Performance analysis of turbocharger effect on engine in local cars

The performance of a gasoline-fueled internal combustion engines can be increased with the use of a turbocharger. However, the amount of performance increment for a particular engine should be studied so that the advantages and drawbacks of turbocharging will be clarified. This study is mainly concerned on the suitable turbocharger unit selection, engine conversions required and guidelines for testing a Proton 4G92 SOHC 1.6-litre naturally aspirated gasoline engine. The engine is tested under its stock naturally aspirated condition and after been converted to turbocharged condition. The effect of inter cooled turbocharged condition is also been tested. Boost pressure is the main parameter in comparing the performance in different conditions as it influences the engine torque, power, efficiency and exhaust emissions. The use of a turbocharger on this test engine has clearly increased its performance compared to its stock naturally aspirated form. The incorporation of an intercooler to the turbocharger system increases the performance even further. With the worldwide effort towards environmental-friendly engines and fossil fuel shortage, the turbocharger can help to create engines with enhanced performance,minimum exhaust emissions and maximum fuel economy

Investigation of performance and characteristics of a multi-cylinder gasoline engine with controlled auto-ignition combustion in naturally aspirated and boosted operation

This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University.Controlled Auto-Ignition (CAI) also known as Homogeneous Charge Compression Ignition (HCCI) is increasingly seen as a very effective way of lowering both fuel consumption and emissions. Hence, it is regarded as one of the best ways to meet stringent future emissions legislation. It has however, still many problems to overcome, such as limited operating range. This combustion concept was achieved in a production type, 4-cylinder gasoline engine, in two separated tests: naturally aspirated and turbocharged. Very few modifications to the original engine were needed. These consisted basically of a new set of camshafts for the naturally aspirated test and new camshafts plus turbocharger for the boosted test. The first part of investigation shows that naturally aspirated CAI could be readily achieved from 1000 to 3500rpm. The load range, however, decreased noticeably with engine speed due to flow restrictions imposed by the low lift camshafts. Ultra-low levels of NOx emissions and reduced fuel consumption were observed. After baseline experiments with naturally aspirated operation, the capability of turbocharging for extended CAI operation was investigated. The results show that the CAI range could achieve higher load and speed with the addition of the turbocharger. The engine showed increased fuel consumption due to excessive pumping losses. Emissions, however, have been reduced substantially in comparison to the original engine. NOx levels could be reduced by up to 98% when compared to a standard SI production engine.CAPE

Numerical and experimental study of a boosted uniflow 2-stroke engine

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel UniversityEngine downsizing is one of the most effective ways to reduce vehicle fuel consumption. Highly downsized (>50%) 4-stroke gasoline engines are constrained by knocking combustion, thermal and mechanical limits as well as high boost. Therefore a research work for a highly downsized uniflow 2-stroke engine has been proposed and carried out to unveil its potential. In this study, one-dimensional (1D) engine simulation and three-dimensional (3D) computational fluid dynamic analysis were used to predict the performance of a boosted uniflow 2-stroke DI gasoline engine. This was experimentally complemented by the in-cylinder flow and mixture formation measurements in a newly commissioned single cylinder uniflow 2-stroke DI gasoline engine. The 3D simulation was used to assess the effects of engine configurations for engine breathing performance and in order that the design of the intake ports could be optimised. The boundary conditions for 1D engine simulation were configured by the 3D simulation output parameters, was employed to predict the engine performance with different boost systems. The fuel consumption and full load performance data from the 1D engine simulation were then included in the vehicle driving cycle analysis so that the vehicle performance and fuel consumption over the NEDC could be obtained. Based on the modelling results, a single cylinder uniflow 2-stroke engine was commissioned by incorporating a newly designed intake block and modified intake and exhaust systems. In-cylinder flow and fuel distribution were then measured by means of Particle Image Velocimetry (PIV) and Planar Laser Induced Fluorescence (PLIF) in the single cylinder engine. The numerical analysis results suggested that a 0.6 litre two-cylinder boosted uniflow 2-stroke engine with an optimised boosting system was capable of delivering comparable performance to a NA 1.6 litre four-cylinder 4-stroke engine yet with a maximum 23.5% improvement potential on fuel economy. Furthermore, simulation results on in-cylinder flow structure and fuel distribution were then verified experimentally

Analysis of combustion phenomena and knock mitigation techniques for high efficient spark ignition engines through experimental and simulation investigations

