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UREA-WATER DROPLET PHASE CHANGE AND REACTION MODELLING: MULTI-COMPONENT EVAPORATION APPROACH

Viraj Suresh Shirodkar
Frontiers in Heat and Mass Transfer (FHMT) 7 - 5 (2016)


Abstract


Urea-water solution droplet evaporation is modelled using multi-component droplet evaporation approach. The heat and mass transfer process of a multi-component droplet is implemented in Langrangian frame through a custom code in ANSYS-Fluent R15. The evaporation process is defined by convection-diffusion controlled Stefan flow model. Rapid Mixing model assumption is used for the droplet internal physics. The code is tested on a single multi-component droplet to check the predicted rates of evaporation at different ambient temperatures. The approach is used to model the injection of urea-water solution spray in a duct carrying hot air to to predict the urea to ammonia conversion efficiency. Thermolysis reaction of the evaporated urea vapors and the hydrolysis of the byproduct iso-cyanic acid are solved as volumetric reactions in Eulerian frame using laminar finite rate approach. The simulation results are compared with the experimental data and the numerical results of direct decomposition approach based on droplet surface reactions available in the literature.


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DOI: http://dx.doi.org/10.5098/hmt.7.5

ISSN: 2151-8629