CFD Modeling of Compact Heat Exchangers for I.C. Engine Oil Cooling 2019-24-0179
In the last years, the increase of the specific power of the modern engines has required a parallel improvement of the performances of the cooling system. In this context, also the control of the oil temperature has become an important issue, leading to the introduction of dedicated cooling circuits (air-cooled or liquid-cooled). Among the two, the liquid-cooled solution results in a more compact installation in which the oil-to-liquid heat exchanger is directly mounted on the engine block and integrated in the engine cooling system.
It is clear that, in a liquid-cooled solution, the design of the heat exchanger represents an issue of extreme concern, which requires a compromise between different objectives: high compactness, low pressure drop, high heat-transfer efficiency. In this work, a computational framework for the CFD simulation of compact oil-to-liquid heat exchangers, including offset-strip fins as heat transfer enhancer (turbolator), has been developed. The main problem is represented by the need of considering different scales in the simulation, ranging from the characteristic size of the turbolator geometry (tipically µm – mm) to the full scale of the overall device (typically cm – dm). Therefore, the developed modeling approach is based on a multi-scale concept, which applies: a) detailed simulations, performed on a refined grid on a representative elementary volume (REV), to characterize the fluid-dynamic and heat-transfer properties of the turbolator and b) full-scale simulations, performed on a coarse grid which describes the entire component, applying a porous media approach for the modeling of the turbolator, with properties upscaled from the detailed analysis.
The model is firstly validated comparing with experimental data under different operating conditions. Then, it is adopted to investigate the details of the fluid-dynamics and heat-transfer process, providing guidelines for the optimization of the device.
Augusto Della Torre, Gianluca Montenegro, Angelo Onorati, Sumit Khadilkar, Roberto Icarelli
Politecnico di Milano, UFI Innovation Center, UFI Filters
14th International Conference on Engines & Vehicles