Publications
243 results found
Hu B, Copeland C, Brace C, et al., 2014, A New Turboexpansion Concept in a Twin-Charged Engine System
Engines equipped with pressure charging systems are more prone to knock partly due the increased intake temperature. Meanwhile, turbocharged engines when operating at high engine speeds and loads cannot fully utilize the exhaust energy as the wastegate is opened to prevent overboost. The turboexpansion concept thus is conceived to reduce the intake temperature by utilizing some otherwise unexploited exhaust energy. This concept can be applied to any turbocharged engines equipped with both a compressor and a turbine-like expander on the intake loop. The turbocharging system is designed to achieve maximum utilization of the exhaust energy, from which the intake charge is over-boosted. After the intercooler, the turbine-like expander expands the over-compressed intake charge to the required plenum pressure and reduces its temperature whilst recovering some energy through the connection to the crankshaft. It is anticipated that such a concept has benefits for knock resistance and energy recovery despite suffering higher pumping losses. This paper, for the first time, will investigate the net fuel efficiency benefit from this concept using a super-turbo twin-charger 1-D simulation model. By the operation of a switch between compressor and expander mode, the supercharger could provide boost at low engine speed whilst behaving like a turbine presenting an indirect means to recover exhaust gas energy at high engine speed and meanwhile reducing the intake temperature. The results showed that the BSFC improvement depended on the efficiency of the supercharger as an expander.
Offer GJ, Plant DJ, Silversides RW, et al., 2014, Control and energy management strategies for a novel series hybrid
In this work a novel series hybrid powertrain concept is presented. The concept removes the requirement for a power electronic converter to manage the state of charge of the accumulators by controlling the power flow between the generator and accumulator. Instead, the engine and generator are directly coupled and the state of charge of the accumulators is maintained by controlling the speed and power output of the engine to control the power flow to the accumulators. Results are presented from a proof-of-concept system that was built for a vehicle with a target peak power of 60kW with supercapacitors. Models are also presented comparing and contrasting a battery version with the supercapacitor version for a Formula Student vehicle. The powertrain is particularly suited for applications which have very high torque requirements, and hence the use of a mechanical gearbox introduces significant cost & weight, and is also ideally suited for applications where power needs to be distributed throughout an application to multiple locations, and hence multiple mechanical linkages would normally be required. The supercapacitor version is most suited to applications with high peak to average load ratios and noisy load cycles, and the battery version could be seen as a low cost route to range extend a battery electric vehicle.
Hey J, Teo TJ, Viet PB, et al., 2014, Electromagnetic actuator design analysis using a two-stage optimization method with coarse-fine model output space mapping, IEEE Transactions on Industrial Electronics, Vol: 61, Pages: 5453-5464, ISSN: 0278-0046
Electromagnetic actuators are energy conversion devices that suffer from inefficiencies. The conversion losses generate internal heat, which is undesirable, as it leads to thermal loading on the device. Temperature rise should be limited to enhance the reliability, minimize thermal disturbance, and improve the output performance of the device. This paper presents the application of an optimization method to determine the geometric configuration of a flexure-based linear electromagnetic actuator that maximizes output force per unit of heat generated. A two-stage optimization method is used to search for a global solution, followed by a feasible solution locally using a branch and bound method. The finite element magnetic (fine) model is replaced by an analytical (coarse) model during optimization using an output space mapping technique. An 80% reduction in computation time is achieved by the application of such an approximation technique. The measured output from the new prototype based on the optimal design shows a 45% increase in air gap magnetic flux density, a 40% increase in output force, and a 26% reduction in heat generation when compared with the initial design before application of the optimization method.
Hey J, Kiew CM, Yang G, et al., 2014, Model-Based Compensation of Thermal Disturbance in a Precision Linear Electromagnetic Actuator, IEEE-ASME TRANSACTIONS ON MECHATRONICS, Vol: 19, Pages: 1477-1488, ISSN: 1083-4435
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- Citations: 9
Hey J, Malloy AM, Martinez-Botas R, et al., 2014, Experimentally determined thermal parameters of an energy conversion device using a constraint least square parameter estimation method coupled with an analytical thermal model, 15th International Heat Transfer Conference, Publisher: Begell House Inc. Publishers
Energy conversion device suffer from thermal loading as a result of inefficiencies during their operation which may lead to device degradation and possible failure. It is of interest to monitor the internal temperature of the device to ensure its safe operation. Mathematical models of different complexities have been developed for the purpose of real time temperature monitoring. Temperature estimation accuracy is dependent on the thermal parameters such as the material conductivities and convective heat transfer coefficients. The complex construction of such devices means that the exact value of the thermal parameters is often not known. This paper presents the use of an inverse identification technique for the estimation of thermal parameters of an axial flux permanent magnet device designed for vehicular applications. The proposed method provides a practical approach to determine the thermal parameters indirectly from temperature measurements. A constraint least square method coupled to an analytical solution of the one step ahead predictor of temperature is used for parameter estimation. A parametric study is performed and it is shown that some of these parameters vary as a function of the operating point of the device. The estimated parameters are then used in an analytical thermal model for real time temperature monitoring during a drive cycle. A maximum time averaged error of 1.8 deg C or an equivalent error of about 3% of the measurement range is observed for the estimated winding temperature.
