Numerical Investigations of Thermal-Fluid Phenomena Across Emerging Energy Systems

Author

• Nicholas C. Lopes, Embry-Riddle Aeronautical UniversityFollow

ORCID Number

0009-0007-8859-2280

Date of Award

Spring 2026

Embargo Period

5-1-2036

Access Type

Dissertation - Open Access

Degree Name

Doctor of Philosophy in Mechanical Engineering

Department

Mechanical Engineering

Committee Chair

Sandra K.S. Boetcher

Committee Chair Email

boetches@erau.edu

First Committee Member

Mark Ricklick

First Committee Member Email

ridlickm@erau.edu

Second Committee Member

Rafael Rodriguez

Second Committee Member Email

rodri7d6@erau.edu

Third Committee Member

Leitao Chen

Third Committee Member Email

chenl12@erau.edu

Fourth Committee Member

Yang Chao

Fourth Committee Member Email

ychao@csuchico.edu

College Dean

James W. Gregory

Abstract

This dissertation presents numerical investigations of thermal–fluid phenomena across different energy systems, with emphasis on predictive modeling and heat transfer behavior under extreme or highly variable conditions. The first portion of the work focuses on supercritical carbon dioxide (sCO₂), a working fluid of increasing importance in advanced power and refrigeration cycles. A comprehensive historical review of sCO₂ heat transfer correlations is conducted to evaluate their evolution and limitations near the critical region, followed by the development and assessment of artificial neural networks for predicting cooling heat transfer in comparison with the conventional correlation-based methods. Additional studies examine the influence of inlet boundary conditions in tube-in-tube heat exchangers and the combined effects of geometry and buoyancy in non-circular ducts, providing insight into mechanisms governing enhancement and deterioration of heat transfer in near-critical flows. The dissertation then extends to gas turbine systems through the design and computational evaluation of a novel combustor effusion cooling configuration, demonstrating how geometric modifications influence film cooling effectiveness and liner thermal loading. Finally, high-fidelity simulations of bio-based phase change material capsules integrated into residential heat pump water heaters are performed to assess heat transfer enhancement, discharge behavior, and overall system performance.

Scholarly Commons Citation

Lopes, Nicholas C., "Numerical Investigations of Thermal-Fluid Phenomena Across Emerging Energy Systems" (2026). Doctoral Dissertations and Master's Theses. 960.
https://commons.erau.edu/edt/960