Waste Gate Research Articles

Experimental investigation of the matching boundary and optimization strategy of a variable geometry turbocharged direct-injected hydrogen engine

With the higher demand for torque, power, brake thermal efficiency (BTE), and low NOx emissions of hydrogen engines, direct injection and turbocharging are the most effective methods to improve performance. However, due to the large air flow rate variation range with lean combustion and low exhaust gas energy, the turbine needs to be adjusted significantly, and the performance of the conventional waste gate turbochargers is limited. In this study, a 2.0 L direct-injected turbocharged hydrogen engine was studied experimentally and matched with a variable geometry turbocharger (VGT). The working boundary of the VGT determined by abnormal combustion and exhaust back pressure is proposed at all working conditions as it changes from 10-50 % @1500 rpm to 40–75 % @4500 rpm. Control of the VGT to balance combustion and gas exchange was achieved to reach the highest BTE of 42.57 %. Further, high torque of 326 Nm and high power of 125 kW are explored and different VGT opening strategies are compared. An optimized VGT opening control strategy is proposed, which is divided into five regions at different loads to ensure best performance. The VGT opening control strategy based on λ control and the trade-off between combustion and gas exchange efficiency at all working conditions can be valuable in the development of high-performance hydrogen engines.

On the impact of turbocharger thermo-mechanical limitations on new generation gasoline engines

Among other advances in spark ignited internal combustion engines’ field, the variable geometry turbine (VGT) is being analysed to achieve further CO2 reduction objectives. This paper analyses the potential implications of replacing nowadays standard, the waste-gate (WG) technology, with VGT.To do so, after developing a robust and validated model, this work proposes a methodology to optimize the variable valve timing (VVT), at full load working conditions, in a new generation spark ignited (SI) engine, coupled to a VGT prototype. The optimization methodology accounts for the different thermo-mechanical limits of such technology compared to the reference WG turbocharger, particularly in terms of the turbine inlet temperature (T3). Torque differences show a systematic improvement by using a VGT, reaching approximately 22 Nm of improvement and about 17 g/kWh, although the difference in torque is smaller after 3500 rpm due to the more restrictive T3 limit imposed.As well, at partial loads, the same procedure is developed, but targeting the optimization of the engine efficiency. At partial loads, when no exhaust gas recirculation technique is applied, few advantages are identified. However, with exhaust gasses recirculation (EGR) technique, improvements reach 3 g/kWh and permit extending the desired EGR rate towards the lower speeds.

A New Simulation-Based Methodology to Improve Medium-Speed Diesel Engines BSFC/NOx Tradeoff With an Optimized Air Charging System

Abstract This paper aims at introducing an original, simulation based, methodology to optimize air charging system of a medium speed engine in order to improve fuel consumption/NOx tradeoff, over a given load profile. A preliminary study is performed on an engine originally equipped with fixed geometry turbocharger (TC) matched at full load. It shows that improving the TC efficiency has a positive impact at matching point but an adverse effect at lower loads. Therefore, matching the TC at part load is more promising when the whole engine operating range is considered. However, this requires using a relief system to avoid unacceptable peak firing pressure (PFP) at full load, and may alter regulated NOx emission. A new, original methodology is then proposed. Using an advanced existing algorithm, it allows for simultaneous optimization of injection timing, main TC matching and relief system design. The objective is to minimize fuel consumption averaged over several operating points (corresponding to actual load profile). At the same time, NOx emission, evaluated on regulatory cycle, is kept below a given limit and others reliability constrains are fulfilled. The methodology is assessed with several case studies: • First, various relief systems (blow-off valve, waste gate (WG) and parallel sequential turbocharger (PTC)) are compared on a given load profile. • Then, the dimensioning of a TC + WG system is performed for two different load profiles. In both cases, the proposed methodology leads to a charging system design customized for a given user profile, which enables a significant fuel consumption reduction.

