| Popis: |
In perspective of the incoming CO 2 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 front module constituted by heat exchangers carrying different fluids (e.g. water-glycol, air, refrigerant fluid…), is replaced by a two coolant-to-air exchangers module 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 minimising the tube lengths and refrigerant charge. In addition, the coolant thermal inertia reduces the temperature fluctuations of the engine intake air temperature. These effects compensates the introduction of an intermediate temperature level allowing to reduce the overall vehicle fuel consumption in real use and could enable the front aerodynamic improvement. The experimental results show that it is possible to reduce the fuel consumption of up to the 4% when the air conditioning is operating and to reduce the refrigerant charge of up to the 30%. In the paper is described the system concept and the experimental results related to an application on a Fiat 500 are discussed highlighting the benefits and the open issues. |
