DOE OSTI2019
In the United States, over 50% of the unrecovered e nergy from industrial processes is in the form of low- grade heat (<220°C). Materials and maintenance co sts of common heat exchangers are typically too hig h to justify their usage. Polymers, though more afford able, are usually unsuitable for HX applications due t o their low thermal conductivity (~0.2 W/mK). Here, we show that metal-polymer hybrids may be attractiv e from both performance and cost perspectives. The use of polymers further increases the resistance to c orrosion by sulfuric and carbonic acids often present in flue gases. An ongoing work explores different co nfigurations of layered polyimide-copper macroscale hybrids for heat exchanger applications using numeri cal simulations. This paper explores a manufacturing pathway for producing such layered hybrid tubes tha t involves directly rolling and bonding tapes made of polymer and copper foil into tubes. A critical problem in the fabrication process is the bonding of metal and polymers. We explore approaches involving adhesiv es (epoxy, acrylic and silicone) for metal/polymer inte rfaces and direct welding (ultrasonic) for metal/metal interfaces that can be integrated into the manufacturi ng process. We report characterizations of the therm omechanical properties of these joining processes. T his work paves the way for realizing cost-effective m anufacturing of heat exchangers for low grade waste heat recovery.