04/03/2024
By Danielle Fretwell

The Francis College of Engineering, Department of Mechanical Engineering, invites you to attend a Master's Thesis defense by Joshua Landis on: Measurement and mitigation of NOx emissions from the combustion of hydrogen and ammonia

Candidate Name: Joshua Landis
Degree: Master’s
Defense Date: Wednesday, April 10 2024
Time: 1 - 3 p.m.
Location: ETIC 445

Committee:

  • Advisor: Prof. John Hunter Mack, Associate Professor, Mechanical & Industrial Engineering, UMass Lowell
  • Prof. Juan Pablo Trelles, Professor, Mechanical and Industrial Engineering, UMass Lowell
  • Prof. Dimitris Assanis, Assistant Professor, Mechanical Engineering, Stony Brook University

Brief Abstract:
Given the significant environmental concerns associated with emissions from energy systems, effective mitigation strategies are crucial to a sustainable future. This is particularly relevant considering the movement towards low-carbon fuels such as
hydrogen (H2) and ammonia ( NH3) due to their inherent lack of CO2 emissions and the presence of fuel-bound nitrogen. Of particular importance is the production of oxides of nitrogen, including NO, NO2, and N2O, which contribute to global warming, acid rain, and tropospheric/stratospheric ozone formation. While NOx emissions is widely monitored in combustion systems, N2O is also of interest due to its large global warming potential (GWP). This thesis investigates the use of H2 and NH3 from three distinct angles: (i) the synthesis of NH3 via Dielectric Barrier Discharge (DBD) plasma technology; (ii) the emissions produced by (H2)-(NH3) blends during combustion; and, (iii) the destruction of oxides of nitrogen, again utilizing a DBD plasma reactor. In each study, Fourier-transform infrared spectroscopy (FTIR) is employed as an effective technique for quantitatively analyzing the concentration of the species of interest. The infrared absorption of these greenhouse gasses are very predictable as they occur at discreet frequencies. The spectroscopic nature of the FTIR lends its ability to resolve interfering absorption bands between species that common non-dispersive instruments lack. In constant volume combustion chamber (CVCC) experiments, NOx production was compared across a wide range of H2-NH3 blends and equivalence ratios. The results provided insight into the complex dynamics of NOx formation and motivated mitigation approaches such as staged combustion, where operation envelopes strategically target regimes that minimize emissions of oxides of nitrogen. With respect to ammonia synthesis, design optimization of the DBD reactor, such as adjusting reactor porosity and pore size, led to significant improvements in NH3 production], suggesting further enhancement opportunities through catalyst integration and/or gas recirculation techniques. Lastly, the DBD plasma approach was shown to be an effective route to NOx abatement with reductions of 93-100% across various flow rates and power inputs. The promising outcomes from the DBD plasma research highlight its applicability in scenarios requiring thorough NOx control and remote NH3 synthesis to demonstrate the importance of continued development in plasma-assisted technologies for environmental remediation. Ultimately, the findings emphasize the need for combustion systems to be designed with NOx emissions in mind as we transition towards a low-carbon future.