Assessment of hydrogen production from municipal solid wastes as competitive route to produce low-carbon H2

An economic and CO2 emission impact assessment of the production of H2 from municipal solid waste in the two configurations of retrofitting an existing waste to energy plant with an electrolysis unit (WtE + El) and of hydrogen production via waste gasification (WtH2) is made with respect to reference cases of H2 production by steam reforming of methane (SMR) or of water electrolysis (El). The results are analyzed with reference to two scenarios depending on whether the fate of waste disposal emissions for SMR and El is accounted. The costs of H2 production as a function of waste gate fee and CO2 taxation as well as the CO2 emissions for both scenarios and the four cases of H2 production analyzed are reported. The results show that produce H2 from a WtE plant hybridized with an electrolyzer could be economic only when the plant is free from depreciation costs and no CO2 taxation exists. Conversely, WtH2 solution results preferable when CO2 taxation will be applied to the non-biogenic fraction of waste. Conditions when WtH2 may results competitive to SMR are defined, in terms of both cost of production and CO2 emissions. With respect to El case, WtH2 results more competitive under the assumption made in terms of combined costs and CO2 emissions.

A diesel engine air path model with a WG and an ETV for exhaust temperature controller design and embedded control

In this paper a mean value model of a turbocharged diesel engine air path with an electric wastegate (WG) and an exhaust throttle valve (ETV) is presented. The model is designed with regard to system analysis, controller design, and real-time feasibility. That means, care is taken to ensure that the model contains the relevant dynamics on the one hand and that the requirements for computing power and memory (RAM) are kept as low as possible on the other hand. New approaches for modeling the ETV and the exhaust gas temperature are presented. The latter is formulated via an artificial neural network (ANN) computed outside the model. The ANN is integrated into the model in such a way that the differentiation of the model still provides meaningful results for controller design. Thus, this model may also be used for online computation of nonlinear model predictive controllers (MPC) or nonlinear state observers. The parameters of the model are determined using GT-Power simulation data covering the entire working range of the engine. Only measured variables that are also accessible on the engine test bench are used. All optimization problems to be solved within the parameter determination are presented. It is analyzed which sensors are suitable to support the model in an implementation on an electronic control unit (ECU), and the effect without and with sensor correction is shown in a dynamic test bench measurement. Furthermore, the properties of the generated C code are presented, which are the number of mathematical operations, the runtimes, and the stack size. An evaluation of the real time capability is given based on eigenvalue analyses and the properties of the C code .

Nonlinear Model Predictive Control of Mild Hybrid Powertrains With Electric Supercharging

Energy management plays a decisive role in the design of efficient 48V mild hybrid drives owing to the limited amounts of energy and power. In particular, strong nonlinearities of an electrified engine air path and the high interaction between the 48V mild hybrid powertrain and the electrical system pose a major challenge. Current research results show the fundamental potential of optimization-based energy management strategies. However there is a lack of optimization-based solutions that allow online direct control of the electrified air path and the electric motor. In this context, this study presents a nonlinear model predictive control (NMPC) approach for a 48V mild hybrid powertrain with an electric supercharger, which is able to simultaneously improve the response behavior and energy consumption. The control concept is developed on the basis of a detailed system description. The special features of optimization-based control for the degrees of freedom of the powertrain, i.e., the belt starter generator (BSG) and the electrified air path through a throttle, waste gate, and electric supercharger (eC), are addressed. After an analysis and verification of the control properties, the NMPC is evaluated in dynamic driving cycle simulations through a comparison with a state-of-the-art rule-based control strategy. The investigations show that the NMPC is able to control the system well even under transient situations with a high influence of disturbance variables. In addition, the NMPC allows a specific and fuel saving use of the 48V system while improving the driving dynamics at the same time.

PERFORMANCE ANALYSIS OF WASTE GATE VALVE IN REGULATING EXhaust GAS FLOW TOWARDS THE TURBOCHARGER FOR THE FLEXIBLE COMBUSTION PROCESS ON THE TANGGUH JAYA LNG/C SHIP

A turbocharger is an auxiliary engine that functions to supply air into the cylinder and in general every turbocharger has two sides, namely, the compressor side and the turbine side, the rotation of the turbocharger is generated from the remaining exhaust gases from combustion in the cylinder which goes to the turbine side of the turbocharger and produces rotation. on that side and also rotates at the same speed on the compressor side of the turbocharger. The amount of air that will enter the cylinder depends on the rotation of the turbocharger itself, if the rotation of the turbocharger is too fast it will produce too much air in the cylinder which results in knocking or knocking on the main drive engine, whereas if the turbocharger rotates too slowly it will result in too little quantity of air resulting in a misfire or failure of combustion in the cylinder. To determine the rotational speed of the turbocharger, we need a tool that can regulate the quantity of the remaining exhaust gases from combustion in the cylinder, namely the waste gate valve. When the writer carried out the sea practice, the writer experienced various interesting things about the waste gate valve, such as the opening that did not match the degree of the waste gate valve to the difference in the indicator readings on the waste gate valve. In this case the author will analyze the cause of the imperfect supply of air entering the cylinder caused by the non-optimal performance of the waste gate valve.

