TOWARDS VALIDATED CATALYTIC REACTOR MODELS
Licentiate thesis, 2020
This thesis presents a mathematical model, a so-called single-channel 1+1D reactor model, that describes the reactions that occur inside a diesel oxidation catalyst (DOC) - along with the heat and mass transport. Moreover, the purpose was to improve an already existing model using relevant experiments such as kinetic experiments in a synthetic catalyst activity test (SCAT) bench, gravimetric analysis (GA), temperature programmed desorption (TPD) as well as scanning electron microscopy (SEM). These experiments enabled better inputs for the modelling framework. Furthermore, emphasis has been put towards investigating boundary conditions for the experimental setup. The radial mixing in a SCAT bench was investigated using pair of cleverly designed DOCs. The investigation showed that there was a concentration maldistribution across the catalyst inlet and the problem was solved using a 3D printed -alumina mixer.
The original 1+1D model relies on some simplifications which are rarely fulfilled. The model assumes that the catalytic washcoat forms a uniform slab - an assumption which may lead to incorrectly estimated light-off temperatures. This limitation of the 1+1D model was circumvented through the use of a sectionalizing principle, where the washcoat was divided into multiple segments which were simulated independently. Different experiments allowed for estimation of local properties - such as external mass transfer coefficient, washcoat porosity and thickness. The new model showed increased NO conversion at elevated temperatures compared to the original model.
By improving these single-channel models, EATS modelling in general can become more predictive - leading the way to emission-free transportation.
scanning electron microscope
Exhaust aftertreatment modelling
synthetic catalyst activity test
diesel oxidation catalyst
Chalmers, Mechanics and Maritime Sciences, Combustion and Propulsion Systems, Engines and Propulsion Systems
Use of 3D-printed mixers in laboratory reactor design for modelling of catalytic converters
Efficient Experimental Approach to Evaluate Mass Transfer Limitations for Monolithic DOCs
Topics in Catalysis,; Vol. 62(2019)p. 391-396
Emission control by validated catalytic reactor modelling
Swedish Energy Agency, 2017-01-01 -- 2020-12-31.
Areas of Advance
Chalmers University of Technology
Opponent: Ronnie Andersson