Exhaust gas is recirculated in an internal combustion engine to improve NOx emissions from the engine. The recirculated exhaust gas is mixed with the intake air and fuel. Mixing the recirculating the exhaust gas with the intake air dilutes the air by lowering the oxygen concentration and reduces the peak combustion temperature experienced in the combustion chamber of the internal combustion engine. While the recirculated exhaust gas reduces the NOx emissions it can reduce fuel efficiency and increase particulate matter emissions, hydrocarbon emissions, carbon monoxide emissions, and wear on various components of the engine.
EGR systems may be provided upstream of a turbine and a compressor of an internal combustion engine, in a format generally referred to as a high pressure loop EGR system in view of the higher pressures that the exhaust gas is at pre-turbine. EGR systems may also be provided downstream of a turbine and compressor of an internal combustion engine, in a format generally referred to as a low pressure loop EGR system in view of the lower pressures that the exhaust gas is at post-turbine with respect to the pressure of the exhaust gas pre-turbine in the high pressure loop EGR system. While low pressure loop EGR systems generally have better brake thermal efficiency (BTE) than high pressure loop systems, low pressure loop EGR systems also have greater susceptibility to condensation generation, which condensation or liquid water in the system is highly detrimental to performance and life of the turbocharger or supercharger compressor.
USPTO Backgrounds
USPTO Backgrounds