Jacky Guezet

Progress in Diesel HCCI Combustion Within the European SPACE LIGHT Project

The purpose of the European « SPACE LIGHT» (Whole SPACE combustion for LIGHT duty diesel vehicles) 3-year project launched in 2001 is to research and develop an innovative Homogeneous internal mixture Charged Compression Ignition (HCCI) for passenger cars diesel engine where the combustion process can take place simultaneously in the whole SPACE of the combustion chamber while providing almost no NOx and particulates emissions. This paper presents the whole project with the main R&D tasks necessary to comply with the industrial and technical objectives of the project. The research approach adopted is briefly described. It is then followed by a detailed description of the most recent progress achieved during the tasks recently undertaken. The methodology adopted starts from the research study of the in-cylinder combustion specifications necessary to achieve HCCI combustion from experimental single cylinder engines testing in premixed charged conditions. With such information collected, 1D CFD calculations are then used to evaluate the potential of different ways and concepts to provide the in-cylinder global conditions favourable to this combustion mode. Associated 3D CFD calculations complete these results by providing information about the potential of these concepts to achieve the specified local conditions inside the combustion chamber. Supported by all these calculations, by some optical diagnostics in transparent engines, by visualisation and detailed characterisation of the sprays of the new injection system developed, the design process of the most promising HCCI engine concept selected has been undertaken. It is based on a unique combination of flexible variable valve actuation technology, advanced injection system with SPACE spray pattern, air and EGR charging and mixing strategies,... The corresponding hardware has been manufactured and integrated in prototype single-cylinder engines. The most recent engine tests results achieved with the SPACE LIGHT diesel HCCI concept are presented and discussed. They already show impressive reduction of NOx and particulates as expected compared to conventional diesel combustion. The most interesting aspect is that the high efficiency of the best state of the art diesel conventional combustion can be maintained. It opens a promising way to future powertrain engines mixing the highest efficiency of the diesel engines with the near zero emission capability of the gasoline engine.