Boost System Development for Gasoline Direct-Injection Compression-Ignition (GDCI)

Intake boosting is an important method to improve fuel economy of internal combustion engines. Engines can be down-sized, down-speeded, and up-loaded to reduce friction losses, parasitic losses, and pumping losses, and operate at speed-load conditions that are thermodynamically more efficient. Low-temperature combustion engines (LTE) also benefit from down-sizing, down-speeding, and up-loading, but these engines exhibit very low exhaust enthalpy to drive conventional turbochargers. This paper describes modeling, evaluation, and selection of an efficient boost system for a 1.8L four-cylinder Gasoline Direct-Injection Compression-Ignition (GDCI) engine. After a preliminary concept selection phase the model was used to develop the boost system parameters to achieve fullload and part-load engine operation objectives. The simulation was used to demonstrate that a practical boost system can provide the boost necessary at reasonable brake efficiency levels over the entire engine operating range. A comprehensive simulation based calibration was performed to determine the most efficient steady operation settings. Also a step change in speed/load engine operation was simulated to demonstrate the system transient response.