Validation and sensitivity analysis of an in-flow water condensation model for 3D-CFD simulations of humid air streams mixing

Abstract

The mixing of gaseous streams at different humidity and temperature conditions may generate bulk condensation, which is a particular thermodynamic process that usually implies a great computational effort. A model that provides in-flow condensation predictions without heavily impacting on the simulation time becomes a potential tool for studying situations where the presence of water droplets is a problem. For instance, in a Long-Route Exhaust Gas Recirculation (LR-EGR) system, intake fresh air is mixed with humid and hot exhaust gases, generating water droplets that may impact on the turbo-compressor impeller and produce harmful erosion. Serrano et al. [1] developed a condensation submodel for such purpose. In this work, the 3D CFD methodology is analyzed by means of sensitivity studies on the numerical setup and intake throttle valve angle. Validation of the model is addressed by means of measurements in a fully instrumented continuous flow turbocharger test bench, obtaining quantitative and qualitative agreement. Particularly, a consistent correlation was found between predicted condensation rate and the impeller damage for seven LR-EGR configurations. Moreover, the T-joint geometry is noticed to have a great impact on condensation generation, thus showing the potential of such a 3D model for improving the LR-EGR design.