Homogeneous Charge Compression Ignition (HCCI) is a promising method for combustion engines to provide a substantial reduction in fuel consumption and formation of both nitrogen oxides and soot pollutants in automotive and stationary engines. Control of HCCI combustion timing is essential for the successful integration of the HCCI concept in real applications. This thesis concentrates on control oriented modeling and experimental study of HCCI combustion for control of ignition timing in HCCI engines. A detailed experimental study of HCCI with over 600 operating points on two different engines is done to characterize the complex relationship among the engine variables, the ignition timing and the exhaust temperature. This leads to identifying regions with distinct patterns of cyclic variation for HCCI ignition timing. In addition, main influential factors on the variations of ignition timing and exhaust temperature in HCCI engines are determined. A dynamic full-cycle physics based Control Oriented Model(COM) is derived from using the experimental data and simulations from an HCCI thermo-kinetic model. The COM is validated with a large number of transient and steady-state experimental points. The validation results show that the COM captures the key HCCI dynamics with a high degree of accuracy for control applications. The COM is computationally efficient and all inputs of the model can be readily measured or estimated on a real engine. This makes the COM simple and fast enough for use as an off-line simulation bed to design and evaluate different strategies for physics-based control of combustion timing in HCCI engines.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 89-93).

Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2002. / Includes bibliographical references (leaves 138-144). Also available in electronic version. Access restricted to campus users.

Promotionsarbeit--Eidgenössische Technische Hochschule, Zürich. / Lebenslauf.

Thesis (Ph. D.)--Columbia University. / Academic record.

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One method of using alternativefuels in diesel engines is by adopting amixed combustion process called dualfu elling w h er e alt ernativ e fu eI s uc h as natural gas (Ir{ G) is induc e d into the cylinder as a primary fuel with air and is subsequently isnited with a pilot injection of dieselfuel. The ignition delay in a dualfuel (DF) engine is differentfrom that in a diesel engine because the primaryfuelalters the properties of the charge, r e duc e o xy g e n av ailable and under go e s pr e -ignitio n r e ac tio n s durin g c o mp r e s s io n. V ario u s c o nclu sio n s of DF ignition delay have beenreachedusing different engines. In the presentwork a constantvolume combustionvessel (CVCV) has beenusedto study the ignition delay of aDF combustionpFocess. E xp erim e nt s hav e b e e n p e rform e d to inv e s tigat e th e i gniti o n d e lay p e rio d at dffi r e nt initial t e mp e r atur e s andpressures. The results obtainedwere usedto modify the Hu and Milton'ss DF ignition delay correlation. The proposed coruelation predicts a delay periodfor a wide range of initialtemperatures andpressures. The trends exhibitedby the correlation are consistentwith DF ignition delay engine tests datafrom other researchersl'2. In particular, it explains why some reported tests results show that ignition delay is always rising while others show that it decreases temporarily before rising againto very highvalues. The rising of ignition delay occurs withlow pilot diesel quantities and the latter with high one s.

An investigation on the sequential turbocharging of a Kelvin TFSC6 6-cylinder 4- stroke marine diesel engine developing 320 kW at 1200 r/min is reported in this thesis. The sequential turbocharging (ST) system, utilising turbochargers of unequal size, resulted in significant improvement when compared with previously designed systems. The engine test results show that the new sequential turbocharging system improves the engine performance at both high speeds and low speeds except at or near to the 'transfer' speed. The engine low speed performance is obviously improved with the fuel saving of up to 7 g/kwh for the 1st sequence. The engine high speed performance is also improved for the 2nd sequence where both turbochargers are in operation. There is some boost air leakage from the delivery pipe which is used for connecting the peak unit to the intercooler inlet. This restricts the 2nd sequence gains. An optimised sequence transfer control mode is also proposed in this research and validated by both test and simulation results. Two control valves, one at the peak unit turbine inlet and the other at the compressor outlet, are specifically designed for the ST system and both of them worked very well during the engine test programme. Both simulation models - "Filling& Emptying" and "Method of Characteristic" were modified and used for the sequential turbocharging simulation. The modified program of the "Filling& Emptying" model can be used to analyse and compare the effects of different exhaust systems. It can also be applied to simulate and design a pulse converter system for a sequential turbocharged diesel engine. The modification on the "MOC" program makes it possible to simulate the exhaust pressure wave for the ST system with different turbocharger arrangements (concentrated or separated). The consideration of pressure losses in the 'three branch junction' boundary improves the simulation accuracy. In addition, a comprehensive engine test data acquisition and control system has been developed in this study. The advanced system with many new features can be used for engine condition monitoring. diagnosis and other similar applications for engine development and test. The efficiency and reliability of the system have been corroborated by the engine test process. The real time data process, analysis and display in various forms are available using the developed program with 'LabVIEW'. The proposed self-adaptive auto-load setting with optimised parameters is validated as an economic solution for engine load control with an early type of hydraulic dynamometer.

No description available.