Co-digestion of sewage sludge and food waste in a wastewater treatment plant based on mainstream anaerobic membrane bioreactor technology: A techno-economic evaluation

The implementation of anaerobic membrane bioreactor as mainstream technology would reduce the load of sidestream anaerobic digesters. This research evaluated the techno-economic implications of co-digesting sewage sludge and food waste in such wastewater treatment plants to optimise the usage of the sludge line infrastructure. Three organic loading rates (1.0, 1.5 and 2.0 kg VS m−3 d−1) and different strategies to manage the additional nutrients backload were considered. Results showed that the higher electricity revenue from co-digesting food waste offsets the additional costs of food waste acceptance infrastructure and biosolids disposal. However, the higher electricity revenue did not offset the additional costs when the nutrients backload was treated in the sidestream (partial-nitritation/anammox and struvite precipitation). Biosolids disposal was identified as the most important gross cost contributor in all the scenarios. Finally, a sensitivity analysis showed that food waste gate fee had a noticeable influence on co-digestion economic feasibility.

Experimental and numerical investigation on the heat transfer of an automotive engine’s turbocharger

Measuring the temperature distribution in a complex and important engine part, such as a turbocharger, is essential for improving engine performance and efficiency. Heat transfer from the turbine to the compressor can strongly influence the turbocharger performance. One of the main measurement methods involves the installation of multiple K-type sensors. However, the location as well as the maximum and minimum temperatures of the turbocharger and the subsequent critical points may not be obtained by using sensors. In the current study, thermocouples, as well as an infra-red camera, are used to study the temperature distribution of the turbocharger housing in a spark ignition engine. A new method is introduced to determine the thermal radiation coefficient of the turbocharger housing by using a laboratory furnace and an infra-red camera. Together with experiments, the finite element method is used to find the temperature distribution in the turbocharger for all thicknesses. Comparing the temperature distribution obtained from simulation with experimental data, an acceptable level of agreement is observed. The location and temperature of the hottest area in experimental and numerical investigations are close to the waste gate. Temperatures using the finite element method for bearings exhibit maximum and minimum errors of 4.9% and 2.3%, respectively, indicating reasonable accuracy for the simulation.

Methodological analysis of variable geometry turbine technology impact on the performance of highly downsized spark-ignition engines

New generation of spark ignition (SI) engines are expected to represent most of the future market share in a context of powertrain hybridization. Nevertheless, the current technology has still critical challenges in front to meet incoming CO2 and pollutant emissions standards, so new technologies are emerging to improve engine efficiency. In parallel to combustion concepts, a key required trend is downsizing based on high engine boosting. New turbocharger technologies, such as variable geometry turbines (VGT), become suitable for its application under the demanding operating conditions of SI engines. In this work, a methodology for the analysis of the VGT usage in comparison with traditional waste-gate (WG) turbine is presented. From experimental data obtained in engine test cell, a theoretical analysis aimed at ensuring full control on turbine boundary conditions, such as combustion variability, compressor map or engine calibration, was conducted. Taking advantage of highly validated and physically representative 1-D gas-dynamics and turbocharger models, the engine performance is discussed as a function of the turbine technology at full and partial load in a wide range of engine speed at the same time as the altitude impact is addressed. In all, it was found that VGT technology shows less limitations in extreme working conditions, such as low- and high-end torque regions, where the WG technology represents a limitation in terms of the maximum power output. Full load differences become more even more evident in altitude working conditions. When it comes to partial loads, differences in fuel consumption are minor, but potentially beneficial for VGTs.

