175 research outputs found

    Optimising the energy efficiency and transient response of diesel engines through an electric turbocharger

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    The electric turbocharger provides great potential for vehicle fuel efficiency improvement, exhaust emissions reduction and transient response acceleration. It makes the engine runs as a hybrid system so critical challenges are raised in energy management and control. This paper proposes a realtime energy management strategy for the electric turbocharger. A multi-variable explicit model predictive controller is designed to regulate the key variables in the engine air system, while the optimal setpoints of those variables are generated by a high level controller. The controllers work in a highly efficient way to achieve the optimal energy management. This strategy has been validated in simulations and experiments. Excellent tracking performance and high robustness demonstrate the effectiveness of the proposed method

    Optimization of engine air path with hybrid boosting systems

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    14th International Conference on Turbochargers and Turbocharging

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    14th International Conference on Turbochargers and Turbocharging addresses current and novel turbocharging system choices and components with a renewed emphasis to address the challenges posed by emission regulations and market trends. The contributions focus on the development of air management solutions and waste heat recovery ideas to support thermal propulsion systems leading to high thermal efficiency and low exhaust emissions. These can be in the form of internal combustion engines or other propulsion technologies (eg. Fuel cell) in both direct drive and hybridised configuration. 14th International Conference on Turbochargers and Turbocharging also provides a particular focus on turbochargers, superchargers, waste heat recovery turbines and related air managements components in both electrical and mechanical forms

    Analysis of two stroke marine diesel engine operation including turbocharger cut-out by using a zero-dimensional model

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    In this article, the operation of a large two-stroke marine diesel engine including various cases with turbocharger cut-out was thoroughly investigated by using a modular zero-dimensional engine model built in MATLAB/Simulink environment. The model was developed by using as a basis an in-house modular mean value engine model, in which the existing cylinder block was replaced by a more detailed one that is capable of representing the scavenging ports-cylinder-exhaust valve processes. Simulation of the engine operation at steady state conditions was performed and the derived engine performance parameters were compared with the respective values obtained by the engine shop trials. The investigation of engine operation under turbocharger cut-out conditions in the region from 10% to 50% load was carried out and the influence of turbocharger cut-out on engine performance including the in-cylinder parameters was comprehensively studied. The recommended schedule for the combination of the turbocharger cut-out and blower activation was discussed for the engine operation under part load conditions. Finally, the influence of engine operating strategies on the annual fuel savings, CO2 emissions reduction and blower operating hours for a Panamax container ship operating at slow steaming conditions is presented and discussed

    Turbo-Discharging the internal combustion engine

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    This thesis reports original research on a novel internal combustion (IC) engine charge air system concept called Turbo-Discharging. Turbo-Discharging depressurises the IC engine exhaust system so that the engine gas exchange pumping work is reduced, thereby reducing fuel consumption and CO2 emissions. There is growing concern regarding the human impact on the climate, part of which is attributable to motor vehicles and transport. Recent legislation has led manufacturers to improve the fuel economy and thus reduce the quantity of CO2 generated by their vehicles. As this legislation becomes more stringent manufacturers are looking to new and developing technologies to help further improve the fuel conversion efficiency of their vehicles. Turbo-Discharging is such a technology which benefits from the fact it uses commonly available engine components in a novel system arrangement. Thermodynamic and one-dimensional gas dynamics models and experimental testing on a 1.4 litre four cylinder four-stroke spark ignition gasoline passenger car engine have shown Turbo-Discharging to be an engine fuel conversion efficiency and performance enhancing technology. This is due to the reduction in pumping work through decreased exhaust system pressure, and the improved gas exchange process resulting in reduced residual gas fraction. Due to these benefits, engine fuel conversion efficiency improvements of up to 4% have been measured and increased fuel conversion efficiency can be realised over the majority of the engine operating speed and load map. This investigation also identified a measured improvement in engine torque over the whole engine speed range with a peak increase of 12%. Modelling studies identified that both fuel conversion efficiency and torque can be improved further by optimisation of the Turbo-Discharging system hardware beyond the limitations of the experimental engine test. The model predicted brake specific fuel consumption improvements of up to 16% at peak engine load compared to the engine in naturally aspirated form, and this increased to up to 24% when constraints imposed on the experimental engine test were removed

    A novel framework for enhancing marine dual fuel engines environmental and safety performance via digital twins

