Real-time Measurement of Oxides of Nitrogen: from Heavy-Duty Diesel Engines

Real-time Measurement of Oxides of Nitrogen from HeavyDuty Diesel Engines New emissions regulations and performance requirements imposed on modern diesel engines encourage the development of improved tools for emissions measurements. This study investigated one of the improved tools for NOx emissions measurement. Objectives of this thesis included measurement, comparison and prediction of NOx emissions from heavy-duty diesel engines using two different NOx analyzers. Steady state and transient tests were conducted on six heavy-duty diesel engines in the WVU Engine and Emissions Research Center (EERC). NOx emissions were measured using a conventional Rosemount NOx analyzer and a Cambustion fast response NOx analyzer. The Rosemount analyzer sampled dilute emissions whereas the fast NOx analyzer was capable of sampling both raw and dilute NOx emissions. Test data obtained from both the analyzers were compared and contrasted. It was observed that there occurred a time shift and dispersion in the measured NOx emissions due to the delay and diffusion effects of the sampling train and the difference in response time of each of the analyzers. A difference of about 8-10% was observed between the measured values of NOx emissions from the two analyzers. Instantaneous emissions data obtained from the fast NOx analyzer were used to create emissions inventory tables for further analysis. These data were used to deduce power-based fast NOx emissions prediction models, which could predict instantaneous NOx emissions for different engines and cycles within an error range of 5-13%. An attempt was also made to derive algebraic backward transformation equations for predicting the instantaneous engine out emissions (raw) from the dispersed (dilute) emissions.