08/05/2025
By Danielle Fretwell

The Francis College of Engineering, Department of Energy Engineering - Renewable, invites you to attend a Doctoral Dissertation Proposal defense by Yicheng Zhang on: "Direct Nitrogen Oxides Abatement via Atmospheric Pressure Conventional and Membrane Dielectric Barrier Discharge Plasma."

Candidate Name: Yicheng Zhang
Degree: Doctoral
Defense Date: Monday, August 18, 2025
Time: 10 - noon
Location: Perry Hall 415

Committee:

  • Advisor: Juan Pablo Trelles, Professor, Mechanical and Industrial Engineering, University of Massachusetts Lowell
  • Dimitris Assanis, Assistant Professor, Mechanical Engineering, Stony Brook University
  • Noah Van Dam, Assistant Professor, Mechanical and Industrial Engineering, University of Massachusetts Lowell
  • John Hunter Mack, Associate Professor, Mechanical and Industrial Engineering, University of Massachusetts Lowell

Brief Abstract:
The combustion of carbon-free fuels, such as hydrogen–ammonia blends, promising candidates for zero-CO2 long-haul transportation, can result in elevated nitrogen oxides (NOₓ) emissions, particularly under cold-start conditions. Dielectric barrier discharge (DBD) plasma reactors offer a compelling low-temperature, non-catalytic approach for dynamic NOₓ abatement. In this study, we evaluate the performance of conventional DBD and membrane-based DBD (mDBD) reactor configurations for the direct decomposition of NOₓ. Our results demonstrate that both systems can achieve over 90% NOₓ reduction. Notably, under lower power conditions and high flow rates, the mDBD configuration achieves up to 15% higher NOₓ reduction compared to conventional DBD. Species-resolved analysis indicates preferential removal of NO₂ in both configurations, while NO abatement is limited by NO2 back-reactions that regenerate NO. The improved performance of mDBD under low-power, high flow rate conditions is attributed to enhanced micro-discharge activity, driven by radial gas flow that disrupts charge accumulation on the membrane surface, and extended gas residence time through the plasma zone increasing the likelihood of reduction reactions. Future work will evaluate the performance of the DBD and mDBD configurations during the treatment of different simulated exhaust streams, particularly streams with up to 14% oxygen – characteristic of lean burn conditions. Since oxygen and water vapor both exist in exhaust streams and both reportedly inhabits NOₓ abatement efficiency, these tests will help assess reactor robustness under more diverse operating scenarios. Future work will also encompass the development of a non-equilibrium plasma thermo-fluid model to simulate the operation of the DBD and mDBD reactor configurations and unveil their underlying characteristics. This research aims at assessing the potential advantages of integrating a dielectric membrane for distributed gas delivery into DBD reactors for on-demand NOₓ control at low temperatures.