Boehman and his team are planning to test DME-blend fuel in a Defender model, Champion motor coach with an International Corp. chassis and a Navistar engine. The shuttle bus, which seats 22 passengers and is handicapped accessible, was purchased jointly by Penn State's fleet services and Boehman's grants. The researchers have begun to determine the baseline characteristics of the motor coach when run on standard diesel fuels. At the same time they are testing a variety of DME fuel blends on a test-bed engine. According to Boehman, DME would make a poor replacement for gasoline because its octane rating is very low.
Octane rating measures a fuel's resistance to spontaneous sparking.
However, diesel fuels are cataloged by cetane rating, a measure of a fuel's ease of spontaneous combustion once the proper temperature and pressure are reached. Diesel fuel has a cetane of 45 and dimethyl ether has a cetane of 55. Once the baseline and laboratory fuel tests are completed sometime next year, the researchers will adapt the motor coach for use with the DME fuel and will evaluate engine response, emissions and wear under normal usage.