A Combined 0D-3D Numerical Approach for the Performance Prediction of Vehicles' Heat Exchangers Under Actual Operating Conditions

The paper focuses on the development of a predictive numerical tool for the performance assessment of air-cooled cross-flow heat exchangers for vehicle application. First, a CFD approach for the simulation of vehicles' radiators under actual operating conditions is proposed. The numerical analysis accounts both for the thermo-fluid dynamics behavior of each section of the heat exchanger and for the flow characteristics of the adopted fan. The full-scale geometry of the fan is included in the simulation as well as the casing and the real rotational speed. The CFD results are used to correlate the flow distribution across the different radiator's sections and the actual working conditions of both the heat exchanger and the fan operation. Following this methodology, a generic radiator was divided in two different sub-domain types (internal/boundary), and for each one the Wall Heat Transfer Coefficient and the pressure drop 2D maps are determined on the basis of preliminary CFD simulations as functions of fluid velocity and temperature. These elements became the elementary blocks to be used by a custommade algorithm to characterize exchangers of any size. The algorithm was extended to develop a fully featured PC software to calculate the performance of multiple sections exchangers.