Harry C. Watson

Fuel-cycle greenhouse gas emissions from alternative fuels in Australian heavy vehicles

This paper quantifies the expected pre-combustion and combustion emissions of greenhouse gases from Australian heavy vehicles using alternative fuels. We use the term exbodied emissions for these full fuel-cycle emissions. The fuels examined are low sulfur diesel (LSD), ultra-low sulfur diesel (ULS), compressed natural gas (CNG), liquefied natural gas (LNG), liquefied petroleum gas (LPG), ethanol (from lignocellulose), biodiesel and waste oil. Biodiesel and ethanol have the lowest exbodied greenhouse gas emissions (in grams greenhouse gases per kilometre travelled). Biodiesel reduces exbodied greenhouse gas emissions from 41% to 51% whereas ethanol reduces emissions by 49–55%. In fact, both emit larger quantities of CO2 than conventional fuels, but as most of the CO2 is from renewable carbon stocks that fraction is not counted towards the greenhouse gas emissions from the fuel. The gaseous fuels (LPG, CNG) come next with emissions that range from 88% to 92% of diesel. The emissions of greenhouse gases from diesel are reduced if waste oil is used as a diesel extender, but the processing energy required to generate LSD and ULS in Australia increase their greenhouse gas emissions compared to diesel fuel. The extra energy required liquefy and cool LNG means that it has the highest exbodied greenhouse gas emissions of the fuels that were considered.

Model Predictive Control of a Fuel Injection System with a Radial Basis Function Network Observer

This paper proposes a new Model Predictive Control scheme incorporating a Radial Basis Function Network Observer for the fuel injection problem. Two new contributions are presented here. First a Radial Basis Function Network is used as an observer for the air system. This allows for gradual adaptation of the observer, ensuring the control scheme is capable of maintaining good performance under changing engine conditions brought about by engine wear, variations between individual engines, and other similar factors. The other major contribution is the use of model predictive control algorithms to compensate for the fuel pooling effect on the intake manifold walls. Two model predictive control algorithms are presented which enforce input, and input and state constraints. In this way stability under the constraints is guaranteed. A comparison between the two constrained MPC algorithms is qualitatively presented, and conclusions are drawn about the necessity of constraints for the fuel injection problem. Simulation results are presented that demonstrate the effectiveness of the control scheme, and the proposed control approach is validated on a four-cylinder spark ignition engine.

Gaussian networks for fuel injection control

Abstract This paper proposes a radial basis function (RBF) based approach for the fuel injection control problem. In the past, neural controllers for this problem have centred on using a cerebellar model articulation controller (CMAC) type network with some success. The current production engine control units also use look-up tables in their fuel injection controllers, and if adaptation is permitted to these look-up tables the overall effect closely mimics the CMAC network. Here it is shown that an RBF network with significantly fewer nodes than a CMAC network is capable of delivering superior control performance on a mean value engine model simulation. The proposed approach requires no a priori knowledge of the engine systems, and on-line learning is achieved using gradient descent updates. The RBF network is then implemented on a four-cylinder engine and, after a minor modification, outperforms a production engine control unit.

An Online Power-Balancing Strategy for a Parallel Hybrid Electric Vehicle Assisted by an Integrated Starter Generator

Power-flow-control techniques that are capable of handling inefficiencies of both the electric motor/generator (EMG) and the internal combustion engine (ICE) are required to fully explore the fuel-saving potential of fully hybridized parallel hybrid electric vehicles (PHEVs). We propose an online power-flow-control strategy for fully hybridized PHEVs based on the power-balancing strategy (PBS), which controls the ICE within its peak-efficiency region by using the electrical system. We introduce a new PHEV assisted by an integrated starter generator (ISG) or ISG-assisted PHEV, in which the ISG supports the downsized EMG to maintain the electrical systems efficiency close to its peak efficiency and, therefore, to enhance the fuel-saving capability of the PBS controller. The key contributions of this study are given as follows: 1) identification of the ICEs peak-efficiency region as a function of the discharging and recharging efficiencies of the electrical system; 2) a new more fuel-efficient HEV architecture; and 3) proper regulation of the state of charge while maintaining infrequent stopping and restarting of the ICE by direct control of the ICEs energy output. Results show that the PBS controller achieves fuel efficiencies similar to the offline benchmark controller using the equivalent consumption minimization strategy. The PBS controller saves up to 9.3% of fuel on the ISG-assisted PHEV, compared with an equally powered PHEV without the ISG.

Particle Swarm Optimisation for Protein Motif Discovery

In this paper, a modified particle swarm optimisation algorithm is proposed for protein sequence motif discovery. Protein sequences are represented as a chain of symbols and a protein sequence motif is a short sequence that exists in most of the protein sequence families. Protein sequence symbols are converted into numbers using a one to one amino acid translation table. The simulation uses EGF protein and C2H2 Zinc Finger protein families obtained from the PROSITE database. Simulation results show that the modified particle swarm optimisation algorithm is effective in obtaining global optimum sequence patterns, achieving 96.9 and 99.5 classification accuracy respectively in EGF and C2H2 Zinc Finger protein families. A better true positive hit result is achieved when compared to the motifs published in PROSITE database.

