Combustion Features' Theory And Experiment Study For Micro-engine Of Homogeneous Charge Compression Ignition (HCCI)

With the development of micro-nanometer and micro-manufacturing technology, Power Micro-device appears. Power Micro-device has much smaller volume and higher energy density than traditional battery, so it will be wide applied in industrial production. Based on the analysis of micro-engine and Homogeneous Charge Compression Ignition (HCCI) research at home and abroad, this paper makes an experimental research on the combustion characteristic of HCCI in micro-engine—the key part of Power Micro-device, which provides basic research for the design of micro-engine.HCCI technology is considered as the new generation of combustion to satisfy the strict emission regulations in the future for its low emission of NOx and Particular Matter (PM) and high heat efficiency. So the HCCI technology is attracted more and more attention from academy and industry of international internal-combustion engine science. As a kind of high energy and portability device, Power Micro-device is usually close to user. So the combustion characteristic (such as emission) of Power Micro-device should be strictly required for the health of user. HCCI technology is one of the best choices for Micro-device to satisfy this requirement.This paper is divided into six chapters. In the first chapter, the research state of micro-engine and HCCI at home and abroad is firstly summarized, then the source and significance of research is introduced, and finally the main context of this paper is presented.In the second chapter, the basic theory of micro-engine HCCI combustion is researched from the characteristic of micro-engine combustion, process and characteristic of HCCI combustion, process control of HCCI combustion, model and application classification of HCCI combustion. Meanwhile, traditional combustion and HCCI combustion is compared, the existed problems of HCCI combustion are pointed and finally the develop trend of HCCI combustion is explored.In the third chapter, the experiment system and equipments of HCCI combustion are introduced. In the fourth chapter, the combustion characteristic of experiment engine is analyzed by Indicated Mean Effective Pressure (IMEP), indicated efficiency, heat release rate, combustion duration and relation between emission and engine speed. The change process of HCCI combustion structure in different speed is analyzed by optics picture and finally the radical form and evolution process of HCCI combustion in different speed is analyzed. In the fifth chapter, the key design parameters (squish distance, cylinder wall temperature and combustion chamber geometry) that effect micro-engine HCCI combustion are analyzed. In the sixth chapter, the conclusion of this paper is obtained.The experimental research of this paper is carried on the reconstructed and single-cylinder HCCI engine from the two-stroke water-cooled and single-cylinder mini-engine (O.S.25), and the fuel is diethyl ether. The research results of this paper indicate:①During the HCCI combustion process, the unburned or partial burned hydrocarbon is high, namely the emission value of HC and CO is high, but the harmful and polluted emission NOx is very low.②The design of squish distance 0.25mm for Vibrating Micro-engines for Power Generation and Microsystems Actuation (VIMPA)is feasible. Meanwhile, the optimal squish distance is 0.75mm.③In order to acquire good scavenging efficiency and relatively high combustion efficiency, the better design in micro-engine of VIMPA is to adopt cool crankcase and warm/hot cylinder wall.④Bowel combustion chamber is more sensitive than pancake combustion chamber in quenching, so the pancake combustion chamber is optimal choice for the centimeter scale HCCI engine (such as VIMPA).The research of this paper provides some theory for combustion characteristic of micro-scale HCCI and the basic work for further develop and design micro HCCI engine.