Life Cycle Design of Air Intake Manifolds: Phase II: Lower Plenum of the 5.4 L F-250 Air Intake Manifold, Including Recycling Scenarios
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 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%). The vibration welded composite also produced the least life cycle solid waste, 4.45 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%) of the solid waste from the aluminum manifold. End-of-life waste accounted for a significant portion (55-59%) 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% to 85% will increase the life cycle energy by 10%. Utilizing available technology for incorporating 30% post consumer nylon into the vibration welded composite manifold would reduce life cycle energy use by 4%. Similar effects for both aluminum and nylon systems were shown in other inventory categories such as CO2, 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% less than the lost core composite, which is 20% less expensive than the sand cast aluminum manifold. Additionally, 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.
This report was submitted in partial fulfillment of Cooperative Agreement number CR822998-01-0 by the National Pollution Prevention Center at the University of Michigan under sponsorship of the U.S. Environmental Protection Agency. This work covers a period from April 14, 1997 to April 30, 1999; the life cycle design analysis was conducted between May 12, 1997 to August 1, 1997.