Research on the combustion of alcohol-gasoline blends

Volvo flex-fuel engine

Features

  • Based on a naturally aspirated 4-cylinder gasoline engine with port fuel injection
  • Runs on both gaseous (e.g. hydrogen, methane) and liquid fuels (e.g. gasoline, methanol, ethanol)
  • Variable intake valve timing
  • MoTeC M800 engine control units that controls fuel injection and ignition timing
  • Measurements of brake torque, fuel consumption, temperatures, emissions and crank-angle resolved intake, cylinder and exhaust pressure

Overview of Volvo flex-fuel engineDetail of Volvo flex-fuel engine

Figure 1: Overview (l.) and detail (r.) of the Volvo flex-fuel engine bench

Applications

Thanks to its fuel flexibility the Volvo Flex-Fuel is very suitable for comparing the performance and emissions of different alternative fuels in a production type spark-ignition engine. For this reason the engine is used both as an educational and a research tool.

As an example of research work, Figure 2 shows some results published in a recent Master thesis. The brake thermal efficiency of gasoline, methanol and hydrogen are compared at 40 Nm and for a range of engine speeds. The higher efficiency of methanol compared to gasoline can be partly explained by its faster combustion, as can be seen in the log p-log V diagram on the right.

Indicated thermal efficiencyLog p - Log V diagram

Figure 2: Comparison of the brake thermal efficiency of H2, methanol and gasoline at 40 Nm

Audi/NSU single cylinder engine

Features

  • Based on a experimental single cylinder compression ignition engine with direct injection
  • Converted for spark-ignition engine operation
  • Runs on both gaseous (e.g. hydrogen, methane) and liquid fuels (e.g. gasoline, methanol, ethanol)
  • Compressor and backpressure valve to simulate turbocharging
  • Exhaust gas recirculation (EGR)
  • MoTeC M4Pro engine control unit controls fuel injection and ignition timing.
  • Measurements of brake torque, fuel consumption, temperatures, emissions and crank-angle resolved intake, cylinder and exhaust pressure.

Overview of Audi single cylinder engineDetail of Audi single cylinder engine

Figure 1: Overview (l.) and detail (r.) of the Audi/NSU engine bench

Applications

Thanks to its fuel flexibility the Audi is very suitable for comparing the performance and emissions of different alternative fuels in a spark-ignition engine. The combination of turbocharging and EGR make it possible to research different load control strategies.

As an example of research work, Figure 2 shows some results published in a recent Master's thesis. Different load control strategies for methanol are compared at 1500 rpm. Normal throttled operation is compared against a strategy with wide open throttle (WOT) where load is controlled using varying amounts of exhaust gas recirculation (EGR). The WOT EGR strategy results in slightly higher indicated thermal efficiencies due to lower pumping losses, as can be seen in the log p-log V diagram.

Log p - Log V diagram

Figure 2: Comparison of different load control strategies: throttled operation and WOT EGR operation.