Of Lean Gas Concentration On The Impact Of The Combustion Process Butanol

With the increasing of industrialization and modernization, as a developing country, energy crisis and environment pollution are two challenges of our country in vehicles and automobiles. The alternative fuel is a effective way to solve the both problems. Finding out an combustion process of the alternative fuels with higher heat efficiency and lower pollutant emissions has become a realistic problem in the face of researchers. In recent years, bio-butanol production method is a great breakthrough, and the physical and chemical characteristics of the n-butanol is the same as the gasoline. As a new alternative fuel for internal combustion engines, n-butanol has attracted much interest in the energy and transportation field over the last few years.Based on previous studies, the research presents a series of combustion experiments for n-butanol in the constant volume combustion bomb in order to better understand the combustion characteristics of n-butanol. The excess air coefficient is a control variable affecting combustion characteristics on the study. Through coherent controlling the combustion boundary conditions, relevant experiments whose pressure before ignition is 0.8MPa,1.2MPa and 1.6MPa, initial temperature is 150℃,200℃and 250℃, the excess air coefficient is 1.0,1.1,1.2,1.3,1.4,1.6 and 1.8 are carried out. Through the discussion of the combustion characteristic parameters including the combustion pressure, the rate of pressure rise, the combustion temperature, accumulated heat release, the rate of heat release, ignition delay and combustion duration, the effects of the excess air coefficient on combustion process is clarified. Experimental results show that near the theoretical air-fuel ratio, the combustion rate is the fastest accompanying with shorter combustion duration while the combustion pressure, pressure rise rate, the combustion temperature, heat release rate and accumulated heat release reach the maximum. With increase of the excess air coefficient between 1.0 and 1.8, in other words with the decrease of the air-fuel mixture the combustion pressure, pressure rise rate, the temperature, heat release rate and the heat release reduce. Simultaneously, the reaction rate decrease, the combustion timing is deferred and the combustion duration becomes longer.Secondly, the 3D numerical calculation algorithm and mathematical models of constant combustion bomb combustion process is introduced. Using FIRE developed by AVL, set up the geometric model, divide grid mesh to the constant volume combustion bomb, and confirm the selected mathematical models by the related tests. By means of realistic engine near the end of the compression stroke, combustion process with different boundary conditions, such as, initial temperature, initial pressure and excess air coefficient is simulated in the constant volume combustion bomb. Numerical results includes the combustion characteristic parameters as well as the fuel distribution, pressure distribution and temperature distribution within cylinder are obtained. At the same time, effects of the air-fuel mixture, initial pressure and initial temperature on combustion process of n-butanol by a constant volume combustion bomb are analysed.