Hybrid turbocharging as a technology to reduce co2 from internal combustion engines investigated by 1D numerical model

One of the last EU targets in the field of GHGs emission control in transports is the reduction of CO2 emission about 4%/year for the next years until 2030. This implies an enhancement of the engine efficiency and, accordingly, an improvement of the technology used. In this framework, hybrid powertrains have the possibility of a deep market penetration since they may recover energy during the braking phase, thus allowing the engine to operate in better efficiency conditions and with less transients. Moreover, they can recover a large amount of energy lost through the exhaust and use it to reduce fuel consumption. The proposed work concerns the modelling and simulation of a hybrid turbocharged internal combustion engine. In the studied configuration, a classical turbocharged Diesel engine is coupled with an electric motor that can be uses both as generator and as motor. As a generator, it is driven by the turbine to supply an additional amount of power to the powertrain or to the battery; besides, taking energy from the battery it can act as driver for turbocharger thus providing an extra power to the engine. Previous works have shown the benefits for heavy-duty engines using the energy for the auxiliaries, while in the present work we will study the potential benefits of adopting the described configuration and using the additional power from the turbine to increase the engine efficiency. To quantify the advantages two driving cycles, namely the NEDC and the WLTC, have been simulated using as input the engine maps derived by a 1D engine simulation model, considering power, torque, consumption and efficiency on a commercial passenger vehicle. To this aim, an in-house code (EngineSim) was used. EngineSim can simulate the behavior of a turbocharged four-stroke engine using a one-dimensional compressible flows model and a two zones combustion model.