Rajoo S, Romagnoli A, Martinez-Botas R, et al., 2014, Automotive exhaust power and waste heat recovery technologies, Automotive Exhaust Emissions and Energy Recovery, Pages: 265-281, ISBN: 9781633214934
Internal combustion engines (ICE) almost entirely responsible to power the land and sea transportation needs for the past many decades. Amid the increasing awareness on environmental impact and volatility of fossil fuel dependence, internal combustion engines are envisioned to dominate way into the future. Looking ahead to the year 2020, many new technologies which encompass alternative engines and fuels may have increasing share of the transportation and industrial markets, however major proportion of prime movers will be powered by advanced internal combustion engines. The United States Department of Energy (DOE) stated that improving the efficiency of internal combustion engines is the most promising and cost-effective approach to increasing fuel economy of vehicle over the next 30 years. They put forward the targeted efficiency improvement of 25-40% and 20% for passenger and commercial vehicles respectively. Tackling the waste heat of exhaust gas will be one of the most significant technological efforts in achieving the required tall order efficiency improvements. Approximately 20 - 45% of the fuel energy into an internal combustion engine is wasted in the exhaust, which could be enhanced for system level efficiency improvement. DOE hasdemonstrated via a 2nd law estimate for exhaust gas recovery systems, that, peak brake thermal efficiency of a 1.9L diesel engine can be pushed from 41% to 44.5% - 53.6%, an improvement of approximately 8.5% - 30.7%. Thus, exhaust waste heat recovery holds great potential of improvement in engine brake thermal efficiency. There are some key technologies which have been tested and proven to recover exhaust heat and turn it into useful energy such as electricity. These are, among others, Thermoelectric Generator (TEG), Bottoming cycles and Turbocompounding (TC). The main objective of this chapter is to critically review available waste heat recovery technologies based on latest developments, research trends and economic feasibility.
Cao T, Xu L, Yang M, et al., 2014, Radial Turbine Rotor Response to Pulsating Inlet Flows, JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME, Vol: 136, ISSN: 0889-504X
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- Citations: 24
Newton P, Romagnoli A, Martinez-Botas R, et al., 2014, A Method of Map Extrapolation for Unequal and Partial Admission in a Double Entry Turbine, JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME, Vol: 136, ISSN: 0889-504X
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- Citations: 9
Wu B, Parkes MP, Yufit V, et al., 2014, Design and testing of a 9.5 kWe proton exchange membrane fuel cell-supercapacitor passive hybrid system, International Journal of Hydrogen Energy, Vol: 39, Pages: 7885-7896, ISSN: 0360-3199
The design and test of a 9.5 kWe proton exchange membrane fuel cell passively coupled with a 33 × 1500 F supercapacitor pack is presented. Experimental results showed that the system reduced dynamic loads on the fuel cell without the need for additional DC/DC converters. Fuel efficiency gains of approximately 5% were achieved by passive hybridisation in addition to addressing two main operational degradation mechanisms: no-load idling and rapid load cycling.Electrochemical Impedance Spectroscopy measurements indicated that the supercapacitor capacitance dropped with decreasing cell voltage and suggested that operation below 1.3 V is not recommended. Knee-frequency measurements suggested little benefit was gained in using passive systems with load cycles that have frequency components above 0.19 Hz. Analysis of system sizing suggested using the minimum number of supercapacitors to match the open circuit voltage of the fuel cell to maximise load buffering.
