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Watson, Harry C.
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An Integrated Model of Energy Transport in a Reciprocating, Lean Burn, Spark Ignition Engine

SAE International Journal of Engines

University of Melbourne-Peter A. Dennis, Michael J. Brear, Harry C. Watson, Pedro J. Orbaiz, Payman Abbasi Atibeh
  • Journal Article
  • 2015-01-1659
Published 2015-04-14 by SAE International in United States
This paper presents a combined experimental and numerical method for analysing energy flows within a spark ignition engine. Engine dynamometer data is combined with physical models of in-cylinder convection and the engine's thermal impedances, allowing closure of the First Law of Thermodynamics over the entire engine system. In contrast to almost all previous works, the coolant and metal temperatures are not assumed constant, but rather are outputs from this approach. This method is therefore expected to be most useful for lean burn engines, whose temperatures should depart most from normal experience.As an example of this method, the effects of normalised air-fuel ratio (λ), compression ratio and combustion chamber geometry are examined using a hydrogen-fueled engine operating from λ = 1.5 to λ = 6. This shows large variations in the in-cylinder wall temperatures and heat transfer with respect to λ. In keeping with our other works, thermal efficiency also appears to be limited by in-cylinder heat transfer on the rich side of optimum λ, and diminishing combustion quality on the lean side.By comparing different compression…
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Lean Burn Performance of a Natural Gas Fuelled, Port Injected, Spark Ignition Engine

University of Melbourne-Payman Abbasi Atibeh, Peter A. Dennis, Pedro J. Orbaiz, Michael J. Brear, Harry C. Watson
Published 2012-04-16 by SAE International in United States
This paper presents a study of the performance of a lean burn, natural gas-fuelled, naturally aspirated, spark ignition engine for an E class vehicle. Engine performance and exhaust emissions (NO, CO, and UHC) data are first discussed. An energy balance of the engine operating at different loads and air-fuel ratios is then presented, and used to explain why engine efficiency varies with air-fuel ratio. Finally, the hot start drive cycle CO2e (CO2 equivalent) emissions are estimated for a vehicle with this engine. This shows a potential for significant reduction in vehicle greenhouse gas emissions compared to an equivalent gasoline-fuelled vehicle.
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Performance of a Port Fuel Injected, Spark Ignition Engine Optimised for Hydrogen Fuel

Ford Motor Company of Australia-Glen Voice
University of Melbourne-Peter A. Dennis, Robert J. Dingli, Payman Abbasi Atibeh, Harry C. Watson, Michael J. Brear
Published 2012-04-16 by SAE International in United States
This paper presents a study of the performance of a 6-cylinder, spark-ignited, port-fuel-injected, production engine modified for hydrogen fueling. The engine modifications include turbo-charging, multiple fuel injectors per port and charge-dilution control techniques. Pumping losses are reduced through ultra-lean burn and throttle-less operation alongside high charge dilution ratio control achieved by twin independent variable cam timing without external EGR.Lean-burn combustion, engine-out emissions and brake thermal efficiency results are examined in detail. In particular, low NO emissions and brake thermal efficiencies near 38% are observed experimentally at the same operating conditions. The former is explained in terms of the usual thermal NOx pathway. Usage of throttle position, injection timings and cam timings for avoiding preignition and knock over the entire engine map are also discussed. Finally, first law analyses of energy losses for varying cam timings, varying manifold pressure and varying torque are presented and used to suggest reasons for values of λ for optimal BTE in each case.
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Performance Comparison of Engine Down-Sized to High Efficieincy ICEs in Optimized Hybrid Vehicles