Towards Marine Dual Fuel Engines Digital Twins—Integrated Modelling of Thermodynamic Processes and Control System Functions

This study aims at developing an integrated model that combines detailed engine thermodynamic modelling and the control system functional modelling paving the way towards the development of high-fidelity digital twins. To sufficiently represent the combustion process, a multi-Wiebe function approach was employed, whereas a database for storing the combustion model parameters was developed. The developed model was employed for the systematic investigation of a marine four-stroke dual fuel engine response during demanding transient operation with mode switching and load changes. The derived results were analysed to identify the critical engine components and their effect on the engine operational limitations. The results demonstrate that the developed model can sufficiently represent the engine and its subsystems/components behaviour and effectively capture the engine control system’s functionality. The appropriate turbocharger matching along with the sufficient design of the exhaust gas waste gate valve and fuel control systems are crucial for ensuring the smooth engine operation of dual fuel engines.

An assessment of the impacts of low-pressure exhaust gas recirculation on the air path of a diesel engine equipped with electrically assisted turbochargers

The impact of assisted boosting technologies on the ability to maintain desired exhaust gas recirculation is investigated. Regenerative electrically assisted turbocharging is a promising technique for significantly reducing turbo lag. In addition to mitigating turbo lag, assisted boosting systems also allow fuel economy benefits through reduced pumping losses. Pumping loss reduction is achieved through optimally managing the exhaust pressure via vane position (for a variable geometry turbocharger) or waste gate position (for a waste-gated fixed geometry turbocharger). The consequent loss in exhaust turbine power, from reduced exhaust pressure, is supplemented by electrical assist power. Reduced exhaust pressure and a rapid increase in intake pressure results in a pressure differential across the high-pressure exhaust gas recirculation valve that may not support exhaust gas recirculation flow demands. Hence, a natural trade-off exists between the reduction of pumping loss and the ability to meet exhaust gas recirculation demand, as dictated by prescribed constraints on engine-out emissions. Low-pressure exhaust gas recirculation offers a potential solution that may allow the desired fuel economy improvements without sacrificing the desired exhaust gas recirculation fractions in the intake charge. In this article, we consider this problem and investigate the potential benefits of using low-pressure exhaust gas recirculation for assisted boosted systems.

Development of a New Low-Cost Tandem Variable Geometry Turbocharging Concept for Turbocharger Applications

The air handling system for large diesel/gas engines such as those used on locomotive, marine, and power generation applications require turbochargers with a high reliability and with turbomachinery capable to adjust to different operating conditions and transient requirements. The usage of variable geometry turbocharging (VGT) provides flexibility to the air handling system but adds complexity, cost and reduces the reliability of the turbocharger in exchange for improved engine performance and transient response. For this reason, it was desirable to explore designs that could provide the variability required by the air handling system, without the efficiency penalty of a conventional waste gate and with as little added complexity as possible. The current work describes a new low-cost variable geometry turbine design to address these requirements. The new tandem nozzle concept proposed is applicable to both axial and radial turbines and has been designed using conventional one-dimensional models and two- three-dimensional computational fluid dynamics (CFD) methods. The concept has furthermore been validated experimentally on two different test rigs. In order to avoid the long lead times of procuring castings, the nozzle for the axial turbine was manufactured using new additive manufacturing techniques. Both the axial turbine and the radial turbine designs showed that the concept is capable to achieve a mass flow variability of more than 15% and provide a robust and cost-effective alternative to conventional VGT designs by significantly reducing the number of moveable parts.

Mean Value WGT Diesel Engine Calibration Model for Effective Simulation Research

Recently, to improve vehicle fuel economy, as well as the performance of internal combustion engines, optimized system matching between a vehicle’s drivetrain and engine has become a very important technical issue. For this reason, the need for simulation research on engine and vehicle performance improvement has increased. But in general, since both engine simulation and vehicle simulation require initial engine calibration map input, a simple engine calibration method is required for the efficient configuration of various virtual engine calibration map setups. On this background, in this study, an example of waste gate turbocharger (WGT) cooled — exhaust gas recirculation (EGR) Diesel engine calibration using a test-based mean value engine model is presented as a suitable engine calibration map setting method. Also, the feasibility of an engine calibration model is confirmed through various engine tests. Using the simple model presented here, it is possible for diverse engine operating conditions and engine performance maps to be acquired.

