Electric Turbocharging for Energy Regeneration and Increased Efficiency at Real Driving Conditions

Abstract

Modern downsized internal combustion engines benefit from high-efficiency turbocharging systems for increasing their volumetric efficiency. However, despite the efficiency increase, turbochargers often lack fast transient response due to the nature of the energy exchange with the engine, which deteriorates the vehicle's drivability. An electrically-assisted turbocharger can be used for improving the transient response without any parasitic losses to the engine while providing energy recovery for increasing overall system efficiency. The present study provides a detailed numerical investigation on the potential of e-turbocharging to control load and if possible replace the wastegate valve. A parametric study of the optimum compressor/turbine sizing and wastegate area was performed for maximum torque, fast response time and energy regeneration across the real driving conditions speed/load area of the engine. The results showed that the implementation of a motor-generator could contribute to reducing the response time of the engine by up to 90% while improving its thermal efficiency and generating up to 6.6 kWh of energy. Suppressing the wastegate can only be achieved when a larger turbine is implemented, which as a result deteriorates the engine's response and leads to energy provision demands at low engine speeds.

Turbocompound Power Unit Modelling for a Supercapacitor-Based Series Hybrid Vehicle Application

“…In this scenario, not only fuel economy can increase using traditional ICEs, but series architecture can further benefit from turbocompound introduction, the benefits of which, in terms of efficiency, are relevant at high load, as observed by the modelling at Section 2 and by many works in the scientific literature [23][24][25][26][27][28]42].…”

“…Various studies also concern turbocompounds on spark-ignition engines. In [25] a theoretical analysis of turbocharging benefits on a 2000 cm 3 spark-ignition engine is shown whereas in [24] turbocharging benefits on a 1000 cm 3 spark-ignition engine are supported by experimental results.…”

“…This topology may further benefits from innovation in engine design, such as the introduction of turbocompound (TC) systems. As observed by Jain et al [23], turbocompound conditions are quite occasional in real road missions, thus, they do not render beneficial the introduction of the TC system; as a matter of fact, turbocompounding benefits are substantial at high load [23][24][25][26][27][28]. This aspect explains why today this technology is not used on medium size cars and is developed only for sportive cars or trucks and buses, characterized by frequent high load demand.…”

Why the Development of Internal Combustion Engines Is Still Necessary to Fight against Global Climate Change from the Perspective of Transportation

“…A revolution is approaching with respect to traditional gasoline and diesel engines making the boundaries between them disappear as deeper knowledge and greater control of the combustion process is acquired [34]. Advanced injection systems [35,36], turbochargers [37,38], organic Rankine cycles (ORC) [39], hybridization [40,41], multifuel solutions [42][43][44], or advanced combustion concepts are becoming a part of the ICE context. All these strategies are dedicated to extract every Joule of energy from the fuel.…”

Impact of Electrically Assisted Turbocharger on the Intake Oxygen Concentration and Its Disturbance Rejection Control for a Heavy-duty Diesel Engine

“…This helps to improve EGR inert quality and reduce transient soot/Nitrogen Oxides (NOx) emissions [18]. The electrically assisted turbocharger (EAT) is promising in enhancing boost response and recovering exhaust energy [4][5][6][7][8][9][10][11]. By mounting an electrical motor/generator (referred to as TEMG in this paper) in the shaft of conventional turbocharger, EAT is capable of bi-directional energy transfer.…”