Talking shop

Professor Evelyn Wang

Jordan Lewis asks MechE Professor Evelyn Wang about the Device Research Laboratory and the thrills and challenges of research at the nanoscale.

Evelyn Wang with Microscope Professor Evelyn Wang, the Esther and Harold E. Edgerton Career Development Assistant Professor in Mechanical Engineering, joined the MechE faculty in 2007. She was honored with the DARPA Young Faculty Award in 2008. She earned her BS from MIT in 2000 and an MS and PhD from Stanford University in 2001 and 2006. Her recent collaboration with Professor John Brisson and their DARPA project team earned a Best Paper Award at the IEEE-ASME ITherm Conference.

Your research includes solar energy, desalination, and thermal management. Is there a common thread?

Yes, they involve heat and mass transport at the micro and nanoscales. In the Device Research Laboratory, we’re trying to control these processes for a wide range of mechanical engineering applications. The nanoengineered surfaces and devices we are developing can improve membranes for desalination in one project and control the cooling of solar cell arrays in another.

Cooling a solar cell array must present very different challenges from, say, cooling an automobile?

Managing the heat generated in an automobile engine versus a nuclear reactor is far different because of the scale. We have learned that to develop compact, high performance cooling devices, the dominating physics—the physics that drive the flow of fluids during phase change, for example— are not as easily defined or predictable when you work at the nanoscale.

In the lab, when we use water as a cooling medium, we find that the surface tension of water plays a much bigger role in the flow than what you would find in a larger scale system. We are only starting to understand how our designs will perform at the nanoscale, and that’s what makes for exciting research.

droplet of water on micro pillars

ASYMMETRIC WETTING
Nanostructured surfaces for controlled wetting and transport from the research of Professor Evelyn Wang and her group.

How are you applying your research to the desalination process?

We are studying zeolite crystals to see if they can be incorporated into water filtration membranes. Zeolites, which have pores that are smaller than a billionth of a meter, could offer the ideal geometry and material properties for separating salt from water, while reducing the energy required for the process. Learning exactly how this separation process occurs is the first step—but utilizing zeolites in a large-scale desalination process is our ultimate goal.

What role does your nanoscale research have in your teaching?

In the undergraduate thermal fluids engineering courses (2.005 and 2.006), we are often working with problems that focus on learning the fundamentals of heat transfer, fluid flow, and thermodynamics. Yet in my research, we find that scaling a process down to the nanoscale tends to introduce multiple layers of questions that complicate the answers. This semester, I’m offering an advanced undergraduate course in heat transfer (2.51) in which students can start to tackle some of the nanoscale problems that we face in the lab. And we can still apply some of the lessons learned from 2.005 and 2.006. It will be fun.meche logo

MechE Connects editor Jordan Lewis is a communications specialist in the Department of Mechanical Engineering.

Learn more: drl.mit.edu/