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ABSTRACT
Homogenous charge compression ignition (HCCI) combines the advantages of spark ignition (SI) and compression ignition (CI) engines to improve fuel consumption and emission levels. HCCI engines have the advantage of relatively higher engine efficiency than SI engines while maintaining lower emissions levels than CI engines. Combustion in HCCI engines occurs spontaneously at any location once the fuel-air mixture reaches its chemical activation energy. Pistons have a major effect on controlling the combustion inside the combustion chamber of an HCCI engine. Many researchers have studied various designs for pistons to improve HCCI engines. The aim of this study is to explore these different types of pistons and their designs in terms of improving the performance of HCCI engines fuelled with gasoline. The most common pistons used in HCCI are two-stroke pistons, bowl types, specialised pistons, and dome-shaped pistons; each offers distinct advantages and disadvantages. Software simulation is the latest way of determining the best piston to be used for HCCI engines, as it is more cost effective and less time consuming than experiments. Overall, bowl type pistons offer reduced fuel consumption and a higher load capacity when used in an HCCI engine.
Keywords: HCCI Engine; gasoline; performance; piston.
INTRODUCTION
Homogenous Charge Compression Ignition (HCCI) gasoline-based engines are promising innovations in internal combustion engine research. The use of HCCI technology improves engines' performance such as higher combustion efficiency and lower emission levels of NOx and particulate matter [1-3]. These innovations come at the same time as increasing global concern for greenhouse gases leads to demands of automotive industries to manufacture engines with green technology. The drive for improving the efficiency of gasoline-fuelled HCCI engines prompted the automotive industry to create designs that offer optimum engine efficiency. However, various challenges limit the successful operation of HCCI engines. These include controlling the combustion phasing, extending the operating range, and the issue of high unburned hydrocarbon and carbon monoxide emissions [4-7]. Gasoline-based HCCI engines are temporary solutions to the problems of conventional and traditional gasoline engines. They are a high-efficiency technology in terms of engine performance and offer environment-friendly automotive solutions [8]. The challenges of HCCI include vibration, noise, knocking, and limited power output. Vibration and noise are results of the fast burning speeds in combustion HCCI engines...