Literature Review and Suggestions on Alcohol Engines with Ether as Ignition Impropvers

Rapport, 1996

The ignition improvers available on the market are rather expensive, toxic and, as expected, highly explosive. They are normally used in two different ways: mixed directly into the base fuel leading to a soluble fuel or fed separately into the engine. A suitable emulsifying agent is often required when the soluble fuel is considered. Considering the latter possibility, the two fuel system is more complex and costly, and therefore not so commonly used. In order to use the ignition improvers sufficiently they have to meet some requirements, especially with regards to the minimum admixture quantity, sufficient solubility and storability in alcohol, lubricating properties, minimum toxicity etc. Dissolved ignition improvers as “Beraid” or “Avocet” have been successfully used in Volvo and Scania diesel engines. Different investigations and engine design optimizations for running on ethanol with beraid. as ignition improver have been done at the Department of Thermo and Fluid Dynamics (CTH) through different projects and studies. The results of these studies are reported in different publications of the Swedish Transport & Communications Research Board (KFB) and CTH- TFD internai papers. This possibility to use ethers, such as Dimethyl Ether (DME) and Diethyl Ether (DEE), when running the engine on methanol and ethanol respectively, was studied and followed up with an experimental project in a modified alcohol engine Volvo AH10A245. The aim of the project was to verify the possibility to use ethers, from an economical point of view, instead of ignition improvers. If a positive result is achieved, the possibility to generate ethers in an onboard reactor will be considered. DME can be easily produced by the exothermic dehydration of methanol over an acid catalyst according to the reaction