5:00 PM - ES13.03.04
Thermomechanical Design Optimization for Low Metal Footprint in Hybrid Metal-Polymer Heat Exchanger
Manjunath C. Rajagopal1,Ho Chan Cheng1,Yuquan Meng1,Gowtham Kuntumalla1,Timothy Man1,Gabriele Baiamonte1,Sreenath Sundar1,Hanyang Zhao1,Srinivasa Salapaka1,Placid Ferriera1,Chenhui Shao1,Nenad Miljkovic1,Sanjiv Sinha1
University of Illinois at Urbana-Champaign1
Material and maintenance costs of metal-based heat exchangers surpass profits in waste heat recovery (WHR) from ultra-low temperature (<100C) sources . A low-cost alternative like polymer pipes suffer from poor thermal conductivity (~0.2 W/mK), and a low overall heat transfer coefficient. Polymers’ thermal conductivity have previously been enhanced through systematic molecular alignment by stretching , chemical vapor deposition of extended polymers , surface grating , etc. However, these approaches suffer from scalability issues for WHR heat exchangers in terms of cost , and thermomechanical considerations . In this work, we propose novel hybrid metal-polymer heat exchangers that are made from polymer-copper strips. Through finite element method (FEM) simulations, we first optimize the placement of copper around polymer strips to enhance the transverse thermal conductivity of the strips. The copper cladded polymer strips are wound helically in a roll-to-roll system to form the pipes for a heat exchanger. We then optimize the design of helically wound pipes to reduce thermomechanical strains to < 0.2 % at 100C and 40 psi working conditions. At 25 % volume fraction of copper in the pipe, we predict up to 20 % enhancement in overall heat transfer from a base polymer with a thermal conductivity of 0.2 W/mK. We also compare and contrast the thermomechanical performance of the optimized metal-polymer strips to random metal matrix composites. Finally, we experimentally verify the thermal conductivity of the optimized strips through bulk thermal conductivity and thermal interface resistance measurement setup. By systematically improving the design through FEM and experimental measurements, we provide an optimized design of hybrid metal-polymer pipes that provides a low metal footprint and cost-effective means for harvesting waste heat from ultra-low temperature sources.
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