Volkswagen Group developing lean-burn combustion for monovalent natural gas engine as part of $27M EU GasOn research project
10 July 2017
Volkswagen Group Research and its partners in the EU-funded GasOn research project are developing an innovative monovalent natural gas engine. Based on a 2.0-liter diesel engine, the unit permits very high compression. Extremely lean combustion (λ~2) leads to low consumption and initially to very low engine-out emissions.
Initial test results reported to the consortium for the period through October 2016 suggested a lean mixture with λ = 1.8 and a compression ratio of 14 seemed possible.
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| Cutaway of the lean-burn unit. The cutaway exhibit features an enlarged model of the ignition chamberIn the foreground is a natural gas quality sensor. Click to enlarge. |
Nevertheless, Volkswagen says, exhaust gas treatment continues to be a technological challenge with lean combustion processes (λ>1) compared to the homogeneous concepts (λ=1) found in the marketplace.
Cold-start procedure with all-gas operation is another focus of research related to monovalent CNG power units.
The 42-month, €23.4-million (US$27-million) GasOn project aims to develop CNG-only mono-fuel engines with improved efficiency and able to comply with post-Euro6 emission targets, the 2020+ CO2 emissions target and new homologation procedures.
GasOn is based on 3 parallel technology paths that lead to a full development of demonstrator vehicles, all based on the integration of the gaseous direct injection system developed in the project, and focusing on direct injection combined with an advanced Variable Valve Actuator VVA system; an advanced boosting system matched with Variable Compression Ratio; and a lean burn and/or charge dilution combustion approach and exhaust gas temperature control.
To complete the investigation of all potential exploitable technologies for CNG engines, an ignition chamber concept—with extended lean burn combustion and diesel-like compression ratio—is being developed (VW’s work), as well as natural gas quality sensor that will determine the fuel characteristics and will enable a predictive engine control parameters optimization.
Partners in the project include CRF, Ford, Renault, VW, AVL, CEA, UPVLC, Continental, CVUT, Delphi, EMPA, ETH, FEV, IFPEN, Pierburg, Polito, PUT, Ricardo, and Schaeffler.
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