To improve the performance of a variable geometry turbocharged SI engine by porous material application

Abstract

• The fuel economy of the turbocharged gasoline engine was improved by using porous material. • The reduced exhaust temperature by using porous material expanded the equivalent ratio combustion range of the engine. • The porous material enhanced the high-temperature stability and durability of the variable geometry turbocharger (VGT). • The peak torque of the engine was improved by using porous material. As an effective method to improve engine performance at low engine speed, and reduce fuel consumption, VGT has been widely used in diesel engines. However, due to the higher exhaust temperature of the gasoline engines, it still has challenges of application in the turbocharged gasoline engines. As the high temperature of exhaust gas could damage the components of the complex variable structure in VGT, which may result in being deteriorated after long-term use of VGT. To improve the durability of VGT, researchers have been considering enhancing the high-temperature stability and durability by new components of the variable structure or advanced material for VGT production. In this study, a kind of porous material was installed before the turbine to study the effects on VGT application in a 4-cylinder turbocharged gasoline engine. As a result, using porous material, under the steady condition of medium load at 3200 RPM, a fuel economy improvement of about 1% was obtained due to the higher turbine efficiency and less pumping loss, and a 33 ℃ turbine inlet temperature decrease occurred due to the extra heat loss by adding porous material. In addition, under a high load of 4000 RPM, due to the decreased turbine inlet temperature by using of porous material, the stoichiometric combustion range of the engine was expanded, and peak torque was increased by a 25 ℃ lower turbine inlet temperature with porous material than the highest turbine inlet temperature limit. As a result, porous Si-SiC material could improve the fuel economy, high-temperature durability, and peak torque of the VGT engines.