DME-methanol fueled RCCI engine testing and development

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Compression ignition engines provide superior thermal efficiency because of the high compression ratio. This translates into better fuel economy and lower carbon dioxide emissions. The drawback of traditional diesel engines is that direct injection produces fuel-rich zones in the cylinder that result in the production of particulate matter (soot) and lean high-temperature zones that produce high NOx levels. Dual fuel engines that operate under more homogeneous conditions and produce lower combustion temperature circumvent this problem. The project will involve developing and testing a compression ignition dual fuel engine using dimethyl ether as the reactive pilot fuel and methanol as the primary fuel. Both these fuels are cleaner burning than diesel and can be derived from natural gas or biomass. One of the key issues is the ignition timing for this new combination of fuels. The ignition timing can be varied during operation via the injection timing to produce optimum efficiency. However, a better understanding is required for modeling of the in-cylinder combustion process. A simultaneous study looking at dimethyl ether spray pattern and ignition will be performed in a shock tube. The shock tube will be used to condition the methanol-air to typical engine temperature and pressure conditions at the end of the shock tube. During this time dimethyl ether will be sprayed into the mixture and the spray pattern and ignition will be recorded using high-speed video.