Orbital Introduces FlexDI Injection Technology
27 October 2007
Australia-based Orbital Corporation introduced its new FlexDI modular direct injection fuel system technology at the 5th International Clean Vehicle Exhibition and Forum in Beijing. Polaris Industries is the first customer to go into series production with FlexDI, applying it in the Patriot Engine. (Earlier post).
Orbital’s core technology—the Orbital Combustion Process (OCP)—uses air-assisted, low-pressure direct fuel injection rather than high-pressure injection to atomize the fuel charge. With OCP, fuel is first metered into an injector pre-chamber via a conventional automotive port injector (MPI), and then delivered into the combustion chamber with the assistance of air at pressure.
The air-assisted injector decouples the fuel metering and delivery events, thereby assisting the dynamic range of the injector, according to Orbital. The Orbital DI system creates a precisely-controlled, finely atomized fuel cloud allowing engines to run with greater fuel efficiently and with reduced emissions output.
The FlexDI system enables engine manufactures to develop one spark-ignited engine family capable of handling different fuel types through changes to the fuel system. This opens up the potential for manufacturers to offer customers gasoline, ethanol, CNG, hydrogen and SI heavy-fuelled engine variants utilizing the same base engine design. FlexDI can also be configured for Bi-Fuel or Tri-Fuel operation.
FlexDI offers a stratified lean combustion system for gasoline applications. Variable injection strategy and phasing enables many different combustion modes including ultra lean; homogeneous lambda=1; stratified lean; low NOx combustion and HCCI.
FlexDI also allows high EGR combustion for enhanced fuel consumption through reduced pumping losses and higher dynamic compression ratios. FlexDI can tolerate up to 45% EGR.
Orbital says that FlexDI is suited for boosted applications with lower knock and improved low speed torque capability making engine downsizing possible. Low speed driving is achieved with a unique lean-burn combustion mode improving city and stop/start driving fuel economy.
For hydrogen combustion, the FlexDI systems offers a unique solution. Current Hydrogen IC engines have issues with burn-rate control due to the very high speed of hydrogen combustion. The control to date for combustion problems and NOx production is to operate engines at lean air fuel ratios—which reduce specific power.
FlexDI can use its dual injectors to direct inject both hydrogen and water in the same spray. This gives more control over burn-rates and NOx emissions and provides the ability to run lambda=1 at high load conditions. Hydrogen IC specific outputs can be the same as, or better than, gasoline (up to 117% of gasoline), according to Orbital.
Separately, Orbital announced it is in the final stages of delivering an engineering development program to improve the reliability and performance of Liquefied Natural Gas (LNG) dual fuel systems fitted to Caterpillar C-15 engines used by Australian line haul operators.
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