# Advanced Engine Technologies for Turbochargers Solutions
## 1 Introduction  
Research in the process of internal combustion engines shows that their efficiency can be increased through several technical and functional solutions. After preliminary investigations of the performance of engines equipped with advanced axial turbocharger turbines [1, 2], it was considered that turbochargers have a huge development potential. Hybrid power trains for city cars were also developed in tight contact with turbocharger systems [3]. Furthermore, these applications were made for hybrid city cars [4]. The center development area was the turbocharger, which was tested with experimental and CFD calculation for better performances optimization [5].  
Relatively recently, the idea that exhaust gases from the tailpipes of internal combustion engines can be used as an energy source has been advanced. Normally, a turbocharger has the role of helping to introduce a greater amount of fresh air into the cylinders of an engine and at the same time to reduce emissions [6]. Moreover, they can be used to produce electricity. In the literature there are very few references to this technology, which seems to have been used since 2012, in the case of a Jaguar XJR-15 equipped with YGK EER-Hybrid system [7]. A similar system was used by Mercedes for the AMG Project One Formula 1 model. The electric flue gas turbocharger used an excessive part of the flue gas flow to generate electricity as an alternator and to store it either by recovery in the high voltage lithium-ion battery or to transmit it as additional propulsion to another electric motor [8]. This process of energy recovery through the turbocharger and the scientific works dealingwith this aspect is presented in [3]. This technology has also been applied to natural gas marine engines [9].  
The aim of this paper is to present the results of the experimental research of a hybrid turbocharger, simulating and validating the new solution for increasing the energy performance of the internal combustion engine through hybrid turbochargers using a coupled electric generator. The simulation will be performed using AMSEim software developed by Siemens and the test will be performed using a diesel internal combustion engine with a cylinder capacity of 1.9 L. The article also includes a comparative study between the power and torque of the naturally aspirated internal combustion engine equipped with a hybrid turbocharger.  
The main focus in this work lies in affirming the electrical energy generation from the exhaust gasses of the internal combustion engine through the turbocharger and showing the great exploitation potential of the turbocharger (which has a high mechanical efficiency).  
There are many constructive solutions for electrical turbochargers with the generator positioned between the compressor and the turbine wheel [10]. This paper presents a solution of a hybrid turbocharger with the generator positioned and coupled with the compressor wheel on the exterior side. This is a much better solution since the solution with an electric generator placed between the compressor and the turbine is blocked due to the heat transfer from the turbine (this being an unreliable constructive solution). This electric turbocharger solution is used to recover energy as well as to increase the efficiency of the internal combustion engine system [11].  
Another problem implicitly solved by this constructive solution is the significant decrease of the vibration of the compressor and the turbine system. The vibration of the turbine rotor and compressor wheel was stabilized by the external fixing points by coupling with gear ratio and also by the generator [12].