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Engine cooling by nucleate boiling requires a profound knowledge of cooling systems components: heat exchangers, water pumps, eventually liquid-vapor separators, on the part of equipment manufacturers. Experimental and theoretical studies of the principal heat exchanger, I.E., the vapor-condensor, were effected. The experimental phase required the development, after careful study, of a test set-ups specifically designed for vapor-condensors. Tests are conducted under controlled intake pressures and temperatures, and sub-cooled outlet conditions. Under varying air-flows, outlet-liquid measurements yield instructive information relative to exchanger thermic performance. The influence on performance of tube shape, direction of liquid circulation (horizontal or vertical) and number of passes was also studied. Concurrently, thermic visualization by infra-red camera permits qualitative evaluation of vapor distribution within the condenser.

The targets of this study are: cost reduction of all engine cooling components, gasoline consumption reduction, weight reduction of the engine cooling system, improvement of the thermal comfort in passenger compartment. To reach these targets, Valeo Engine Cooling is developing a new concept in engine cooling. This basic concept consists of adding a small electric water pump, 30 to 60W, instead of the conventional engine driven water pump of up to 1 to 2 KW. This small electric water pump provides a flow rate of approximately 1000L/h. With a liquid flow rate of 1000L/h, this conceptual system can ensure engine cooling at speeds up to 120 Km/h under convective cooling in normal conditions. That is to say, it can supply 95% of the flow requirements (see appendix ) of a vehicle at the same performance level as a conventional cooling system.