A cross-country collaboration between companies and researchers in British Columbia and Ontario should enable the high-tech capabilities of graphite to withstand the brutal economics of building heat exchangers. An innovative method of rolling this material through press-like drums promises to introduce an entirely new cost structure to all kinds of thermal management systems.
A novel method of rolling graphite expands its industrial uses. Photo by: Peyman Taheri
Systems designed to dissipate excess heat come in a variety of shapes and sizes, from the coils on the back of a kitchen refrigerator to the finely honed bipolar plates found in fuel cells. For example, while the thermal conductivity of aluminum or copper ranges between 100 and 300 watts per metre-kelvin, graphite is capable of delivering 700 watts per metre-kelvin.
What usually keeps graphite out of such installations is the need to stabilize its flake-like internal structure with resins that need a great deal of machining, which adds to the cost. This challenge is being tackled by Majid Bahrami, an associate professor in Simon Fraser University’s School of Mechatronic Systems Engineering. Bahrami has been working with Mission, BC-based Terrell Energy Systems on a means of producing stable graphite sheets by binding and embossing them through the equivalent of a paper printing press. “It comes out like cardboard but very thin,” he says. “We print these sheets with particular features on them, such as channels. Then we just stack them up on top of each other — hot fluid, cold fluid, you get a heat exchanger that doesn’t corrode or oxidize.”
This technology is coming closer to commercialization with $700,000 in funding from the Natural Sciences and Engineering Research Council’s College and Community Innovation program. Bahrami is now looking forward to refining this graphite production technique at the Centre for Advanced Manufacturing and Design Technologies, which is operated by Sheridan College in Brampton, Ont. “There are some challenges, but the potential is huge,” says Bahrami. “If you look at the issues with heat exchangers in the automotive industry, most of them are related to corrosion/fouling and weight/cost, which can all be addressed with this graphite technology.”