| dc.description.abstract | This work seeks to improve the current ability to model NOₓ emissions from integral compressor engines that are commonly used in the natural gas industry. This improved understanding will be able to inform the development of future control technologies as the natural gas industry seeks to meet increasingly stringent emissions standards. To this end, a zero-dimensional thermodynamic cycle simulation was developed to predict NOₓ emissions for a large bore, single cylinder, naturally aspirated, 2-stroke, natural gas engine. Excellent agreement was obtained between experimental measurements and simulated predictions of the average exhaust NOₓ concentration.
Once the simulation was validated by experimental data, a sensitivity analysis was conducted to determine the response of NOₓ emissions to changes in three factors: trapped equivalence ratio (TER), burned gas fraction (xb), and stuffing box temperature (SBT). It was found that changes in each factor effected linear changes in the combustion temperatures, which effected linear changes in the rate constant of the first reaction in the extended Zeldovich mechanism, which effected exponential changes in the NOₓ emissions. TER and SBT were shown to be directly related to NOₓ, while xb was shown to be inversely related to NOₓ.
Finally, it was demonstrated that since NOₓ is non-linearly related to in-cylinder pressure, an average cycle in terms of pressure is not necessarily an average cycle in terms of NOₓ emissions. This fact underlines a need for future NOₓ modeling efforts to account for cycle-to-cycle variations in engine behavior. | en |
