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.
","abstract_html":"<p>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 (sCO<sub>2</sub>), a working fluid of increasing importance in advanced power and refrigeration cycles. A comprehensive historical review of sCO<sub>2</sub> 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.</p>","abstract_has_math":false,"creators":["Lopes, Nicholas C."],"institution":null,"degree_name":"Doctor of Philosophy in Mechanical Engineering","degree_level":"Dissertation - Open Access","degree_discipline":"Mechanical Engineering","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2026,"date_issued":"2026-04-01T07:00:00Z","date_published":"2026-04-01T07:00:00Z","updated_at":"2026-07-27T19:26:22Z","subjects":["supercritical carbon dioxide; combustor cooling; thermal energy storage; computational fluid dynamics","Aerodynamics and Fluid Mechanics","Energy Systems","Heat Transfer, Combustion"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://commons.erau.edu/edt/960","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Lopes, Nicholas C."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2036-05-01T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Mechanical Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation - Open Access"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Doctor of Philosophy in Mechanical Engineering"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["supercritical carbon dioxide; combustor cooling; thermal energy storage; computational fluid dynamics","Aerodynamics and Fluid Mechanics","Energy Systems","Heat Transfer, Combustion"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://commons.erau.edu/edt/960"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["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.
"]},{"key":"dc:title","label":"Title","values":["Numerical Investigations of Thermal-Fluid Phenomena Across Emerging Energy Systems"]}]}],"canonical_facts":{"dc:creator":["Lopes, Nicholas C."],"dc:date.available":["2036-05-01T07:00:00Z"],"dc:description.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.
"],"dc:identifier":["https://commons.erau.edu/edt/960"],"dc:subject":["supercritical carbon dioxide; combustor cooling; thermal energy storage; computational fluid dynamics","Aerodynamics and Fluid Mechanics","Energy Systems","Heat Transfer, Combustion"],"dc:title":["Numerical Investigations of Thermal-Fluid Phenomena Across Emerging Energy Systems"],"thesis:degree_discipline":["Mechanical Engineering"],"thesis:degree_level":["Dissertation - Open Access"],"thesis:degree_name":["Doctor of Philosophy in Mechanical Engineering"]},"updated_at":"2026-07-27T19:26:22Z"}