University of Melbourne-Harry C. Watson, Sunil Alihikari
Published 2012-04-16 by SAE International in United States
A real time energy management (EMS) optimizing algorithm is introduced that performs similar to offline dynamic programming (DP) for parallel HEVs. The EMS and the DP are compared, especially with the addition of a local hill climbing technique, to the example performance prediction of the fuel consumption of a 1.67 tonne large car using a 50 kW Honda Insight engine (representing 65% power reduction from standard) as reference. Then the performance of the vehicle in HEV mode, with a parallel 30 kW motor/generator is examined. The average improvement of this vehicle over five drive cycles from around the world is about 50% reduction in fuel consumption. Next the engine is replaced with an advanced SI turbocharged engine with assisted ignition which returns the performance to that expected of this class of car i.e. 0-100 km/h acceleration time of 7 s. This results in a 14% average reduction in fuel consumption across the five cycles compared with the base Honda engine. Then in optimized hybrid configuration, the advanced engine powertrain demonstrates that not only is a…
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Combustion System Development and Analysis of a Downsized Highly Turbocharged PFI Small Engine

SAE International Journal of Engines

University of Melbourne, Australia-William P. Attard, Elisa Toulson, Ferenc Hamori, Harry C. Watson
  • Journal Article
  • 2010-32-0093
Published 2010-09-28 by SAE International in United States
This paper provides some insight into the future direction for developing smaller capacity downsized engines, which will be needed to meet tight CO₂ targets and the world's future powertrain requirements. This paper focuses on the combustion system development and combustion analysis results for a downsized 0.43-liter highly turbocharged engine. The inline two-cylinder engine used in experiments was specifically designed and constructed to enable 25 bar BMEP. Producing this specific output is one way forward for future passenger vehicle powertrains, enabling in excess of 50% swept capacity reduction whilst maintaining comparable vehicle performance.Previous experiments and analysis have found that the extent to which larger engines can be downsized while still maintaining equal performance is combustion limited. Hence, small engine combustion is explored over a number of parametric studies, including a range of manifold absolute pressures up to 270 kPa, engine speeds exceeding 10,000 rev/min and compression ratios ranging from 9 to 13. Experimental results indicate that small engine combustion hurdles can be overcome to reliably extend the specific output to 25 bar BMEP. This is believed…
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Combustion System Development and Analysis of a Carbureted and PFI Normally Aspirated Small Engine

University of Melbourne, Australia-William P. Attard, Elisa Toulson, Ferenc Hamori, Harry C. Watson
Published 2010-09-28 by SAE International in United States
This paper focuses on the combustion system development and combustion analysis results for a normally aspirated 0.43-liter small engine. The inline two-cylinder engine used in experiments has been tested in a variety of normally aspirated modes, using 98-RON pump gasoline. Test modes were defined by alterations to the induction system, which included carburetion and port fuel injection fuel delivery systems. The results from this paper provide some insight into the combustion effects for small cylinder normally aspirated spark ignition engines. This information provides future direction for the development of smaller engines as oil prices fluctuate and CO₂ emissions begin to be regulated.Small engine combustion is explored with a number of parametric studies, including a range of manifold absolute pressures up to wide open throttle, engine speeds exceeding 10,000 rev/min and compression ratios ranging from 9 to 13. Combustion system optimization through compression ratio development enabled the engine to achieve 37% brake thermal efficiency and 13 bar brake mean effective pressure. Hence, the test engine performance and efficiency results demonstrate that smaller bore engines can match…
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4 L Light Duty LPG Engine Evaluated for Heavy Duty Application

SAE International Journal of Fuels and Lubricants

Univ. of Melbourne-Mohammad Ali Khan, Harry C. Watson
  • Journal Article
  • 2010-01-1463
Published 2010-05-05 by SAE International in United States
Many applications of liquefied petroleum gas (LPG) to commercial vehicles have used their corresponding diesel engine counterparts for their basic architecture. Here a review is made of the application to commercial vehicle operation of a robust 4 L, light-duty, 6-cylinder in-line engine produced by Ford Australia on a unique long-term production line. Since 2000 it has had a dedicated LPG pick-up truck and cab-chassis variant.A sequence of research programs has focused on optimizing this engine for low carbon dioxide (CO₂) emissions. Best results (from steady state engine maps) suggest reductions in CO₂ emissions of over 30% are possible in New European Drive Cycle (NEDC) light-duty tests compared with the base gasoline engine counterpart. This has been achieved through increasing compression ratio to 12, running lean burn (to λ = 1.6) and careful study (through CFD and bench tests) of the injected LPG-air mixing system.The outcome of this work (and others) has stimulated a major Australian Government investment in gaseous fuels consistent with increased home consumption of LPG as over half of local LPG production is…
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Exploring the Geometric Effects of Turbulence on Cyclic Variability