Development of a Direct Injection High Efficiency Liquid Phase LPG Spark Ignition Engine

Direct Injection (DI) is believed to be one of the key strategies for maximizing the thermal efficiency of Spark Ignition (SI) engines and meet the ever-tightening emissions regulations. This paper explores the use of Liquefied Petroleum Gas (LPG) liquid phase fuel in a 1.5 liter SI four cylinder gasoline engine with double over head camshafts, four valves per cylinder, and centrally located DI injector. The DI injector is a high pressure, fast actuating injector enabling precise multiple injections of the finely atomized fuel sprays. With DI technology, the injection timing can be set to avoid fuel bypassing the engine during valve overlap into the exhaust system prior to combustion. The fuel vaporization associated with DI reduces combustion chamber and charge temperatures, thereby reducing the tendency for knocking. Fuel atomization quality supports an efficient combustion process. Furthermore, the spray-guided combustion process has significant thermodynamic benefits over wall or air guided combustion resulting is near optimal combustion. Injection timings and compression ratio are optimized for best performances over Wide Open Throttle (WOT) conditions running homogeneous at stoichiometry or spray-guided stratified lean of stoichiometry. The paper also explores advantages of Jet Ignition (JI) versus standard SI in the lean spray-guided stratified mode of operation. Effects of fuel properties on gas exchange, mixture formation, in-cylinder charge cooling, wall-spray interactions, turbulent combustion evolution and knock occurrence are taken into account. Results are presented in terms of brake mean effective pressure, specific fuel consumption, efficiency and specific CO 2 production showing significant improvements of LPG over gasoline for the reduced green house gas formation potential. This paper is a contribution to the development of a high efficiency gaseous fuel SI engine for the Australian market.

Application of membrane gas separation to oxygen enrichment of diesel engines

Abstract This work has demonstrated that the use of oxygen enriched air in the inlet to a direct injection diesel engine can result in a significant reduction in particulates emissions (in excess of 80% at full load), increased thermal efficiency if injection timing control is employed, substantial reductions in exhaust smoke under most conditions, ability to burn inferior quality fuels which is economically and environmentally attractive and achievement of turbo-charged levels of output. NO x emissions are generally increased due to the improved combustion efficiency, but can be reduced to normally aspirated engine levels at some efficiency penalty. The successful use of a self-contained oxygen generation system using a prototype flat sheet polymeric membrane module, compressor and turbocharger design based on the initial engine test work with oxygen from compressed gas cylinders has been demonstrated for the first time. This work has identified an important role for membrane gas separation in this area and represents a major step forward in improving diesel engine efficiency and emission control. Current work is aimed at optimising membrane/turbine/compressor combinations with emphasis on the use of improved hollow fibre membranes and demonstration on an operating diesel engine.

Comparing the Performance and Limitations of a Downsized Formula SAE Engine in Normally Aspirated, Supercharged and Turbocharged Modes