Padzillah MH, Rajoo S, Martinez-Botas RF, 2014, Influence of speed and frequency towards the automotive turbocharger turbine performance under pulsating flow conditions, ENERGY CONVERSION AND MANAGEMENT, Vol: 80, Pages: 416-428, ISSN: 0196-8904
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- Citations: 40
Terdich N, Martinez-Botas RF, Romagnoli A, et al., 2014, Mild Hybridization via Electrification of the Air System: Electrically Assisted and Variable Geometry Turbocharging Impact on an Off-Road Diesel Engine, JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME, Vol: 136, ISSN: 0742-4795
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- Citations: 25
Rajoo S, Pesiridis A, Martinez-Botas R, 2014, Novel method to improve engine exhaust energy extraction with active control turbocharger, INTERNATIONAL JOURNAL OF ENGINE RESEARCH, Vol: 15, Pages: 236-249, ISSN: 1468-0874
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- Citations: 8
Romagnoli A, Martinez-Botas RF, Bin Mamat AMI, et al., 2014, Modelling and simulation of a turbogenerator for energy recovery
Market trends for increased specific engine power and more electrical energy on the powergrid indicated that 3kW+ is not unrealistic, and, along with customer demands for fuel consumption improvements and emissions reduction, are driving requirements for the electrification of components, including turbochargers. The objective of the study was to understand how much energy could be recovered from an existing GTDI (Gasoline Turbocharged Direct Injection) engine for such a device. GTDI engines waste significant exhaust enthalpy, since even at moderate loads the WG (wastegate) starts to open. This effect is required to reduce EBP (Exhaust Back Pressure). Another factor is catalyst overheating protection and lambda enrichment is used to perform this. Normally the catalyst is placed downstream of the turbine. However, the turbine has a temperature drop across it when used for energy recovery. Since catalyst performance is critical for emissions, the only reasonable package location for an additional device is downstream of it. This is a challenge for any additional energy recovery, but a smaller LPT (Low Pressure Turbine) is a design requirement, optimised to operate at lower turbine pressure ratios. A WAVE model of the GTDI engine was adapted to include a TG (Turbogenerator) and bypass throttle (WG) with the TG in mechanical turbocompounding configuration, and calibrated with steady state dynamometer data in order to estimate drive cycle benefit using a KP (Key Point) analysis. This includes power and fuel consumption. A further sensitivity analysis on a higher engine speed indicates that significant energy recovery can be achieved.
Mamat AMI, Romagnoli A, Martinez-Botas RF, 2014, Characterisation of a low pressure turbine for turbocompounding applications in a heavily downsized mild-hybrid gasoline engine, ENERGY, Vol: 64, Pages: 3-16, ISSN: 0360-5442
Hey J, Malloy A, Martinez-Botas R, et al., 2014, Experimentally determined thermal parameters of an energy conversion device using a constraint least square parameter estimation method coupled with an analytical thermal model
Energy conversion device suffer from thermal loading as a result of inefficiencies during their operation which may lead to device degradation and possible failure. It is of interest to monitor the internal temperature of the device to ensure its safe operation. Mathematical models of different complexities have been developed for the purpose of real time temperature monitoring. Temperature estimation accuracy is dependent on the thermal parameters such as the material conductivities and convective heat transfer coefficients. The complex construction of such devices means that the exact value of the thermal parameters is often not known. This paper presents the use of an inverse identification technique for the estimation of thermal parameters of an axial flux permanent magnet device designed for vehicular applications. The proposed method provides a practical approach to determine the thermal parameters indirectly from temperature measurements. A constraint least square method coupled to an analytical solution of the one step ahead predictor of temperature is used for parameter estimation. A parametric study is performed and it is shown that some of these parameters vary as a function of the operating point of the device. The estimated parameters are then used in an analytical thermal model for real time temperature monitoring during a drive cycle. A maximum time averaged error of 1.8°C or an equivalent error of about 3% of the measurement range is observed for the estimated winding temperature.
