Thermal and Manufacturing Design of Polymer Composite Heat Exchangers

Abstract

Polymer heat exchangers, using thermally-enhanced composites, constitute a "disruptive" thermal technology that can lead to significant freshwater and energy savings. The widespread use of seawater as a coolant can be made possible by the favorable qualities of thermally-enhanced polymer composites: good corrosion resistance, higher thermal conductivities, higher strengths, low embodied energy and good manufacturability. Polymer composites can bridge the gap between unfilled polymers and corrosion-resistant metals, and can be applied to a variety of heat exchanger applications. However, thermally enhanced polymer composites behave differently from more conventional polymers during the molding process. The desired thin walled large structures are expected to pose challenges during the molding process. This dissertation presents a design methodology that integrates thermo-fluid considerations and manufacturing issues into a single design tool for thermally enhanced polymer heat exchangers. The methodology shows that the choice of optimum designs is restricted by moldability considerations. Additionally, additive manufacturing has the potential to be a transformative manufacturing process, in which complex geometries are built layer-by-layer, which could allow for production and assembly of heat exchangers in a single step. In this dissertation, an air-to-water polymer heat exchanger was made by fused deposition modeling and tested for the first time. This dissertation also introduces a novel heat exchanger geometry that can favorably exploit the intrinsic thermal anisotropy of filled polymers. A laboratory-scale air-to-water polymer composite heat exchanger was made by injection molding. Its performance was verified empirically, and modeled with numerical and analytical tools.