Metal addictively manufactured high T&P microchannel heat exchangers

High efficiency power cycles need to operate at higher turbine inlet temperatures. One such promising cycle, the supercritical carbon dioxide cycle, operates at pressures in excess of 250 bar and temperatures as high as 700-1000 °C at the turbine inlet. Heat Exchangers (HX) account for 40-50% of the total cost of the power cycle and have to withstand thermal stress, creep and fatigue, and in some cases work in a corrosive environment. There is no HX in the market that can meet the needed temperature, pressure, lifetime and corrosion targets. Traditional manufacturing methods impose several constraints on the design of compact heat exchangers for this application. To solve these challenges, an inter-disciplinary team of researchers from UC Davis WCEC and Carnegie Mellon University (CMU) are investigating novel HX designs using metal Additive Manufacturing (AM).

We aim to design a compact HX while minimizing cost, since the materials and methods used for manufacturing are expensive. Compact designs require co-design of thermal-fluidic and mechanical aspects along with manufacturability using metal AM. Concurrent process-based cost modeling by CMU based on our thermo-fluidic models will allow for HX cost optimization.

We developed correlation-based models to predict the HX performance and carried out a parametric study to find out the best geometry dimensions based on the desired HX thermal load. The HX designs have been studied thermally and mechanically through a series of Computational Fluid Dynamic simulations and Thermal-Mechanical structural analysis to ensure high efficiency and reliable designs. Several AM test parts are being made by our partner at CMU and feedback is being incorporated into the HX designs to enable successful fabrication.

Subscale and eventually full scale HXs will be fabricated by CMU and will be experimentally characterized at UC Davis.