Author ORCID Identifier

https://orcid.org/0000-0003-4178-3390

Defense Date

2025

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Mechanical and Nuclear Engineering

First Advisor

Dr. Karla M. Mossi

Second Advisor

Dr. Reza Mohammadi

Third Advisor

Dr. Carlos Castano

Fourth Advisor

Dr. Ernesto Gutierrez-Miravete

Fifth Advisor

Dr. Gokul Vasudevamurthy

Abstract

Global electricity generation still relies heavily on thermal power plants, which consume vast amounts of fuel and emit significant amounts of carbon dioxide. A major but often overlooked source of inefficiency in these plants lies within the rotary regenerative air preheater (RAPH), a critical heat-exchange component where air leakage can exceed 20% in aging units. This leakage increases fuel consumption, parasitic fan power, and CO₂ emissions, while degrading boiler reliability.

This research introduces advanced adaptive sealing systems designed to mitigate these losses by dynamically compensating for rotor eccentricity, thermal distortion, and wear under harsh operating conditions. Brush seals, composed of thousands of flexible filaments, conform to surface irregularities and varying gap sizes, dissipating stress under deformation to minimize drag and wear. Unlike rigid strip seals—which fail to adapt to uneven surfaces and allow leakage at wider gaps—brush seals offer superior abrasion resistance, flex life, and bend recovery. They maintain sealing integrity under high differential pressures and thermal expansion, ensuring consistent performance across operating conditions.

A reverse-engineering methodology using 3D modeling and in-situ rotor mapping enabled custom seal design without OEM drawings. Field deployments across 25 power plants in 12 countries demonstrated leakage reductions from 22% to as low as 4.5%, fan-power savings up to 15%, and annual CO₂ reductions exceeding 10,000 tons per unit. Thermodynamic analysis following ASME PTC 4.3 confirmed heat-rate improvements of 170–280 kJ/kWh and payback periods under six months, achieving carbon-abatement costs below $4 per ton.

Materials engineering investigations addressed corrosion and erosive wear, while predictive-maintenance frameworks incorporating leakage mapping and digital-twin integration enhanced lifecycle reliability. The study concludes with a techno-economic roadmap for scaling the technology to Rothemühle-type air preheaters and future spring-loaded adaptive seals.

Comments

Doctor of Philosophy in Mechanical and Nuclear Engineering

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

11-12-2025

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