Search Results

Exhaust Gas Recirculation - EGR - is a well-known technique to reduce NOx and it’s been applied on Diesel engines for a long time. Later studies and application found that other benefits can be achieved with PFI and GDI gasoline engines, such as pumping loss minimization and efficient knock control. Variable valve actuation valve-trains brought broader application possibilities as it enables full internal EGR control without external paths, high precision and response, as required on transient work modes. Comprehensive investigation on PFI and GDI Spark Ignition engines with external Hot EGR and Cooled EGR are widely available. However, variable valve actuation EGR control review on a flexfuel application is not well explored, and this paper is aimed at doing such.

Port fuel injection - PFI - engines are widely available and the calibrations of fuel models are well defined. Modern flex-fuel engines are designed to work with different fuels and a mix of them. However, Brazil’s ethanol is composed of anhydrous Ethanol mixed with 8% distilled water, making it distinct in relation of composition. In a PFI, the fuel mass is mixed to the air mass before entering the combustion chamber in order to keep the mixture most uniform as possible. In this process, heat exchange and partial pressure variation are present and this may lead to volumetric efficiency modification. However, measurement errors may be introduced from the indirect measurement method if it does not considers water content and combustion efficiency to determine volumetric efficiency.