Assuming cylinder pressure data is available what is the best way to model NOx?
Please look for the following paper
Tesfa, B., Mishra, R., Gu, F. and Ball, A. (2014) ‘NOx Emission Prediction Based on Measurement of in-Cylinder Pressure for CI Engine Running with Diesel and Biodiesel’ International Journal of Automotive Engineering and Technologies , 3 (2). ISSN 2146-906
Rolf Egnell, From the Lund University of Technology did a lot of work in this area, you may want to look at his work. Some references are "Combustion Diagnosis by Means of Multizone Heat Release Analysis and NO Calculation", SAE paper 981424, "A Simple Approach to Studying the Relation Between Fuel Rate, Heat Release Rate and NO Formation, SAE paper 1999-01-3548. "The Influence of EGR on Heat Release Rate and NO Formation in a DI Diesel Engine", SAE Paper 2000-01-1807, "A Theoretical Study of the Potential of NOx Reduction by Fuel Rate Shaping in a DI Diesel Engine", SAE paper 2000-01-2935, and "Comparison of Heat Release and NOx Formation in a DI Diesel Engine Running on DME and Diesel Fuel", SAE paper 2001-01-0651.
If you have cylinder pressure data on a crank angle basis, heat release calculations are quite simple from a basic first law analysis.
It is the best to use KIVA III combined with chemical kinetics to simulate NOx production in engines.
Assuming cylinder pressure to calculate NOx is almost impossible. Even if you obtain the result, which will be very rough. Usually NOx calculation needs chemical kinetics.
He did not say to assume pressure data, he said, "assuming" it is available, that means he measures it. Using that, and some of Egnell's methods, one can calculate the heat release, a simple calculation, and get the local temperature of the flame (which is close the the stoichiometric, equilibrium flame temperature in a diffusion flame - see Egnell's results) and then with a fairly simple kinetic model estimate NOx. Engell's methods could also be used for an estimate of flame area, which you would also need to know.
KIVA is fine for detailed analysis, but I still don't think it is suitable for real time analysis. We have developed real time models for engine performance (MVEM's) for use in control systems, and KIVA is much too demanding in terms of computer resources to be used there.
A lot of modelling work is done by RWTH Aachen. They are creating model based control of partly homogenized combustion in diesel engines, but their modelling is focused on exhaust emissions, such as NOx. Here the site:http://www.sfb686.rwth-aachen.de/index.php?id=1173&L=1&cHash=aa67e02eb922b634562869fb9b2aa460
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