Diesel Engines in Waste Heat Recovery
Stephen Lynch, an assistant professor of mechanical engineering at Penn State University, focuses on heat transfer engineering. His work on heat exchangers led to a collaboration with Volvo to improve heat exchangers for diesel trucks using additive manufacturing.
Project Background
During his team’s research at Penn State, they explored creating a heat exchanger with cross-flow air direction. While initial prototypes faced challenges with wall thicknesses and supply pressures, the project demonstrated the potential of additive manufacturing to produce small, intricate features comparable to conventional heat exchanger components.
Collaboration with Volvo
Volvo presented a design challenge, prompting Lynch’s team to propose the study “Optimized Diesel Engine, Exhaust Waste Heat Recovery Components Via Additive Manufacturing.” The goal was to address fuel efficiency losses in diesel trucks, where over 60% of energy is lost as waste heat in the exhaust. The team aimed to recover this energy for applications like refrigeration in trucks.
For the Volvo project, the team initially experimented with aluminum before settling on stainless steel due to its durability. Additive manufacturing allowed them to explore high-temperature alloys and other materials at a similar cost.
Research and Development
In the first month of collaboration, the team aligned their goals with Volvo’s technical monitor, modeling their work on an existing waste heat recovery system. They used computational fluid dynamics (CFD) to design and evaluate novel shapes for the heat exchanger’s fin geometry.
After designing up to 20 different fin shapes, the team received 3D-printed parts from a vendor. Testing is underway to validate the accuracy of their computational models. Early results show promise: the new designs achieve 90–95% of the required heat transfer while reducing pressure drop by about half. This balance of high heat transfer and low pressure drop could significantly improve diesel truck efficiency.