This paper compares the performance of a small two cylinder, 430 cm engine which has been tested in a variety of normally aspirated (NA) and forced induction modes on 98-RON pump gasoline. These modes are defined by variations in the induction system and associated compression ratio (CR) alterations needed to avoid knock and maximize volumetric efficiency (ηVOL). These modes included: (A) NA with carburetion (B) NA with port fuel injection (PFI) (C) Mildly Supercharged (SC) with PFI (D) Highly Turbocharged (TC) with PFI The results have significant relevance in defining the limitations for small downsized spark ignition (SI) engines, with power increases needed via intake boosting to compensate for the reduced swept volume. Performance is compared in the varying modes with comparisons of brake mean effective pressure (BMEP), brake power, ηVOL, brake specific fuel consumption (BSFC) and brake thermal efficiency (ηTH). The test engine used in experiments was specifically designed and configured for Formula SAE, SAE’s student Formula race-car competition. A downsized twin cylinder in-line arrangement was chosen, which featured double overhead camshafts and four valves per cylinder. Most of the engine components were specially cast or machined from billets. Experimental results showed BSFC or ηTH values in the order of 240 g/kWh or 34% could be achieved. TC BMEP values in the region of 25 bar were also achieved, the highest recorded for small engines on pump gasoline [1]. The engine was installed into successive Melbourne University Racing (MUR) vehicles in 2003 and 2004, where it was very competitive, finishing first in the fuel economy event at the 2004 Australasian competition. INTRODUCTION In recent times, research into SI engine downsizing has grown in popularity [2,3,4] as governments begin to limit carbon dioxide (CO2) emissions and consumers strive for cost savings due to rising oil prices. Thus, manufacturers are trying to improve performance and efficiency while meeting legislative pollutant emissions standards. Downsizing, defined as a reduction in the engine swept volume with performance retained by intake boosting, appears to be a major way forward in satisfying consumer and manufacturer requirements. However, for downsized engines to be comparable to their larger counterparts, the specific output performance must be increased by a ratio equal to the reduction in engine size [3]. This high specific output can only be achieved with the help of increased engine speeds and/or intake boosting. This increases the induced amount of air and fuel, thus enabling the performance of the downsized engine to be improved to match its larger counterpart. Turbocharging seems to be the most acceptable solution to meeting the requirements, with high pressure ratios achievable and well documented improvements in efficiency [4,5,6,7,8]. TC downsized engines also offer other benefits besides obvious efficiency gains. Engine packaging and overall powerplant weight reduction is improved, which further enhances vehicle efficiency and dynamic performance. Smaller engines also offer mass reductions in engine out exhaust emissions, with reduced need for stratified lean burn strategies to improve efficiency. Thus legislative specific emission standards can be met using conventional after treatment methods (three-way catalyst) at stoichiometric operating conditions. However, disadvantages also exist with smaller downsized engines. The increased specific output places greater strain on the internal components of the engine due to the increased combustion and inertia loading associated with intake boosting and increased engine speeds. This increases the cost and complexity as there is a need to redesign internal components using improved materials and manufacturing processes. More elaborate control systems are also needed to prevent component failure. These measures are required to ensure reliability and durability over the engine’s life cycle, resulting in increased costs. The higher pressures and temperatures associated with TC engines also increase the occurrence of uncontrolled combustion, mainly knock in the end-gas region, which further deteriorates engine performance and reliability [6,9]. BRAND UniMelb ‘WATTARD’ TYPE Parallel twin 4 stroke SI, Liquid-cooled, Integral clutch/ transmission CAPACITY 433.8 cm BORE x STROKE 69 x 58 mm FIRING ORDER Unequal (0°, 180° CA) COMPRESSION RATIO 9-13:1 with piston modification COMBUSTION CHAMBER Pent roof, Central spark plug VALVE ACTUATION 8-valve DOHC VALVE TIMING IVO 24° BTDC IVC 72° ABDC EVO 57° BBDC EVC 9° ATDC LUBRICATION Dry sump ENGINE MANAGEMENT Motec M4 EMS CLUTCH Multi wet plate TRANSMISSION Constant mesh (3 forward gears) The original intent of this development program was to achieve success in Formula competition by using a far superior engine package when compared to conventional OEM based motorcycle units. However, from the research and development process, results from this small engine operating in a variety of modes has significance in defining the limitations for small downsized gasoline engines. For instance, is the performance limited by engine mechanics, deliverable manifold absolute pressure (MAP) levels, normal or abnormal combustion or a combination of these factors? Results may give some insight to the extent by which engines can be downsized and the specific areas where future research should be directed. This has significant relevance to manufacturers, who continue to strive for swept capacity reductions, while maintaining performance with improved efficiency.

A novel approach to disturbance rejection in idle speed control towards reduced idle fuel consumption

Abstract Idle speed control remains one of the most challenging problems in the automotive control field owing to its multiple-input, multiple-output structure and the step nature of the disturbances applied. In this paper a simulation model is described for a 4.0 l production engine at idle which includes the standard bypass air valve and spark advance dynamics, as well as the e ects of operating point on cycle-by-cycle combustion-generated torque variations. A model predictive control scheme is then developed for the idle bypass valve and spark advance. The idle speed control algorithm is based on rejecting the torque disturbance using model predictive control for the bypass valve duty cycle while minimizing the transient e ects of the disturbance by adjusting the spark advance. Simulation results are presented to demonstrate the effects of different elements of the controller such as levels of spark offset from minimum spark advance for best torque at idle and feedforward load previews. Compensation of the effects of cyclic variation in combustion torque is also implemented in the controller and its benefits are discussed.

Hydrogen assisted jet ignition for near elimination of NOx and cyclic variability in the S.I. Engine

The performance of a combustion initiation system for the Otto cycle engine is described which uses a pre-chamber of 1.5% main chamber clearance volume, fuelled with minute quantities of hydrogen. The order of magnitude faster flame kernel growth, obtained with hydrogen mixtures compared with hydrocarbon fuels, provides enhanced jet momentum from a small proportion of the total charge energy, and active radicals and intermediate species which assist in initiating combustion in mixtures significantly leaner than the lean flammability limit with normal ignition. The performance results demonstrate the ASTM CFR engine working at up to 70% maximum torque with NO x emissions close to ambient levels. The hydrogen assisted jet ignition, HAJI, use to achieve this also confers extremely stable combustion with coefficients of variation of peak cylinder pressure and specific work per engine cycle reduced by 50 to 80% from those normally achieved with this engine. This allows increased thermal efficiency at ultra lean operation, at relative air/fuel ratios of around 2, and about two numbers increase in the highest useful compression ratio. There is no lean limit of combustion within the range of usable engine torque. Operation with relative air/fuel ratios of 5 have been achieved. With methanol as the main chamber fuel, the results presented here demonstrate an improvement in maximum indicated thermal efficiency of 15 per cent simultaneously with the low NO x emissions. The hydrocarbon emissions remain high which is a characteristics of this research engine.