Experimental Study On An HCCI Engine Fueled With N-butanol

Environmental problem has always been a sensitive topic and emissions of internalcombustion engine are the main source of environmental pollution. Vehicle engines havecurrently the biggest quantity and the widest scope for use is internal combustion engines, andtheir combustion condition directly affects the vehicle performance and emission targets. Inorder to optimize the working process of vehicle engines and combustion mode, countriesaround the world go around research and application about new combustion technologies ofinternal combustion engines, seek better methods for energy saving and emission reduction.At the same time, new energy such as bio-fuels and alcohol ether are constantly being testedand used in internal combustion engines. Combustion models of traditional engines withflame propagation and strong air movement are accompanied by thermal diffusion orsubstance diffusion, high emissions and low thermal efficiency. The new combustion mode,homogeneous charge compression ignition (HCCI), achieves the goal of high efficiency andlow emission. HCCI is low temperature combustion and has good adaptability and efficiencyfor fuels, however, its combustion start and combustion phase are too hard to control and itsoperation range is relatively narrow. If we can solve technical problems about the combustionphase and operation scope, the application value of HCCI engine will be incalculable. Tocontrol the combustion start point and the expansion of the running, a two-cylinder dieselengine was modified. This paper studies alcohol fuel HCCI combustion characteristic bycontrolling the inlet temperature in120℃~160℃and the speed at900r/min~1200r/min in order to analyses performance of HCCI combustion and emissions for differentmixture concentration n-butanol.The n-butanol HCCI engine test bench uses PFI injection system for preparation ofhomogeneous mixture. The inlet system and exhaust system and fuel supply system arereliably modified. The preparation for the test includes installation of sensors, calibration ofthe check point and determination of injection time. The test results show that theinlet-heating is helpful to improve n-butanol HCCI engine combustion and reduce emission;with the increase of air inlet temperature, the peak in-cylinder pressure and the peak heatrelease rate increase, and temperature in-cylinder and ignition time are in advance, and the combustion duration shorten, and cyclical fluctuation reduces, HC and CO emissions reduce.Excess air coefficient of n-butanol has a large effect on combustion and emissions of HCCIengine; with the reduction of the excess air coefficient, peaks of in-cylinder pressure andpressure rise rate increase, and heat release rate and temperature in-cylinder increase, and thechange of ignition timing is not obvious but pressure peak moment is slightly ahead, and thecombustion duration shorten, and cyclic variations lessen, HC emission increase, the COemission reduce. With the increase of engine speed, the peak in-cylinder pressure, the peakheat release rate and the peak temperature become higher, the combustion duration changesslightly, cyclical fluctuation decreases, and HC emissions increase, CO emissions reduce.NOx emission is always low in the experiment. In addition, this paper also studies theindicated pressure and the indicated thermal efficiency of different concentrations of mixturein the inlet temperature range, and determines the operating range of n-butanol HCCI engine.