|An early sketch of the OMNIVORE single-cylinder concept. Click to enlarge.|
Lotus Engineering, the automotive consultancy division of Lotus, will collaborate with Queen’s University Belfast (QUB) and Jaguar Cars Ltd to develop an engine which maximizes fuel efficiency when running on renewable fuels. The OMNIVORE concept will employ novel engine architecture to achieve a high thermal efficiency when fuelled on any alcohols or gasoline. The OMNIVORE engine is being targeted for flex-fuel operation with a higher degree of optimization and fuel-efficiency than is possible with existing architectures.
The architecture features an innovative variable compression ratio system and uses a loop-scavenged two-stroke operating cycle with direct fuel injection operating in HCCI (homogeneous charge compression ignition) mode. In an earlier presentation on the concept, Lotus said that it believed compression ratios ranging from 8:1 to 40:1 are possible.
The project is sponsored by the UK Defra (Department for the Environment and Rural Affairs) and the Department of the Environment Northern Ireland (DOE NI) through the Renewable Materials LINK Programme. Lotus Engineering is currently undertaking a design study and the build of a single cylinder research engine for completion in January 2009. Vehicle modelling will validate the reduction in vehicle CO2 emissions. Queen’s University of Belfast’s School of Mechanical and Aerospace Engineering is contributing its expertise in engine simulation, and Jaguar Cars Ltd is a consultative partner at all stages of development.
The OMNIVORE program complements the recently unveiled Lotus Exige 270E Tri-fuel (earlier post) as part of Lotus’ research to understand the complex combustion process involved in running on mixtures of alcohol fuels and gasoline, an important element for a successful transition from today’s fuels to the synthetic fuels of the future, said Lotus.
The requirement to operate on gasoline in today’s flex-fuel engines limits their thermal efficiency when operating on alcohol fuels. However, the physical and chemical properties of alcohols, when compared to gasoline, provide the potential for higher thermal efficiency operation to be achieved. This single-cylinder research engine will investigate a highly thermal efficient combustion system that optimizes engine performance to fully exploit the properties of both gasoline and alcohol fuels and maximize efficiency.—Geraint Castleton-White, Head of Powertrain at Lotus Engineering
In the US, Argonne National Laboratory’s Transportation Technology R&D Center has undertaken a similar project to develop an “omnivorous engine”. The Argonne project seeks to combine in-cylinder measurement technology and advanced controls to optimize spark timing, the quantity, and the timing of injected fuel to produce an engine that will be able to run on any liquid spark ignition fuel with optimal efficiency and low emissions. (Earlier post.)