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The previous study presented during the last VTMS 4 showed the following results, for all engine cooling system and depending on the vehicles: Cost reduction by - 10 to -15%, Weight reduction by -15 to - 21%, Coolant volume reduction by -25% Fuel consumption by -3%, Thermal comfort improvement. Despite of these good results, most of car manufacturers hesitated to use this new concept due to this technological breakthrough of engine cooling system because of expensive durability studies. In this paper the electric fan has been simply suppressed and replaced by the heating blower allowing to cool the engine at idle and at low vehicle speed. By suppressing the electric cooling fan, the advantages of this new economical engine cooling system become: cost reduction up to - 30%, weight reduction up to - 30%.

The cooling conditions of electric vehicles are completely different when compared to the cooling conditions of internal combustion engines for passenger cars, particularly the liquid flow rate and the coolant temperature. The electric vehicle has a flow rate of approximately 500 L/h at low coolant temperatures and the internal combustion engine may have a flow rate as high as 5 000 L/h at high coolant temperature. Without optimization the same size radiator for the heat dissipation for an internal combustion engine of 30 kW can only satisfy 3 kW of heat dissipation for the electric vehicle. We have developed two solutions to cool the electric vehicle: A conventional cooling solution by using the same cooling liquid mixture, Ethylene Glycol-water 50-50%, that is to say, we adapted and optimized the cooling radiator for low flow rate and low coolant temperature. An evaporative cooling solution by using a new fluid, called, Fluorinert FC72.

In order to reduce the cost of engine cooling systems in particular the turbo Diesel engines with charge air coolers, we want to understand the relationship between oil sump temperatures and engine coolant temperatures and their impact on one another. Several cars have been tested in the climatic wind tunnel. The following are the cooling specifications: hill climbing with 12% grade with or without a trailer at a 20°C ambient max. speed at 35°C ambient. The main results of these studies were: a great variation of oil sump temperature versus coolant temperature a small variation of coolant temperature versus oil sump temperature a very small variation of heat flux in the oil, in the coolant and the output of engine versus oil sump and coolant temperature.

This paper deals with engine evaporative cooling on the VW TDI diesel engine at high heat rejection running points. Engine tests and thermohydraulic 3D computations inside the engine head are used. First, the basic engine is studied. Then, the flow rate corresponding to evaporation is determined. Around this flow rate, the influence of inlet coolant temperature and circuit pressure are studied. The engine tests and 3D calculations give hydraulic ways of improvements consisting in balancing the flows around the different cylinders. Geometrical modifications of the inside engine circuit (gasket....) are then tested to achieve these improvements.