Different technologies are being utilized nowadays aiming to boost the fuel efficiency of Spark-Ignition (SI) engines. Two promising technologies which are used to improve the part load efficiency of SI engines are the utilization of downsizing in combination with turbocharging and cylinder deactivation. Both technologies allow a shift of load points towards higher loads and therefore towards more efficient zones of the engine map, while performance is being preserved or even enhanced despite the smaller displacement thanks to high boost levels. However, utilization of both technologies will increase the risk of knock dramatically. Therefore, the abovementioned systems can be coupled with other technologies such as gasoline direct injection, Miller cycle and water injection to mitigate knock at higher load operating conditions. Therefore, the aim of the current work is to investigate, through experimental and numerical analysis, the potential benefits of different knock mitigation techniques and to develop reliable and predictive simulation models aiming to detect root cause of cyclic variations and knock phenomena in downsized turbocharged SI engines. After a brief introduction in Chapter 1, three different typical European downsized turbocharged SI engines have been introduced in Chapter 2, which were used for both experimental and simulation investigations, named as Engine A, which is downsized and turbocharged, Port Fuel Injection (PFI) with fixed valve lift and represents the baseline; Engine B, represents an upgraded version of Engine A, featuring Variable Valve Actuation (VVA), and Engine C which is a direct injection and further downsized engine. Engine B, equipped with MultiAir VVA system, was utilized to evaluate the possible benefits of cylinder deactivation in terms of fuel economy at part load condition, which is discussed in Chapter 3. Since the MultiAir VVA system does not allow exhaust valve deactivation, an innovative strategy was developed, exploiting internal Exhaust Gas Recirculation (iEGR) in the inactive cylinders in order to minimize their pumping losses. However, at higher load operating condition, risk of knock occurrence limits the performance of the engine. Therefore, the possible benefits of different knock mitigation techniques such as Miller Cycle and water injection in terms of fuel consumption were discussed in Chapter 4. Potential benefits of Miller cycle in terms of knock mitigation are evaluated experimentally using Engine B, as shown in Chapter 4.2. After a preliminary investigation, the superior knock mitigation effect of Late Intake Valve Closure (LIVC) with respect to Early Intake Valve Closure (EIVC) strategy was confirmed; therefore, the study was mainly focused on the latter system. It was found out that utilization of LIVC leads up to 20% improvement in the engine indicated fuel conversion efficiency. Afterwards, Engine C, a gasoline direct injection engine, has been utilized in order to understand the potential benefits of water injection for knock mitigation technology coupled with the Miller Cycle, which is discussed in Chapter 4.3. Thanks to water injection potential for knock mitigation, the compression ratio could be increased from 10 to 13, which leads to an impressive efficiency improvement of 4.5%. However, utilization of various advanced knock mitigation techniques in the development of SI engines make the system more complex, which invokes the necessity to develop reliable models to predict knock and to find the optimized configuration of modern high-performance, downsized and turbocharged SI engines. Considering that knock is strictly related to Cycle-to-Cycle Variations (CCV) of in-cylinder pressure, CCV prediction is an important step to predict the risk of abnormal combustion on a cycle by cycle basis. Consequently, in Chapter 5, a procedure has been introduced aiming to predict the mean in-cylinder pressure and to mimic CCV at different operating conditions. First, a 0D turbulent combustion model has been calibrated based on the experimental data including various technologies used for knock mitigation which can impact significantly on the combustion process, such as Long Route EGR and water injection. Afterwards, suitable perturbations are adapted to the mean cycle aiming to mimic CCV. Finally, the model has been coupled with a 0D knock model aiming to predict knock limited spark advance at different operating conditions. Finally, in order to provide a further contribution towards the prediction of CCV, 3D-CFD Large Eddy Simulation (LES) has been carried out in order to better understand the root cause of CCV, presented in Chapter 6. Such analysis could be used to extract the physical perturbation from the 3D-CFD and to use it as an input for the 0D combustion model to predict CCV. The operating condition studied in this work is at 2500 rpm, 16 bar brake mean effective pressure (bmep) and stoichiometric condition. Based on the analysis conducted using LES, it was found out that the variability in combustion can be mainly attributed to both the direction of the velocity flow-field and its magnitude in the region around the spark plug. Furthermore, the effect of velocity field and equivalence ratio on the combustion has been decoupled, confirming that the former has the dominant effect while the latter has minor impact on combustion variability. In conclusion, simulation models using 0D and 3D-CFD tools when calibrated properly based on experimental measurements can be used to support the design and the development of innovative downsized turbocharged SI engines considering the effects of CCV and knock on engine performance parameters

