At the recent 12th International MTZ Conference on heavy-duty and off-highway engines (held in Augsburg, Germany), Ricardo (www.ricardo.com) presented some of the latest thinking on the use of lean-burn natural-gas engines (for heavy-duty trucks) capable of meeting Euro VI emission standards (and better).

The company says that, while long-haul heavy-duty trucks are an essential element of the transport mix of modern industrial economies, they are inherently “less amenable to the type of electrification and hybridisation strategies that are already contributing to reduced carbon emissions and potential long-term sustainability for the light-vehicle sector”.

However, the European ‘Heavy-duty Gas Engines integrated into Vehicles’ (HDGAS) project — in which Ricardo is a partner — aims to deliver improved fuel efficiency and reduced greenhouse-gas emissions compared to current diesel-powered truck engines, while also meeting current Euro VI emissions standards.

In its presentation, Ricardo described some of the simulation and development work carried out as part of the HDGAS project to develop the specification of a lean-operating natural-gas heavy-duty engine and after-treatment system, meeting Euro VI emissions standards, while also emitting 13% less CO₂ than an equivalent ‘state of the art’ diesel alternative.

The appropriate combustion characteristics for lean operation were achieved through the development of a unique combustion system incorporating a ‘tumble port architecture’ and direct gas injection, careful management of the air system from an ‘optimised’ turbocharger, variable valve timing with early intake-valve closing and selected use of exhaust gas recirculation.

Ricardo’s Andrew Noble said: “Natural gas provides a compelling alternative to diesel for heavy-duty road transport with high fuel efficiency — and hence low CO₂ emissions.

"Through our work as a partner on the HDGAS project, Ricardo is pleased to be able to address some of the technical challenges to the adoption of natural-gas power in this market sector.

"We look forward to continuing this research with our HDGAS partners to help bring this environmentally attractive technology forward towards commercial application.”