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    The Internet of Things (IoT) advent and digitalisation has enabled the effective application of the digital twins (DT) in various industries, including shipping, with expected benefits on the systems safety, efficiency and environmental footprint. The present research study establishes a novel framework that aims to optimise the marine DF engines performance-emissions trade-offs and enhance their safety, whilst delineating the involved interactions and their effect on the performance and safety. The framework employs a DT, which integrates a thermodynamic engine model along with control function and safety systems modelling. The DT was developed in GT-ISE© environment. Both the gas and diesel operating modes are investigated under steady state and transient conditions. The engine layout is modified to include Exhaust Gas Recirculation (EGR) and Air Bypass (ABP) systems for ensuring compliance with ‘Tier III’ emissions requirements. The optimal DF engine settings as well as the EGR/ABP systems settings for optimal engine efficiency and reduced emissions are identified in both gas and diesel modes, by employing a combination of optimisation techniques including multi-objective genetic algorithms (MOGA) and Design of Experiments (DoE) parametric runs. This study addresses safety by developing an intelligent engine monitoring and advanced faults/failure diagnostics systems, which evaluates the sensors measurements uncertainty. A Failure Mode Effects and Analysis (FMEA) is employed to identify the engine safety critical components, which are used to specify operating scenarios for detailed investigation with the developed DT. The integrated DT is further expanded, by establishing a Faulty Operation Simulator (FOS) to simulate the FMEA scenarios and assess the engine safety implications. Furthermore, an Engine Diagnostics System (EDS) is developed, which offers intelligent engine monitoring, advanced diagnostics and profound corrective actions. This is accomplished by developing and employing a Data-Driven (DD) model based on Neural Networks (NN), along with logic controls, all incorporated in the EDS. Lastly, the manufacturer’s and proposed engine control systems are combined to form an innovative Unified Digital System (UDS), which is also included in the DT. The analysis of marine (DF) engines with the use of an innovative DT, as presented herein, is paving the way towards smart shipping.The Internet of Things (IoT) advent and digitalisation has enabled the effective application of the digital twins (DT) in various industries, including shipping, with expected benefits on the systems safety, efficiency and environmental footprint. The present research study establishes a novel framework that aims to optimise the marine DF engines performance-emissions trade-offs and enhance their safety, whilst delineating the involved interactions and their effect on the performance and safety. The framework employs a DT, which integrates a thermodynamic engine model along with control function and safety systems modelling. The DT was developed in GT-ISE© environment. Both the gas and diesel operating modes are investigated under steady state and transient conditions. The engine layout is modified to include Exhaust Gas Recirculation (EGR) and Air Bypass (ABP) systems for ensuring compliance with ‘Tier III’ emissions requirements. The optimal DF engine settings as well as the EGR/ABP systems settings for optimal engine efficiency and reduced emissions are identified in both gas and diesel modes, by employing a combination of optimisation techniques including multi-objective genetic algorithms (MOGA) and Design of Experiments (DoE) parametric runs. This study addresses safety by developing an intelligent engine monitoring and advanced faults/failure diagnostics systems, which evaluates the sensors measurements uncertainty. A Failure Mode Effects and Analysis (FMEA) is employed to identify the engine safety critical components, which are used to specify operating scenarios for detailed investigation with the developed DT. The integrated DT is further expanded, by establishing a Faulty Operation Simulator (FOS) to simulate the FMEA scenarios and assess the engine safety implications. Furthermore, an Engine Diagnostics System (EDS) is developed, which offers intelligent engine monitoring, advanced diagnostics and profound corrective actions. This is accomplished by developing and employing a Data-Driven (DD) model based on Neural Networks (NN), along with logic controls, all incorporated in the EDS. Lastly, the manufacturer’s and proposed engine control systems are combined to form an innovative Unified Digital System (UDS), which is also included in the DT. The analysis of marine (DF) engines with the use of an innovative DT, as presented herein, is paving the way towards smart shipping

    Air induction noise investigation during turbocharger surge events in petrol engines

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    Turbocharging is used as a means to downsize petrol engines, thereby, producing more power for a lower engine size, when compared with a naturally aspirated engine. Due to the presence of a throttle valve in the intake system in petrol engines, flow is restricted at the outlet pipe of the compressor during low load engine operation. For example, during transient tip out tip in maneuvers. Hence, there is a chance of the turbocharger operating in near surge or surge conditions and, thus, generating surge noise. This Thesis describes an experimental and simulation method to predict and measure the turbocharger surge noise. Initially, experimental transient tip-in and tip-out maneuver was performed on a non turbocharged car with a petrol engine. The measured noise level in the intake manifold, at a low frequency of up to 1200 Hz, was analysed and was shown not to represent surge noise. Next, a one dimensional simulation method was applied to simulate the noise of the engine and this demonstrated an increase in the acoustic pressure level in the intake manifold during the tip in and tip out maneuver. However, a surge noise pattern was not observed in the analysis of acoustic pressure signals in the intake system using Short Time Fourier Transform (STFT). The simulation procedure was also used to inform the design of an experimental rig to recreate the surge noise under laboratory conditions. An experimental turbocharger noise rig, designed and built for this purpose, is explained in the Thesis. Important component parts likely to be involved in the surge noise generation such as the intake system, compressor, throttle body, compressor recirculation valve and measurement and control systems were integrated into the test rig. Background noise contributions from the electric motor, AC mains, supercharger pulley, throttle body, inverter fan, throttle body gearing and structural vibration of the supporting structure were identified from the analysed frequency components of the signals from surface microphone measurements taken at the intake system. This helped to clearly identify the surge noise frequency components (3250 Hz) in the STFT analysis. The fundamental mechanism of noise generation was identified using an analysis of the experimental results and a frequency calculation for vortex shedding and the radial acoustic resonances. One of the main conclusions of the Thesis is that the compressor recirculation valve (CRV) open or close position, the CRV delay time and the throttle position are major contributing factors to the cause of the surge noise. Another major conclusion is that the radial acoustic resonance may be a mechanism of surge noise generation. Finally, a passive solution to reduce the surge noise is proposed. A pipe with cross ribs is designed as a passive solution using the radial acoustic resonance calculation and the corresponding nodal patterns. This solution demonstrated a measured intake system noise reduction of up to 10dB under compressor surge conditions

