Fuelling of an automotive engine on dimethyl ether (DME)

摘要

AbstractudThis research is based on development of a small compact Low Pressure Dimethyl Etherud(DME) fuelling system with the scope of one day being retrofitted to a diesel Light DutyudVehicle (LDV). The development of the Low Pressure DME fuelling system is discussed along with the engine injector haracteristics, the energy release, and the NOx emissions. The recorded data was compared to a previous DME fuelling system and conventional diesel results. The report discusses in detail the complete design phase of the Low Pressure DME system, with emphasis on the delivery pressure and portability of the system. The testing phase was run using a 1330cc PH2 Lister Petter diesel engine, with the Low Pressure DME fuelling system connected to the inlet of the original diesel injector fuel pumps. Three individual tests were run, ranging from 1100 rpm to 1800 rpm, at loads of 25Nm, 35Nm and 45Nm. Engine performance and emission data were recorded for each case, with emphasis placed on the fuel injector line pressure. The results obtained indicated that the bulk modulus of the fuel played an important role when it came to fuel injector performance. Injector timing was also identified as having a significant effect. The energy released, while running on the Low Pressure DME fuelling system, clearly indicated that the maximum peak occurred well after top dead centre, this in turn influenced the cylinder pressure which ultimately reduced the usable power. From the NOx emissions it was seen that running the engine on DME, the concentration levels started off high for low engine speeds and rapidly tapered down as the speed increased. The Low Pressure DME fuelling system produced the lowest NOx concentration levels for high engine speeds and especially high engine loads. As a whole the Low Pressure DME fuelling system produced satisfactory results and showed definite potential for future development.