Online Archive of University of Virginia Scholarship
Exploration of Micro/Nano Scale Heat Transfer for Microchannels and Isothermal Compression and Expansion6 views
Author
Jennings, Darryl, Mechanical and Aerospace Engineering - School of Engineering and Applied Science, University of Virginia
Advisors
Loth, Eric, EN-Mech & Aero Engr Dept, University of Virginia
Abstract
This work explores enhancing cooling via optimization of micro channel heat sinks and implementation of hydrophobic nanostructures. The goal of this segment is to present an analytical model of nanostructures and study the effects of their geometry on the performance of micro channels. The pressure drop experienced by micro channels is of interest as it presents a limit on forced convection heat transfer. This work will demonstrate how the presence of nanostructures primarily affects pressure drop as well as other cooling flow characteristics. Additional work in the impact of microchannel cross-sectional geometry and friction factor formulation is provided as well. Multiple transient analyses were performed in ANSYS FLUENT to ascertain performance characteristics of microchannels without the presence of hydrophobic nanostructures. The results were compared to the analytical model developed in this study.
This work also expands on previous spray-based studies by considering higher pressure ratios and full-scale conditions consistent with a direct-drive offshore wind turbine for turbine integrated compressed air energy storage. The spray-based numerical model is validated with experiments and is then used to assess the performance of a Megawatt-scale compression/expansion system for various droplet mass loadings and droplet diameters. The results suggest a range of system parameters that can yield isothermal roundtrip efficiencies greater than 90%. Additionally, a specific offshore platform, a Monopile, is examined for integration of a near isothermal compressor/expander. The feasibility of this design is compared to the limiting constraints of current CAES systems. However, further work is needed to investigate the impact of multidimensional flow effects, non-linear piston velocities, the influence of droplet collisions, and the differences between compression and expansion efficiencies.
Jennings, Darryl. Exploration of Micro/Nano Scale Heat Transfer for Microchannels and Isothermal Compression and Expansion. University of Virginia, Mechanical and Aerospace Engineering - School of Engineering and Applied Science, PHD (Doctor of Philosophy), 2026-07-29, https://doi.org/10.18130/nqpg-5m97.