Turner JWG, Popplewell A, Patel R, et al., 2014, Ultra Boost for Economy: Extending the Limits of Extreme Engine Downsizing, SAE International Journal of Engines, Vol: 7, Pages: 387-417, ISSN: 1946-3936
The paper discusses the concept, design and final results from the 'Ultra Boost for Economy' collaborative project, which was part-funded by the Technology Strategy Board, the UK's innovation agency. The project comprised industry- and academia-wide expertise to demonstrate that it is possible to reduce engine capacity by 60% and still achieve the torque curve of a modern, large-capacity naturally-aspirated engine, while encompassing the attributes necessary to employ such a concept in premium vehicles. In addition to achieving the torque curve of the Jaguar Land Rover naturally-aspirated 5.0 litre V8 engine (which included generating 25 bar BMEP at 1000 rpm), the main project target was to show that such a downsized engine could, in itself, provide a major proportion of a route towards a 35% reduction in vehicle tailpipe CO2 on the New European Drive Cycle, together with some vehicle-based modifications and the assumption of stop-start technology being used instead of hybridization. In order to do this vehicle modelling was employed to set part-load operating points representative of a target vehicle and to provide weighting factors for those points. The engine was sized by using the fuel consumption improvement targets and a series of specification steps designed to ensure that the required full-load performance and driveability could be achieved. The engine was designed in parallel with 1-D modelling which helped to combine the various technology packages of the project, including the specification of an advanced charging system and the provision of the necessary variability in the valvetrain system. An advanced intake port was designed in order to ensure the necessary flow rate and the charge motion to provide fuel mixing and help suppress knock, and was subjected to a full transient CFD analysis. A new engine management system was provided which necessarily had to be capable of controlling many functions, including a supercharger engagement clutch and full bypa
Romagnoli A, Wan-Salim WS, Gurunathan BA, et al., 2014, Assessment of supercharging boosting component for heavily downsized gasoline engines, 11th International Conference on Turbochargers and Turbocharging, Publisher: WOODHEAD PUBL LTD, Pages: 13-+
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- Citations: 9
Yang MY, Padzillah MH, Zhuge WL, et al., 2014, Comparison of the influence of unsteadiness between nozzled and nozzleless mixed flow turbocharger turbine\, 11th International Conference on Turbochargers and Turbocharging, Publisher: WOODHEAD PUBL LTD, Pages: 333-+
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- Citations: 5
Xenos DP, Cicciotti M, Bouaswaig AEF, et al., 2014, MODELING AND OPTIMIZATION OF INDUSTRIAL CENTRIFUGAL COMPRESSOR STATIONS EMPLOYING DATA-DRIVEN METHODS, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
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- Citations: 2
Cicciotti M, Bouaswaiga AEF, Martinez-Botas RF, et al., 2014, Simultaneous Nonlinear Reconciliation and Update of Parameters for Online Use of First-Principles Models: An Industrial Case-Study on Compressors, 24th European Conference on Computer Aided Process Engineering (ESCAPE 24), Pages: 457-462, ISSN: 1570-7946
Online uses of first-principles models include nonlinear model predictive control, softsensors, real-time optimization, and real-time process monitoring, among others. The industrial implementation of these applications needs accurate adaptive models and reconciled data. The simultaneous reconciliation and update of parameters of a first- principles model can be achieved using an optimization framework that exploits physical and analytical redundancy of information. This paper demonstrates this concept by means of an industrial case-study. The case-study is a multi-stage centrifugal compressor for which a first-principles model was recently developed. The update of the model parameters is necessary to capture slowly progressing mechanical degradation (e.g. due to fouling and erosion). The reconciliation of the data is necessary for reducing downtime of the online model-based applications caused by gross errors. Two industrial cases including sensor failures were analysed. Applying the proposed framework, it was possible to reconcile the measurements for both cases. © 2014 Elsevier B.V.
Cicciotti M, Xenos DP, Bouaswaig AEF, et al., 2014, ONLINE PERFORMANCE MONITORING OF INDUSTRIAL COMPRESSORS USING MEANLINE MODELLING, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
Newton P, Martinez-Botas R, Seiler M, 2014, A 3-DIMENSIONAL COMPUTATIONAL STUDY OF PULSATING FLOW INSIDE A DOUBLE ENTRY TURBINE, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
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- Citations: 2
Padzillah MH, Yang M, Zhuge W, et al., 2014, NUMERICAL AND EXPERIMENTAL INVESTIGATION OF PULSATING FLOW EFFECT ON A NOZZLED AND NOZZLELESS MIXED FLOW TURBINE FOR AN AUTOMOTIVE TURBOCHARGER, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
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- Citations: 5
Yang M, Martinez-Botas R, Rajoo S, et al., 2014, INFLUENCE OF VOLUTE CROSS-SECTIONAL SHAPE OF A NOZZLELESS TURBOCHARGER TURBINE UNDER PULSATING FLOW CONDITIONS, ASME Turbo Expo: Turbine Technical Conference and Exposition, Publisher: AMER SOC MECHANICAL ENGINEERS
Sakai M, Romagnoli A, Martinez-Botas RF, 2014, Performance and flow-field assessment of an EGR pulse optimised asymmetric double-entry turbocharger turbine, 11th International Conference on Turbochargers and Turbocharging, Publisher: WOODHEAD PUBL LTD, Pages: 321-+
Wu B, Yufit V, Marinescu M, et al., 2013, Coupled thermal–electrochemical modelling of uneven heat generation in lithium-ion battery packs, Journal of Power Sources, Vol: 243, Pages: 544-554, ISSN: 0378-7753
Abstract In battery packs with cells in parallel, the inter-cell connection resistances can cause unequal loads due to non-uniform interconnect overpotentials and consequentially lead to non-uniform heating. This article explores how load imbalances are generated in automotive applications, by describing a battery pack with finite interconnect resistances. Each cell inside the pack is represented by a pseudo 2D electrochemical model coupled with a lumped thermal model. Increasing the number of cells in parallel results in a linear increase in load non-uniformity, whilst increasing the ratio of interconnect to battery impedance results in a logarithmic increase in load non-uniformity, with cells closest to the load points experiencing the largest currents. Therefore, interconnect resistances of the order of mΩ can have a significant detrimental impact. Under steady state discharge the cell impedance changes until the loads balance. This process, however, can take hundreds of seconds and therefore may never happen under dynamic load cycles. Cycling within a narrow state-of-charge range and pulse loading are shown to be the most detrimental situations. Upon load removal, re-balancing can occur causing further heating. Simulation of a 12P7S pack under a real world load cycle shows that these effects could cause localised thermal runaway.
