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Miniature Precision Uses EFD.V5 Flow Simulation to Optimize Hydrocarbon Trap
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Miniature Precision Components, Inc., Walworth, Wisconsin, optimized the design of a new hydrocarbon trap by simulating
it with EFD.V5, a design-oriented flow simulation software package. Mark Van de Bogert, Product Design Manager for
Miniature Precision Components, evaluated the performance of 12 different design alternatives in order to minimize
backpressure across the trap while achieving the required level of hydrocarbon absorption.
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“EFD.V5 simulation showing predicted pressure drop and flow velocities through a catalytic converter”
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“EFD.V5 makes it easy and inexpensive for design engineers to perform computational fluid dynamics simulations that
in the past would have required the service of analysts with advanced degrees and software packages that lease for
tens of thousands of dollars per year,” Van de Bogert said.
Miniature Precision Components is a leader in the design and manufacture of injection molded emission control components.
The company saw the need for a cost competitive hydrocarbon trap for a partial zero emission vehicle (PZEV) which is 90%
cleaner than the average new car. A key feature of the PZEV vehicle is a hydrocarbon trap in the air intake that prevents
stray hydrocarbons from migrating out of the engine after shutdown. The hydrocarbon trap presents the inherent design
challenge of requiring the ability to trap nearly all hydrocarbons while avoiding a significant increase in backpressure
for air entering the engine because that would adversely affect fuel efficiency and performance.
“Modeling the design in EFD.V5 was easy,” Van de Bogert said. “I simply called up the software inside CATIA. EFD.V5
automatically distinguished between the solid and empty spaces in our CAD model and meshed the empty regions to prepare
for flow analysis. I added the boundary conditions within CATIA, a mass flow rate upstream and a pressure boundary
condition downstream of the trap. I analyzed various rib configurations and found that a 5 spoke version’s backpressure
was the lowest, but still not low enough.”
Van de Bogert then ran through about a dozen iterations on the 5-spoke design, changing the geometry of the spokes
and the spacing of the carbon elements. The analysis results for each design showed flow rate and direction and pressure
at each point in the trap. “The ability to visualize the flow helped me understand where the restrictions were in each
design and provided insight into how to reduce the backpressure,” Van de Bogert said. “By the end of this process I had
beaten the target for backpressure. We built a rapid prototype of the optimized design and were delighted to discover
that the backpressure of the rapid prototype was within a tenth of an inch of water of the CFD predictions.”
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