipping technologies and bringing these to the market. One of the Work Packages of the LeanShips project, 'Demonstrating the Potential of Methanol as an Alternative Fuel' aims to demonstrate a high-speed heavy-duty marine diesel engine converted to Dual Fuel (DF) operation on methanol (and diesel) while achieving significant reductions of emitted pollutants.