Automotive compressor: effect of an electric throttle in the upstream circuit on the surge limit

On vehicles equipped with a turbocharged engine, there is a risk of compressor surge. This surge generates instabilities that lead to driving inconvenience, or even mechanical failure of the supercharging system. In general, the surge appears rather in transient operation: sudden closing of the throttle valve on gasoline engine, regulation of the EGR on diesel engine linked also to turbine regulation (VNT device or Waste Gate). On a turbocharger test stand, we set up the surge line in a “conventional way”: stationary experiments. Then we set up this line in transient conditions for different positions of an electric throttle placed upstream the compressor. It appears that: the surge limit is pushing back to lower flow rates when it is determined in transient; the surge limit is pushing back to lower flow rates when closing the throttle valve. The tests were carried on by the transient analysis of the surge during a quick closing-opening of the electric throttle valve.

Model Predictive Control of a Diesel Engine with Turbo Compound and Exhaust After-Treatment Constraints

In this work we consider air path control of a Volvo Heavy Duty 13L Diesel engine equipped with three air path actuators Exhaust Gas Recirculation Valve (EGV), Intake Throttle Valve (ITV), turbocharger Wastegate (WG), and a Turbo Compound (TC). The purpose of the TC device is to recover the waste heat energy to improve fuel efficiency. Thus, the motivation is to control the air path system and in particular the exhaust energy to achieve satisfaction of the Exhaust After-Treatment System (EATS) requirements and assess the fuel economy. For this purpose a commercially available industrial tool for Model Predictive Control (MPC) has been applied. The designed controller is integrated in a production Engine Electrical Control Unit (EECU) and tests are performed both in engine test bench and on-road. The results show that by coordination of the air path actuators utilizing advanced MPC framework it leads to improvements in the exhaust energy conversion which was measured by fuel reduction of 0.3% with maintained NOx levels in a World-Harmonized Transient Cycle (WHTC) compared to a Proportional Integral Derivative (PID) control scheme. The designed MPC controller reached mass production maturity level and had a similar margin to the EU6 emission regulation as the compared PID control scheme.

Lower To Mid-Cretaceous Sequence Stratigraphy and Characterization of CO 2 Storage Potential In the Mid-Atlantic U.S. Coastal Plain

Abstract: The Mid-Atlantic U.S. Coastal Plain (New Jersey, Delaware, Maryland, and northern Virginia) contains thick (> 500 m) mid-Cretaceous sand–sandstone reservoirs confined by thick clay–shale confining units and thus has high potential for storage of CO 2 captured from nearby point sources. The predictability of the continuity of the reservoir and confining units can be improved by applying principles of sequence stratigraphy, including integration of lithostratigraphy, biostratigraphy, paleoenvironmental proxies, and a novel application of fluvial aggradation cycles (FACs). We evaluate the storage and confinement potential for the Lower Cretaceous Waste Gate Formation and mid-Cretaceous Potomac Formation/Group in New Jersey and Maryland, which we divide into three major reservoirs (Waste Gate-Potomac Unit I, Potomac Unit II, and Potomac Unit III). We use new core data to ground-truth well-logs and paleoenvironmental changes, sequence stratigraphic stacking patterns (including FACs), and pollen biostratigraphy to update previous well-log correlations in New Jersey and extend these correlations into deep holes in Maryland. While individual sand beds are typically local in extent, zones of sands are broadly correlative over distances of 60 km. These regionally traceable sand-prone zones should be useful for carbon storage. Cenomanian Potomac Unit III sands are relatively thick (∼ 70 m) in New Jersey, but generally thin (average of ∼ 50 m) into Maryland; they are near the updip limit for supercritical storage (800 m) in New Jersey and Maryland and may not be suitable due to updip migration above the supercritical level. Potomac Unit II sands (Albian Pollen Zone II) appear to be discontinuous and less suitable in both states. Potomac Unit I (Aptian Pollen Zone I) and Waste Gate Formation sands (?early Aptian to Berriasian pre-Pollen Zone I) are relatively thick (∼ 88–223 m and ∼ 81–288 m, respectively) and confined in New Jersey and appear to be widespread and continuous; the updip confinement of this reservoir in Maryland is less certain. Volume storage estimates for the Potomac I-Waste Gate in the Mid-Atlantic Coastal Plain are 8.4–33.5 Gt CO 2 , adequate to store CO 2 captured from 24–95 GW of natural gas generation for a century.

