Turbogenerator energy recovery model

Gasoline turbocharged direct injection (GTDI) engines waste significant exhaust enthalpy; even at moderate loads the WG (Wastegate) starts to open. This action is required to reduce EBP (Exhaust Back Pressure). Another factor is catalyst protection, placed downstream turbine. Lambda enrichment is used to perform this. However, the turbine has a temperature drop across it when used for energy recovery.

Since catalyst performance is critical for emissions, the only reasonable location for an additional device is downstream of it. This is a challenge for any additional energy recovery, but a smaller turbine is a design requirement, optimised to operate at lower pressure ratios.

A WAVE model of the 2.0L GTDI engine was adapted to include a TG (Turbogenerator) and TBV (Turbine Bypass Valve) with the TG in a mechanical turbocompounding configuration, calibrated with steady state dynamometer data to estimate drive cycle benefit using KP (Key Point) analysis. This includes power and fuel consumption, and additionally a sensitivity analysis and knock impact assessment. The model derived will be used in development of more advanced control system algorithms and prototype testing on dynamometer or vehicle could be performed to verify design assumptions and simulation results. Furthermore, transient verification with WAVE-RT and other drive cycles (WLTP, RDE), sensitivity at KP’s with respect to TBV setting, electrical turbo-compounding, interfacing to the power-grid, and calibration optimisation, using combined WG and TBV settings.