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  Life Cycle Design of Air Intake Manifolds, Phase II: Lower Plenum of the 5.4 L F-250 Air Intake Manifold, Including Recycling Scenarios (48 pp, 464 KB) (EPA/600/R-01/059)

This life cycle design project was a collaborative effort between the Center for Sustainable Systems (formerly the National Pollution Prevention Center) at the University of Michigan and a cross-functional team at Ford Motor Company. The project team applied the life cycle design methodology to the design analysis of three alternatives for the lower plenum of the air intake manifold for use with a 5.4L F-250 truck engine: a sand-cast aluminum, a lost-core molded nylon composite, and a vibration-welded nylon composite. The design analysis included a life cycle inventory analysis, a life cycle cost analysis, a product performance evaluation, and an environmental regulatory/policy evaluation.

The life cycle inventory indicated that the vibration-welded composite consumed less life cycle energy (1,210 megajoules [MJ]) compared to the lost-core composite (1,330 MJ) and the sand-cast aluminum manifold (2,000 MJ). The manifold contribution to the vehicle fuel consumption dominated the total life cycle energy consumption (71-84 percent). The vibration-welded composite also produced the least life cycle solid waste (4.45 kilograms [kg]) compared to 5.56 kg and 12.68 kg for the lost-core composite and sand-cast aluminum, respectively.

Waste sand from the sand-casting process accounted for a majority (92 percent) of the solid waste from the aluminum manifold. End-of-life waste accounted for a significant portion (55-59 percent) of the total solid waste from the composite manifolds.

Recycling scenarios for aluminum and nylon were investigated. Potential fluctuations in the availability of secondary aluminum would have a significant effect on the life cycle energy use of the intake manifold. A decrease in recycled aluminum content from 100 percent to 85 percent would increase the life cycle energy by 10 percent. Using available technology for incorporating 30 percent post-consumer nylon into the vibration-welded composite manifold would reduce life cycle energy use by 4 percent. Similar effects for both aluminum and nylon systems were shown in other inventory categories such as carbon dioxide, solid waste, and several air and water pollutant emissions.

The life cycle costs were determined for the three alternative manifolds, including the manufacturing costs, customer gasoline costs, and end-of-life management costs. Estimates provided by Ford indicate that the vibration-welded composite is the least expensive alternative to manufacture, costing 64 percent less than the lost-core composite, which is 20 percent less expensive than the sand-cast aluminum manifold. In addition, the cost of gasoline for the aluminum manifold is $7.31 more than for the composite manifolds, over a 150,000-mile vehicle life. The end-of-life management cost for the composite manifolds was $0.25, while the sand-cast aluminum manifold received a $3.38 net credit due to the value of the recycled aluminum.

This project also provided several observations on the barriers to the life cycle design process, including the availability and accessibility of necessary data and institutional barriers such as the need for clear policy guidance.


Kenneth Stone

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