Phase Separation Control System for Gasoline-Methanol Blends in Passenger Cars

Gasoline-methanol blends, without stabilizing additives, phase separate at low temperatures and/or in the presence of water. This has been, among others, a restrictive factor for the utilization of gasoline-methanol blends in the single tank of a passenger car equipped with an S.I. engine, especially in areas of seasonable low temperature conditions like in Canada. A phase separation control system (PSC) has been developed which can be retrofitted to an engine equipped with an oxygen sensor controlled closed loop carburettor. Blends up of M25 have been utilized while maintaining the flexibility to operate the engine on straight gasoline. Both fuels are carried in one tank and the PSC delivers to the engine after start up and warm up a proportional and stable blend, while during cold start and at phase separated conditions, straight gasoline (gasoline rich phase) is utilized. Data of cold starts on different methanol blends (M5 to M30) as performed on a dynamometer are presented indicating the warm up operation and the system limits. The PSC system has been installed in a vehicle and first results of cold starts and driveability testing indicate that the fuel system operates satisfactorily. Compatibility problems with materials exposed to the blend have been encountered and will be reported.