b'Automotive & Transportation | Engineer InnovationRunners Prism Laser generatorParticles injectionRotating cylinder Camera Airflow directionFigure 4: Unsteady assembly Figure 5: PIV system mounted on the stationary assemblyfins region modeled as phasic mediaexchanges and to maintain the rest of addresses pressure drop as well as heatthe heat exchanger (aluminum and transfer without the need to modelliquid volumes). Therefore, the actual individual fins which would beliquid core and aluminum part are impractical. Concurrently, testmodeled, while the (air/fins) volumes campaigns have been done to validateare modeled by a phasic porous media, the methodology in terms of heatwhich will allow for the computation of exchanges, temperature and velocitiesthe pressure drops and thermal under steady and unsteady flowexchanges (figure 3).conditions.HTC (W/m^2-K)This methodology was made possible597.7607.6617.4627.3637.1 647.0The studied LCAC (figure 1), is a plate- thanks to the phasic porous mediaFigure 6: Heat transfer coefficient in the LCAC, fin hybrid flow heat exchanger wheremodel in Simcenter STAR-CCM+ whichair sidethe air has a single pass while theis able to resolve the energy equation liquid has two-passes. The global flowin the solid part of the porous media.creates a counter flow heat exchanger, while each pass of liquid forms aWith such a phasic porous media, the crossflow heat exchanger. heat exchanges are possible between both phases (air and aluminum) inside On the air side, the fins are louveredeach cell.This modeling needs two (figure 2).additional input parameters: the interaction area density that represents A fine detail model for heat flux andthe exchange surface of one cubic fluid flow meter of porous medium; and the heat The meshing of the louvered fins for thetransfer coefficient (HTC) that can be entire LCAC is impossible because itobtained empirically or with a detailed would involve more than two billionsimulation.cells. However, we need to accurately represent the heat exchanger geometryFor HTC, the latter method has been and the temperature distribution,chosen: getting the heat transfer whether the air flow is uniformlycoefficient by modeling an elementary distributed at the inlet or not. volume The goal was to describe the HTC in function of the geometry and The aim is to keep the model asthe flow, by finding a relationship representative as possible by finding abetween the Nusselt, Reynolds and specific treatment to the air/finsPrandtl numbers: HTC=f(Re,Pr).T_air at inletHeat exchangesAir temperature at outlet141C [kW][C] Tests bench 8.94 45.6CFD model 8.95 45.4Figure 7: Heat exchanges in stationary case67'