Orbital Co. Ltd.-Pouria Mehrani
Univ. of Melbourne-Harry C. Watson
Published 2010-04-12 by SAE International in United States
Cyclic variability in spark ignition engine combustion, especially at high dilution through lean burn or high EGR rates, places limits on in-cylinder NOx reduction and thermal efficiency. Flame wrinkling, resulting from interactions with turbulence, is a potential source of cyclic variations in turbulence. Previous studies have shown that flame kernels are subject to significant distortions when they are smaller than the integral length scale of turbulence. With the assumption that flame development is not subject to noticeable variations, after it reaches the integral length scale, the authors have shown that turbulent-burning-caused combustion variability can be successfully modeled as a function of laminar flame speed and turbulence intensity. This paper explores the contributions of flame wrinkling to flame kernel growth variation. As the kernel growth problem is complex, this study only explores one of the many aspects of the problem. The complete description of the phenomenon requires consideration of additional effects, which are discussed here. However it is shown that geometric variations of the flame kernel can potentially constitute a significant portion of variability. These variations…
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The Performance and Emissions of the Turbocharged Always Lean Burn Spark Ignition (TC-ALSI) Engine

Orbital Co Ltd.-Pouria Mehrani
Univ. of Melbourne-Harry C. Watson
Published 2010-04-12 by SAE International in United States
This paper extends previous development of the ALSI concept, by investigating the performance delivered with a turbocharged version of this engine. The research is based on extensive experimental research with lean burn, high compression ratio engines using hydrogen, LPG, CNG and gasoline fuels. It also builds on recent experience with highly boosted spark ignition gasoline and LPG engines and single cylinder engine research used extensively for model calibration. The final experimental foundation is the wide ranging evaluation of jet assisted ignition that generally allows a lean limit mixture shift of more than one unit of lambda with consequential benefits of improved thermal efficiency and close to zero NOx. The paper describes the capability of the ultra lean burn spark ignition engine with the mild boost needed provided by a Honeywell turbocharger. The concept is operation in the air-fuel ratio domain of the diesel engine but with essentially homogenous charge, although some stratification may be desirable. To achieve exceptional thermal efficiency this engine has optimised compression ratio but variable valve timing that enables reduction in the…
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The Lean Burn Direct-Injection Jet-Ignition Flexi Gas Fuel LPG/CNG Engine

University of Ballarat-Alberto A. Boretti, Harry C. Watson
Published 2009-11-02 by SAE International in United States
This paper explores through engine simulations the use of LPG and CNG gas fuels in a 1.5 liter Spark Ignition (SI) four cylinder gasoline engine with double over head camshafts, four valves per cylinder equipped with a novel mixture preparation and ignition system comprising centrally located Direct Injection (DI) injector and Jet Ignition (JI) nozzles. With DI technology, the fuel may be introduced within the cylinder after completion of the valve events. DI of fuel reduces the embedded air displacement effects of gaseous fuels and lowers the charge temperature. DI also allows lean stratified bulk combustion with enhanced rate of combustion and reduced heat transfer to the cylinder walls creating a bulk lean stratified mixture. Bulk combustion is started by a Jet Ignition (JI) system introducing in the main chamber multiple jets of reacting gases for enhanced rate of combustion, initiating main chamber burning in multiple regions with reduced sensitivity to mixture state and composition. Coupling of JI and DI allows the development of a lean burn engine making possible operation up to main chamber…
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