The same plastic as in garbage bags makes an efficient heat exchanger in power plants by creating microchannels.
Credit: Joshua Pearce
The plastic used to make garbage bags also makes a good base for building low-temperature heat exchangers. Joshua Pearce, a researcher at Michigan Technological University, has worked with a collaborative group funded by the Advanced Research Projects Agency-Energy. Pearce's team helped design and make the plastic-based heat exchangers to be used in power plants.
The key is expanded microchannel structures, says Pearce, who is an associate professor of materials science and engineering along with electrical and computing engineering at Michigan Tech. He constructs the exchangers layer by layer with a laser welder -- like in 3-D printing -- and then puffs up the plastic. The resulting Michelin Man-like pattern creates microchannels, which allow air or water to pass through, and that transfers heat from the hot side to the cold side of the exchanger.
"The temperature and pressure requirements for the air cooled condensers on power plants are modest," Pearce says, explaining that allows the team to use polymer heat exchangers to improve efficiency and cut costs. "This is really important as conventional power plants are finding it more and more difficult to compete with the recent price drops in renewable energy sources like solar."
"Now, our work is to try and take these small envelopes that we've made successfully and transfer them to a bigger scale," Pearce says. "Even if one day all central power plants are replaced by more nimble distributed generation, heat exchangers may be in your house or your vehicle made out advanced garbage bags, which can increase the heat recovery and save you money at home."