Contact: Becky Rische (512) 471-7272
Mary Lenz (512) 471-3151
Date: April 16, 2001
UT Austin graduate student patents process for saving diesel engine fuel
AUSTIN, Texas -- Dimitrios Dardalis, a mechanical engineering graduate student at The University of Texas at Austin, has patented a design that holds promise for dramatic fuel savings in heavy duty diesel engines of the future.
His Rotating Liner Engine (RLE) is not yet in production. But Ph.D. candidate Dardalis predicts his concept ultimately could result in fuel savings of 4.5 percent to 5.5 percent for engines powering today's 18-wheel rigs.
"That may seem like a small number, but it's actually huge," said Dr. Ronald Matthews, professor of mechanical engineering and head of UT Austin's Engines Research Program. Matthews said diesel engines consume vast quantities of fuel to begin with, so any gains in fuel efficiency quickly result in cost savings. And he explained that the fuel economy benefit rises to as much as 27 percent at idle -- a significant figure because cross-country truckers often leave their engines idling all night.
A UT Austin economic analysis looked at the potential benefit for a truck driven 120,000 miles per year that averages 6.5 miles per gallon of fuel at a cost of $1.40 per gallon. It showed that Dardalis' design could yield annual fuel savings of up to $2,000 per truck per year -- a major incentive for companies with fleets of trucks.
Dardalis said his rotating liner technology can be used on any type of diesel engine, and that all engines using the technology will last longer and require less maintenance. He said the technology could become even more important as the number of trucks on U.S. highways increases, driven by NAFTA, and as new Environmental Protection Agency emissions standards for heavy-duty diesel trucks are phased in.
"Some additional capital cost may not be so painful if you get these payoffs," he said.
Dardalis, 30, is an entrepreneurial thinker who went through the complicated, costly patent process on his own nickel. He received early support for his project from an $89,000 State of Texas Advanced Research Program grant.
Dardalis' design employs rotating liners: the metal cylinders in which an engine's pistons move up and down. Typically, heavy-duty diesel engines have six fixed cylinders tightly pressed into precast cavities within the engine block. A lubricated piston ring moving up and down inside each cylinder generates considerable friction.
This is especially true as a piston ring approaches zero-velocity near the top of its cycle -- a point where lubrication vanishes while the cylinder gas pressure is very high. Eventually, friction wears out the cylinder wall.
Dardalis developed a three-dimensional model, which shows a constant, evenly distributed lubrication film between the piston and inner cylinder wall will occur if the cylinders themselves are rotated throughout the entire cycle. Friction and its attendant wear are both drastically reduced as fuel efficiency rises. Harmful emissions also decrease.
"I got the idea from a design the British used for their World War II combat aircraft," Dardalis said. "I first read about it as a kid, in a technical encyclopedia my parents bought me."
The British aircraft engine model employed rotating liners strictly as a space-saving strategy, to decrease drag on the planes. But it reaped unexpected side benefits in friction reduction, decreasing cylinder wear rate by 10 times the normal rate.
When he began his own work several years ago, Dardalis recognized the value of incorporating the rotational feature into a diesel engine that would reduce fuel consumption.
The success of the rotating liner engine hinges on the "face seal" between the rotating liner and the stationary cylinder head. Coming up with both ideal specifications and the best materials for the high-precision seal is a formidable challenge, Dardalis explained. His current prototype is made from a steel alloy, but he is continuing to test new materials.
Dardalis' next step will be working with John Crane Packing Company, an international face seal technology producer with ultra-high precision manufacturing capabilities, to perfect the prototype. Chicago-based Crane, an international face seal technology manufacturer, has lent its support by providing expert consultation at a minimal cost.
Dardalis recently set up a corporation to perfect, test and ultimately commercialize the core technology worldwide. A team of business and engineering experts with startup experience already is on board to provide strong technical support for its future customers. Dardalis, with his attorney's guidance, was able to do much of the work on the patent application himself, reducing the cost from $10,000 to a little over $2,000. "I got a very cheap deal, because the patent lawyer was willing to work with me," he said. Dardalis holds two prior applications: one pending and one already issued that is held in conjunction with Southwest Research Institute.
For more information, contact Dr. Ron Matthews, director of UT Austin's Engines Research Program, at (512) 471-3108, Dimitrios Dardalis at (512) 471-7025 or Becky Rische at (512) 471-7272.
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