COVER STORY
A CAD render of the Achates OP engine
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A heavy duty diesel truck confi gured with a 10.6L, 3-cylinder diesel
opposed piston engine taking part in a demonstration program funded by the California Air Resources Board.
Participation in the program showed that the OP engine can reduce tailpipe NOx by 90 per cent (from
current US regulations) while reducing fuel consumption (and CO2
emissions)
by more than 10 per cent compared with conventional diesel engines.
eying ‘opposed piston engine’ into the worldwide patent off ice web site generates over 800 results, prompting the
question: why hasn’t the technology been more widely adopted? Clearly there is interest out there. Maybe this is about to change. Two
companies have teamed up to create a two-stroke, six-piston, three-cylinder upright gasoline OP engine. What’s more, it is compression ignition. It‘s a much upgraded second
generation version of an existing Achates unit. Laurence Fromm is Executive Vice President, Business Development at the company. He says, “We learned of historic OP engine designs, which have always been more eff icient than their conventional engine counterparts. We started the company to modernise the design, using modern tools, supercomputers and powerful design and simulation tools, as well as components such as high pressure common rail fuel injectors, engine control units and precision manufacturing. While always more eff icient, no one thought it possible to
make a two-stroke engine meet modern emissions standards. In a two-stroke cycle, gas exchange and combustion is one integrated process – modifi cations to any part of the engine design aff ects everything. When trial and error was the main development process, it was too time consuming and expensive to design for low emissions and retain high eff iciency. What changed – and what sparked the creation of our company – was the development of supercomputers and sophisticated simulation tools, including chemically reactive computation fl uid dynamics. The engine features an open and closed cycle operation so it could be simulated on computers and designs could be evaluated and developed analytically, and only then verifi ed and refi ned experimentally. Even when runs on supercomputers take days to complete, it is still a lot faster and less expensive than designing parts, assembly and testing.” Fromm sees huge environmental
benefi ts. When asked if OP engines lend themselves to alternative fuels particularly well, he’s very enthusiastic:
www.engineerlive.com 7
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