| Energy source and environment protection are main problems that humankindhave to face. At present, the main Energy source that human can utilize is multi-kindsfossil energy such as petroleum, natural gas and coal etc. But the fossil energy can notbe reproduced. It is highly possible to exhaust. Petroleum is the main fuel ofautomotive. With the number of automotive retain increasing, fossil energy sourcedecrease fleetly. This problem became the sixty-four-dollar question which not onlydamages strategic safety of the country but also restricts the development ofautomotive industry.Automobile is not only the most consumers of those sources, but also thelargest pollution resource of human environment. From 1970s, people started theresearched about how to control emission and improve economy of engine. Theenergy efficiency has been improved greatly, and the poisonous emission has beendecreased more than 90%. With the improvement of the increasing concern aboutenergy shortage and environmental protection, the limits that every countryconstituted about the emissions are more and more strict. This is a challenge task forthe engine user to decrease the poisonous emissions.Conventional engine include spark ignition engine and compression engine. Thecombustion of spark ignition engine is premixed homogeneous promulgationcombustion. The mixture is ignited by the spark. Due to the limits of thecharacteristic of gasoline and knock of the spark ignition engine, the he CompressionRatio (CR) in the spark ignition engine is small. This leads the decrease of the thermoefficiency and the formation of many Nitrogen Oxides (NOx) and unburned gases. Onthe other hand, the Spark ignition engine controls the load through the throttle, thisleads to the decrease of mechanical efficiency in the middle load. The Spark ignitionengine's energy efficiency is 70% of the counterpart in the Diesel engine. This is theinsurmountable limitation of the Spark ignition engine Diesel engine's combustion isdiffusing combustion. The mixture starts ignition at the end of the compression stroke.Because of the short time to form the mixture, the mixture of the fuels and air isn'thomogeneous. This leads to the formation of the high temperature flame region.Because the temperature of diesel engine is very high, NOX emission is vast. The leanof oxygen at flame region with high temperature and consistency of mixture leads tothe occurrence of a mass of PM and so there is a limit in the emissions of PM andNOX in diesel engine.Under this background, researchers make many studies in many fields to savepetroleum and to meet regulation of European Ⅴ and European Ⅵ. Although theresearch about combustion technique such as high -pressure common-rail fuelinjection system, pre-injection fuel system, lean charge stratified intake system andin-cylinder direct Injection system etc have make many evolvement, these techniquestill can not meet the new regulation. So researchers of engine begin to quest for anew way of combustion. They put forward the new concept of internal-combustionengine -Homogeneous Charge Compression Ignition (HCCI). The concept ofHomogeneous Charge Compression Ignition (HCCI) is a new combustion mode inwhich fuel and air have mixed in intake , and the mixture combustion begin to ignitewhen piston at TDC. The homogeneous charge compression ignition (HCCI) has thepotential to get high efficient and to produce low NOx. It's been the hottest topic inthe business in the world and this topic had been projected as the national importantbasic research project in our country in 2002.However, it experiences problems with cold start running at idle and high loadsthat together with controlling the combustion over the entire speed/load range limitsits practical application. A solution to overcome these problems is to operate theengine in 'hybrid mode'. So some researcher made mode change as a new researchdirectionThis paper had carried out experiment concerning the HCCI combustion ofethanol under the 973 national important basic research project——the research aboutthe boundary conditions of alcoholic fuels combustion and critical questionconcerning the fuel chemistry's control in harmony.The experiments about the transition between SI and HCCI and SI modes thispaper involved have been carried out in a single cylinder research engine whichequipped with a intake thermo-management system.The study was carried on a single cylinder diesel engine ZS1105.The enginewas operated in HCCI mode at low load , while at cold start and high load the enginewas operated in SI mode by making some modification such as compression rate,added ignition system, intake thermo-management system and mode transferequipment. In other word, we achieved SI-HCCI-SI mode transfer.The combustion boundary of HCCI was studied in this paper. We confirmedthe thin limit and thick limit of HCCI operation area and analyzed the consumptionperformance and emission performance. It is found that the producing of NOXdescends as quickly as lambda increase, but HC and CO increased. Transientresponsibility of combustion mode transfer between SI and HCCI was studied indifferent speeds, and found that there are transitory misfire when transfer occurred notonly at the thin limit but also the thick limit due to some low temperature gas, whichexist between the intake pore and heater, addition with the variety of intake state,those result in from one mode to other need undergo approximately two cycle'svariation. In the transfer process of HCCI-SI, there is a longer time cycle variationdue to temporarily misfire and parameter change when the mixture is become thickand before the ignition limit of SI combustion.This paper identifies that SI-HCCI-SI mode transfer can be achieved by usingintake thermo-management system.
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