Simultaneous dynamic optimization of valves timing and waste gate to improve the load step transient response of a turbocharged spark ignition engine

A result of adding a turbocharger for downsizing of spark ignition engines is slower transient response of the engine in comparison to the naturally aspirated engine. Until recently, it was impossible to use turbocharger in spark ignition engines due to self-ignition problems. However, with the waste gate technology, the turbine speed and hence the boost pressure level are regulated for reduction of self-ignition and increase of torque. In this paper, the engine simulation is done in one-dimensional software GT-POWER and the torque transient response is being focused. For optimization, the coupling between two softwares GT-POWER and MATLAB SIMULINK is used to find an appropriate setting to utilize variable valve timing and waste gate technologies simultaneously during the transient. Variable valve timing in this study refers to opening and closing timings of inlet and exhaust valves. The optimization target is to maximize the torque integral during time interval of the transient. The transient in this paper is the one in which the engine speed is constant and the load increases rapidly and suddenly to a special value (step increase of load). Improved genetic algorithm is used for optimization. With this optimization, the mean improvement percentage in torque integral is about 6.46% for speed 1900 rpm and about 9.33% for speed 2500 rpm. The studied engine is 1.65 L EF7-TC which is a spark ignition engine equipped with turbocharger.

Heat Release Calculation of Internal Combustion Engines by Analyzing the Flame Radiation with Crankshaft Angle Resolution

Improving efficiency and reducing emissions are the principal challenges in developing new generations of internal combustion engines. Different strategies such as downsizing or sophisticated after-treatment of exhaust gases are pursued.Another approach aims at optimizing the parameterization of the engine. Correct adjustments of ignition timings, waste gate position and other factors have significant influence on the combustion process. A multitude of application data is generated during the development process to predefine appropriate settings for most situations. Improvements in regards to the application effort and the quality of the settings can be achieved by measuring the combustion process and optimizing the parametrization in a closed loop. However, cylinder pressure sensors that are used during the development process are too expensive for series applications.This paper focuses on an affordable combustion sensor based on the measurement of the electromagnetic radiation of the combustion flame.The intensity of electromagnetic radiation by chemiluminescence is a good indicator for the status of the combustion as it is primarily dependent on the number of excited molecules. A characteristic spectral band is emitted by the OH radical, which is created in the flame front and corresponds to the number of reactants that are burned.A research engine was equipped with an access for an optical measurement system for chemiluminescence and light emission in general. To achieve sufficient amplification and temporal bandwidth, a special detector circuitry was designed.The measurement data was used to analyze the quality of different light emission signals and to investigate their qualification for heat release calculations.

Analysis of the backpressure effect of an Organic Rankine Cycle (ORC) evaporator on the exhaust line of a turbocharged heavy duty diesel power generator for marine applications

In marine and power generation sectors, waste heat recovery technologies are attracting growing attention in order to increase heavy duty diesel engines efficiency and decrease fuel consumption, with the purpose of respecting stringent emissions legislations.In this work, the backpressure effect of an Organic Rankine Cycle (ORC) evaporator on the exhaust line of a turbocharged, V12 heavy duty diesel engine, for typical marine and power generation applications has been investigated using the commercial software Ricardo WAVE. Three different state-of-the art turbocharging strategies are assessed in order to counterbalance the increased pumping losses of the engine due to the boiler installation: fixed turbine, Waste-Gate (WG) and Variable Geometry Turbine (VGT). At the same time, the steady-state thermodynamic performance of two different ORC configurations, simple tail-pipe evaporator and recuperated simple tail-pipe evaporator layouts, are assessed, with the scope of further increasing the engine power output, recovering unutilized exhaust gas heat. Several different working fluids, suitable for medium-high temperature waste heat recovery, are evaluated and screened, considering, as well, health and safety issues. Thermodynamic cycle parameters such as, for example, evaporation and condensing pressures, working fluid mass flow and cycle temperatures, are optimized in order to obtain the maximum improvement in Brake Specific Fuel Consumption (bsfc).From the engine side point of view, a VGT turbocharger is the most favorable solution to withstand increased backpressure, while, regarding the ORC side, between the considered fluids and layouts, acetone and a recuperated cycle show the most promising performance.