FSAE TURBO-SYSTEM DESIGN 2010

The goal of this project was to determine the performance gains associated with adding a turbocharger to a naturally aspirated engine, used in a Formula SAE race car. This involved selecting the correct turbocharger for the engine, designing and fabricating the entire turbo-system, selecting and configuring an engine management system, tuning various engine variables, and performing before and after tests to determine any performance gains. This project was meant to provide future teams with design information to help them determine whether or not using a turbocharger is a viable design consideration

Effects of fuel composition on charge preparation, combustion and knock tendency in a high performance GDI engine. Part I: RANS analysis

The paper analyses the effects of fuel composition modelling in a turbocharged GDI engine for sport car applications. Particularly, a traditional single-component gasoline-surrogate fuel is compared to a seven-component fuel model available in the open literature. The multi-component fuel is represented using the Discrete-Continuous-Multi-Component modelling approach, and it is specifically designed in order to match the volatility of an actual RON95 European gasoline. The comparison is carried out following a detailed calibration with available experimental measurements for a full load maximum power engine speed operation of the engine, and differences are analyzed and critically discussed for each of the spray evolution, mixture stratification and combustion. In the present paper (Part I), a RANS approach is used to preliminarily investigate the behaviour of the fuel model on the average engine cycle. In the subsequent Part II of the same paper, the numerical framework is evolved into a more refined LES approach, in order to take into account cycle-to-cycle variations in mixture formation and knock tendency

FSAE TURBO-SYSTEM DESIGN 2010

The goal of this project was to determine the performance gains associated with adding a turbocharger to a naturally aspirated engine, used in a Formula SAE race car. This involved selecting the correct turbocharger for the engine, designing and fabricating the entire turbo-system, selecting and configuring an engine management system, tuning various engine variables, and performing before and after tests to determine any performance gains. This project was meant to provide future teams with design information to help them determine whether or not using a turbocharger is a viable design consideration

Engine Downsizing; Global Approach to Reduce Emissions: A World-Wide Review:A World-Wide Review

Engine downsizing is a promising method to reduce emissions and fuel consumption of internal combustion engines. The main concept is to reduce engine displacement volume while keeping the needed output characteristics unchanged. The issue has become one of the most current fields of interest in recent years after the International Energy Agency set a target of a 50% reduction in global average emissions by the year 2030. In this review paper, different aspects of researchers’ efforts on engine downsizing are configured and, due to overlaps, categorized into five main areas. Each category is discussed thoroughly, and recent works are highlighted. The global attention in these categories, the countries involved and the trend change in the last four years are presented in detail. Doi: 10.28991/HIJ-2021-02-04-010 Full Text: PD

Efficiency advantages of the separated electric compound propulsion system for CNG hybrid vehicles

As is widely known, internal combustion engines are not able to complete the expansion process of the gas inside the cylinder, causing theoretical energy losses in the order of 20%. Several systems and methods have been proposed and implemented to recover the unexpanded gas energy, such as turbocharging, which partially exploits this energy to compress the fresh intake charge, or turbo-mechanical and turbo-electrical compounding, where the amount of unexpanded gas energy not used by the compressor is dedicated to propulsion or is transformed into electric energy. In all of these cases, however, maximum efficiency improvements between 4% and 9% have been achieved. In this work, the authors deal with an alternative propulsion system composed of a CNG-fueled spark ignition engine equipped with a turbine-generator specifically dedicated to unexpanded exhaust gas energy recovery and with a separated electrically driven turbocompressor. The system was conceived specifically for hybrid propulsion architectures, with the electric energy produced by the turbine generator being easily storable in the on-board energy storage system and re-usable for vehicle traction. The proposed separated electric turbo-compound system has not been studied in the scientific literature, nor have its benefits ever been analyzed. In this paper, the performances of the analyzed turbo-compound system are evaluated and compared with a traditional reference turbocharged engine from a hybrid application perspective. It is demonstrated that separated electric compounding has great potential, with promising overall efficiency advantages: fuel consumption reductions of up to 15% are estimated for the same power output level