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Flexible fuel vehicles have been a challenge for the automotive industry due to the chemical properties of ethanol combustion. Especially on days in which the ambient temperature is below 18 degree Celsius, flexible fuel starting is critical due to high ethanol flash point. To solve this problem, cold start systems have been implemented in flexible fuel vehicles. Cold start systems that inject gasoline to assist in starting have been widely used. However, they dramatically increase the level of pollutant emissions during the cold start phase and they depend on the driver interactivity to refill the system with gasoline. Cold start systems using electric pre-heating have been recently launched into the automotive industry.

The flex-fuel engine technology evolution and bio fuels increasingly market presence brings new challenges on components development requirements. One of the affected products is the fuel filter, where downsizing, dust holding capacity and filtration efficiency are the improvement goals. In order to attend these market demands, MAHLE has developed a new flex-fuel filter generation. This new product is able to double the dust holding capacity while maintaining the filtration efficiency. In addition, new product dimensions, like body diameter and distance between inlet and outlet, are the same found in current solutions. In this way, it can be used in many vehicles with none or few modifications at interface components. First optimization was done through changes in filter housing design and fuel system line connectors. Second optimization was single layer cellulose media improvement to multilayer concept.

The proposed paper aims to present the three-dimensional CFD analysis of flow inside an automotive air filter conducted by SMARTtech Fluidos for SOGEFI Filtration do Brasil Ltda., in order to determine the pressure drop over an AIS (Air Intake System). Two geometries have been analyzed in seven operation conditions, each. The flow was considered steady-state, incompressible, turbulent and isothermal. The region occupied by the filter element was treated as a porous medium and the porosity coefficients were extracted from experimental results. The contribution given by each component to the total pressure drop was determined.