Current ambitious targets of transport utilized fossil fuels replacement pose a considerable challenge while transportation affordability, energetic and precious materials security are to be maintained. Most of current solutions oriented towards passenger cars fossil fuel replacement by more renewable resources are dependent on one superseding method only. On other hand, each of them exhibits some drawbacks and benefits while a reasonable combination could mitigate number of limitations and include many advantages. Such a solution could be usage of a wide range of liquid fuels from renewable resources in a suitable spark ignition engine accompanied by common battery electricity storage.
The aim of this experimental work was to develop and demonstrate possibilities and results of an uncomplex engine adaptation to a wide range of fuels obtainable from renewable resources suitable as a range extender to commonly proposed electric cars. The approach chosen used standard gasoline as a starting fuel followed by switching to neat alcohol-based fuel. This goal embraced significant modifications to engine fuel system, utilization of different control system and proper fuel switching procedure and control of air to fuel ratio. Afterwards, the engine successfully operated under quasi-stationary conditions, including wide-open throttle (WOT) conditions.
The results indicate that a broad spectrum of alcohol-based fuels can be effectively utilized in a properly modified engine functioning as a range extender. Carbon dioxide emissions from fossil fuels were typically below 100 g per cold start.
The fuel substitution did not require any fuel-specific modifications to the engine or fuel system. Minor variations in the air-to-fuel ratio were observed when introducing fuels with a higher hydrogen-to-carbon (H/C) ratio, due to the use of a Heated Exhaust Gas Oxygen (HEGO) sensor for air-fuel ratio control.
Consequently, a change in the switching voltage threshold (a control system constant) was demonstrated, with emphasis on compliance with current stringent emission standards.