    Total pressure loss mechanism in a diesel engine turbocharger

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    Simulation tools are intensively used in the design stage of diesel engines due to their contributions to significant savings in cost and time for the engine development. Since most of DI diesel engines are turbocharged, it is of vital importance to hold a good understanding of turbine and compressor characteristic to predict the engine performance accurately. However, this data is often not available from turbocharger manufacturers, particularly for turbines. On available turbine maps the operating range of the turbine is constrained due to limitations of conventional turbocharger test benches. Operations with a wider range of turbocharger pressure ratios can be achieved by employing complex turbocharger test benches, which will also lead to higher costs including hardware and labour. An alternative solution is to develop numerical models for the turbocharger based on thermodynamics. In this thesis numerical models has been developed for predicting the performance of both the centrifugal compressors and turbines and they have been also validated using test cases, particularly for variable geometry turbines. Following detailed parametric studies, the turbocharger model has been validated against experimental data of a turbocharger with a variable geometry turbine. Results showed that the model was capable of predicting the characteristics maps of the turbocharger accurately, requiring a minimal amount of turbocharger geometric properties, experimental data and calibration parameters. Thus, by combing with the engine performance simulation software there is a highly potential for the numerical model developed in this work to become a useful tool for predicting engine performance and turbo matching calculations or diagnostic applications

    Low Temperature Waste Heat Recovery in Internal Combustion Engines

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    Over the past few decades, the automotive industry has increasingly looked towards increasing the efficiency of the internal combustion engine to meet more stringent emission norms and as a measure to meet demands for improved air quality in cities. One method to improve the internal combustion engine efficiency is to recover some of the energy lost to the coolant and the exhaust using a secondary thermodynamic cycle such as an Organic Rankine Cycle. Organic Rankine Cycle systems have been shown to be some of the most efficient systems for waste heat recovery in automotive applications.While most research into Organic Rankine Cycle waste heat recovery systems studies the recovery of heat rejected to the exhaust gases, the coolant represents a large source of waste heat which is largely overlooked. This is because of the lower temperature of the coolant in comparison to the exhaust gases, which means a lower quality of energy and hence, lower recoverable power from the system.This thesis aims to investigate methods to increase the energy quality for low temperature waste heat in the engine and optimise the waste heat recovery system to improve the recoverable power and powertrain efficiency. The work done was a combination of experiments and simulations. The engines studied were primarily the Scania D13 heavy duty engine, both in single cylinder and multi cylinder configurations, and the Volvo D4 light duty engine.The thesis first numerically investigates the use of elevated coolant temperatures for a single cylinder Scania D13 engine to increase the recoverable power from the engine waste heat. The system simulated used two separate recovery loops for the recovery of waste heat from the exhaust gases and the coolant with ethanol as the working fluid. It was seen that there exists an optimum coolant temperature, depending on engine operating conditions, to maximise recoverable power from the coolant. On the other hand, the recoverable power from the exhaust increased consistently with increasing coolant temperatures due to higher exhaust gas temperatures. The gross indicated efficiency and the combustion were seen to be largely unaffected by the coolant temperature in the study.The thesis then studies the use of an integrated waste heat recovery cooling circuit using simulations for the multi-cylinder Scania D13 engine. This is where the coolant is also used as the working fluid in the Organic Rankine Cycle and the engine cooling channels act as a part of the evaporator. Here, a significant increase in system gross indicated efficiency was seen with the use of evaporative cooling. On comparison, while the integrated waste heat recovery system was seen to perform better than using a dual loop Rankine cycle system with elevated coolant temperatures, there is also increased mechanical complexity in implementing such a system, which lowers its viability for application.The next study uses experimental data from the Volvo D4 light duty engine to optimise the waste heat recovery process for different operating points. An expansive study of working fluids was done to see the fluids that could recover the maximum power from the different waste heat sources. It was seen that for the low temperature heat, cyclopentane performed the best, whereas for high temperature heat, methanol and acetone were the best performing working fluids. An analysis of the working fluids showed that this was due to a combination of thermodynamic properties of these fluids and the constraints imposed for the simulations. The system brake efficiency was increased by 5.2 percentage points when using heat from both the exhaust gases and the coolant. From this, the increase in brake efficiency solely as the effect of increasing the coolant temperature was 1.7 percentage points.Finally, the thesis evaluates the use of an optimised coolant temperature strategy to see the reduction in fuel consumption over a standard World Harmonized Transient Cycle for the multi-cylinder Scania D13 engine. It was seen that cyclopentane and methanol, again, performed the best, showing a total potential reduction of 9% in fuel consumption over the cycle.This thesis thus gives insights on the optimisation process of implementing low temperature waste heat recovery systems for internal combustion engines and improving the powertrain efficiency
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