Advanced Dual Level Vehicle Heat Rejection System for Passenger Cars 2012-01-1204

In perspective of the incoming CO₂ emission regulation, the on-board heat management is becoming even more relevant to assure the engine performance improvement minimizing the impact on the vehicle lay out, cooling drag and cost. The paper highlights the benefit of dual-level heat rejection system where the conventional front module is replaced by two coolant-to-air exchangers and where the charge air cooler and condenser are liquid-cooled. This approach allows to review the engine bay design allowing a deeper integration level: the charge air cooler can be integrated in the air intake manifold while the condenser can be placed near the compressor minimizing the tube lengths and refrigerant charge. In addition, the coolant thermal inertia reduces the temperature fluctuations of the engine intake air temperature. These effects compensate the introduction of an intermediate temperature level allowing reducing the overall vehicle fuel consumption in real use and could enable the front aerodynamic improvement. The paper is focused on the system description and on the result acquired validating two B-segment prototypes one having a diesel engine and the other having a gasoline engine. The experimental results show that the approach allows to improve the vehicle performance, simplify the engine bay lay out and to reduce the fuel consumption of up to the 4% when the air conditioning is operating. These results complete the integrate the work presented in 2011 at the VTMS.