Comparative Parameters Evaluation of Internal Combustion Engines Naturally Aspired and Supercharged With Hybrid Turbocharger

Internal combustion engines have an operating eciency that can be exploited to increase their performance. Some of the waste gases can be recovered through technical solutions such as turbocharging. The turbocharging solution is one of the most popular technical solutions for increasing the energy performance of internal combustion engines. This requires an analysis of the energy balance of the internal combustion engine. This shows that there is a signicant reserve of energy in the exhaust gases, which can be used to increase the engine eciency. One solution is to use this energy to drive a turbine coupled with an electric generator. This article aims to present the result of the experimental research of the hybrid turbocharger, simulating and validating the new solutions for increasing the energy performance of internal combustion engines through hybrid turbochargers using a coupled electric generator. The simulations will be performed using AMESim software developed by Siemens to demonstrate through calculations the eciency of new solutions, such as a hybrid turbocharger. The tests will be performed using an diesel internal combustion engine with a cylinder capacity of 1.9 liters which is also simulated with AMESim software. The residual exhaust gases of the internal combustion engine will drive the hybrid turbocharger turbine and generate electricity. Electricity can then be used for storage in the car battery or for consumption by the car's electrical system. The article also includes a comparative study between the power and torque of the naturally aspirated internal combustion engine equipped with a hybrid turbocharger.


Introduction
The importance of water-cooled exhaust turbochargers will increase in the near future. Turbochargers are a key component in reducing fuel consumption. [1] The purpose of the turbocharger is to increase the amount of compressed air introduced into the engine cylinders. It can also be used as an engine brake for large trucks with diesel engines. Indeed, the cost and development time must be reduced to meet both customers target and strict emission standards. The current turbocharger simulation codes are largely based on the search tables (air ow and air mass) provided by the manufacturers. [2] In recent years, internal combustion engines have been developed, and expectations have increased, such as performance, pollution in relation to costs, so the research area has also expanded. [3] More energy e ciency and less polluting processes are needed in the internal combustion engine sector. Compression ignition engines are used in electricity generation, marine and transport and the Otto engine is used for transport, but in both cases, processes can be improved and made to allow for higher pressure ratios and also to generate electricity under su cient operating conditions. [4] One way to improve engine performance is to improve turbocharger performance. In this context, the gas turbocharger plays an important role in future designs, especially to reduce CO2 emissions. This is caused by the technical complexity of this device and also by the signi cant in uence of the turbocharger performance and fuel consumption of the engine. [5] The turbocharger was essential in the use of low-cylinder engines at high power. As an advantage of engines with lower displacement and fewer cylinders, we can mention both higher e ciency and lower volume. In gasoline car applications, in the past there was a clear trend of switching from four-cylinder engines to three-cylinder engines, but there was no de nite trend in the diesel engine segment. In off-road applications, the use of three-cylinder diesel engines continues to increase, and even two-cylinder engines are in series production. [6] Due to the heterogeneity of multi-part materials, manufacturing and assembly errors and uneven turbine carbon, a random imbalance can usually develop that will induce excessive rotor vibration and even lead to nonlinear vibrations. [7] For this the compressor-generator coupling manages to eliminate this problem. The in uence of shaft quality on the turbine and rotor was not taken into account in the dynamic model analysis process. The rotor of the turbocharger rotor was simpli ed rst, the different parts of the simpli ed rotor were analyzed and the dynamic model of the rotor was established. [8] The exhaust volume represents the entire volume of ports, manifold and turbine volute. [9] A hybrid turbocharger was built to demonstrate that the turbocharger has a great ability to improve, namely a turbocharger coupled to a speed ratio and an electric generator. ( gure 1) Table 1 contains all the important components of the hybrid turbocharger, such as: turbocharger components, speed ratio (1:10) and the 100W electric generator, also with the main symbols used by the simulation with AMESim software.
The main component parts of the turbocharger prototype, such as: turbocharger, speed ratio and electric generator presented directly as components, but also as simulation parts of the AMESim software.

Objetive
The general objective of this experimental work is to demonstrate that the turbocharger has a very good performance improvement. But to demonstrate this, the simulation and validation results of the hybrid turbocharger prototype must also be presented. The e ciency of the turbine is in uenced by different drives, depending on the number of cylinders. In addition, another in uence of the number of cylinders on the pumping losses was found. This effect strongly depends on the exhaust volume before the turbine, which is why the subject of constant pressure and turbo power supply must be examined in detail. It was found that a smaller number of cylinders (<4) has, in principle, higher pumping losses, even with the same turbocharger e ciencies. The lowest pump losses can be obtained with four-cylinder engines. It has also been shown that this problem is completely different for diesel and petrol engines. [10] The demand for continuous improvement of the transient performance of diesel engines requires a higher pressure and a more e cient turbocharger. [11] Also in gure 3 below are presented the components of the engine with internal combustion diesel of cylindrical capacity 1.9 liters naturally aspirated modeled by AMESim software. This is the reference model, then the results of the experimental data will be compared with the model developed by the AMESim software, namely the 1.9 liter cylindrical diesel internal combustion engine equipped with a hybrid turbocharger.
Also in gure 4 below are presented the components of the supercharged 1.9 liter diesel internal combustion engine equipped with a hybrid turbocharger modeled by AMESim software.

Methodology
The basic equations used for the mathematical simulation of the compressor, turbine and alternator can be divided into two categories namely for the mechanical part and for the electrical part.

Equations for the mechanical part
To take into account the real engine operating conditions, the rotary speed and the mass ow rate values are corrected or reduced.

Results
The waste gas energy will be transformed with the help of the hybrid turbocharger both in energy that with the compressor will compress air for the engine but also electricity with the help of the electric generator connected to the turbocharger shaft outside.
The results show the electrical parameters resulting from the rotation of the turbocharger, namely: current intensity, voltage and power output. This is the green energy produced by the turbocharger at a constant speed of 162400 revolutions per minute, with a resulting pressure of about 1 bar.

Conclusions
The new composite turbo systems for the automotive industry to recover the energy of the internal combustion engine have three basic elements: the extended shaft to engage the power generator at the blower end, a gear that reduces the rotation of the turbocharger and a cooling system for the generator that is optional.
Analyzing the values obtained through the experimental part and the simulation part, it can be stated that the turbocharger has a great potential to develop and obtain ecological electricity for the vehicle.
The hybrid turbocharger can be used with hybrid engines, but also for the classic solution of internal combustion engines.
Parallel sequential turbocharging systems can generate, they are able to operate in different ways, to generate electricity for the vehicle's electric motor both for consumption and to be stored in batteries. [14] The main advantages of the new hybrid turbocharger are: the consumption of green electricity and storage in the main battery of the vehicle, it also redirects to the peripheral consumers of the computer and the compression of the air for the engine.    Alternator symbol and main parameters in AMESim Software Figure 6 The current intensity, the voltage and the power from the experimental results in relation to time The current intensity, the voltage and the power from the simulation results in relation to time  The speed rotor shaft in rotation per minute, rpm simulated with AMESim in relation to time Figure 10 The compressor outlet pressure from the experimental results in relation to time Figure 11 The compressor outlet pressure simulated with AMESim Figure 12 Comparison between rated power naturally aspirated / turbo hybrid engine and generator load at 100% load Figure 13 Comparison between natural naturally aspirated engine and hybrid turbo at 100% load  The torque at load 100% simulated with the AMESim software of the naturally aspirated Diesel 1.9 engine Figure 16 Rated engine power at 100% load simulated with AMESim software of Diesel 1.9 engine equipped with hybrid turbocharger