Lorf C, Martinez-Botas RF, Howey DA, et al., 2013, Comparative analysis of the energy consumption and CO<sub>2</sub> emissions of 40 electric, plug-in hybrid electric, hybrid electric and internal combustion engine vehicles, TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIRONMENT, Vol: 23, Pages: 12-19, ISSN: 1361-9209
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- Citations: 45
Offer GJ, Plant DJ, Silversides RW, et al., 2013, Control and energy management strategies for a novel series hybrid, World Electric Vehicle Journal, Vol: 6, Pages: 288-297, ISSN: 2032-6653
In this work a novel series hybrid powertrain concept is presented. The concept removes the requirement for a power electronic converter to manage the state of charge of the accumulators by controlling the power flow between the generator and accumulator. Instead, the engine and generator are directly coupled and the state of charge of the accumulators is maintained by controlling the speed and power output of the engine to control the power flow to the accumulators. Results are presented from a proof-of-concept system that was built for a vehicle with a target peak power of 60kW with supercapacitors. Models are also presented comparing and contrasting a battery version with the supercapacitor version for a Formula Student vehicle. The powertrain is particularly suited for applications which have very high torque requirements, and hence the use of a mechanical gearbox introduces significant cost & weight, and is also ideally suited for applications where power needs to be distributed throughout an application to multiple locations, and hence multiple mechanical linkages would normally be required. The supercapacitor version is most suited to applications with high peak to average load ratios and noisy load cycles, and the battery version could be seen as a low cost route to range extend a battery electric vehicle.
Terdich N, Martinez-Botas R, 2013, Experimental efficiency characterization of an electrically assisted turbocharger, ISSN: 0148-7191
Electrically assisted turbochargers consist of standard turbochargers modified to accommodate an electric motor/generator within the bearing housing. Those devices improve engine transient response and low end torque by increasing the power delivered to the compressor. This allows a larger degree of engine down-sizing and down-speeding as well as a more efficient turbocharger to engine match, which translates in lower fuel consumption. In addition, the electric machine can be operated in generating mode during steady state engine running conditions to extract a larger fraction of the exhaust energy. Electric turbocharger assistance is therefore a key technology for the reduction of fuel consumption and CO2 emissions. In this paper an electrically assisted turbocharger, designed to be applied to non-road medium duty diesel engines, is tested to obtain the turbine and electrical machine efficiency characteristics. The radial turbine is of the variable geometry type where the mass flow characteristics are changed by varying the vanes angle. The motor/generator is of the switched reluctance type and has a maximum speed of over 135,000 rev/min. The turbine and the motor/generator have been characterized with two different experiments. The turbine has been tested in cold flow on a specifically built dynamometer available at Imperial College. This allowed extending the turbine maps available from the manufacturer and to separate the bearing and heat transfer losses from the aerodynamic performance. To test the electrical machine, a prototype of the assisted turbocharger has been modified by removing the compressor and by placing the bearing housing on gimbal bearings. By measuring the speed, the reaction torque on the bearing housing and the electrical power, the efficiency of the electrical machine has been calculated. Turbine testing results show a peak turbine efficiency of 69% at a velocity ratio of 0.65 with 60% vane opening. Results in the electrical machine testing
Romagnoli A, Copeland CD, Martinez-Botas R, et al., 2013, Comparison Between the Steady Performance of Double-Entry and Twin-Entry Turbocharger Turbines, JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME, Vol: 135, ISSN: 0889-504X
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- Citations: 28
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