Study On The Combustion Characteristics Of N-Pentanol/Diesel Blends Droplet In Static And Turbulent Environments

The physical and chemical properties of n-pentanol are close to diesel fuel,so these two fuels can be mixed in any proportion.The n-pentanol is regarded as one of the most promising next-generation diesel alternative fuels,which can improve diesel emissions as a result of its higher vaporization potential heat and oxygen content,and can be produced through biological means such as microbial fermentation and glucose synthesis for sustainable use.Therefore,carrying out an in-depth study on n-pentanol-diesel and summarize its combustion characteristics is of great significance for reducing the external dependence of petroleum and the level of pollutant emissions in China.Based on the static environment single droplet test device,a set of turbulent environment single droplet test device was set up.By adjusting the speed of the eight fans built into the heating chamber,the environment of different turbulence intensities could be created.The strength of the OH*(hydroxyl)signal during droplet combustion in turbulent environments were detected using an optical diagnostic device.In the static environment of 900 K temperature,the effects of different n-pentanol contents on the combustion characteristics of droplets were studied by using P0D100(0% n-pentanol,100% diesel,after the same),P25D75,P50D50,respectively.Then,in the static environment of 900 K,950 K,and 1000 K,the effects of different ambient temperatures on the combustion characteristics of P50D50 droplets were studied.Next,in the high-intensity turbulence environment with the fans speed of 1000 r/min,the effects of different n-pentanol contents on the combustion characteristics of the droplets were studied by using P0D100,P25D75,and P50D50,respectively.Finally,the effects of different turbulence intensities on the combustion characteristics of P25D75 droplets were studied under the three turbulence intensities of the fans’ speeds of 0 r/min,500 r/min,and 1000 r/min,respectively.The results show that in the static environment of 900 K temperature,with the increase of n-pentanol contents,the puffing strengths of the droplets increase gradually,the evaporation rate constants also increase,the self-combustion delay time and the life of droplets both firstly shorten and then extend.The temperature trends of the three kinds of droplets are the same.In the static environment,with the increase of ambient temperatures,the puffing strengths in the combustion phase of P50D50 droplets increase greatly,and the combustion rate constants also increase,while the self-combustion delay time and the life of P50D50 droplets both decrease significantly.And the time between the moment of temperature growth rate suddenly changing and the moment of combustion beginning also shorten.In a high-intensity turbulence environment,with the increase of n-pentanol contents,the puffing strengths of droplets increase,the evaporation rate constantsgradually decrease,the combustion rate constants increase,the peak of the flame standoff ratios increase,the self-combustion delay time and the life of droplets both increase.Shortly after the beginning of combustion,all these three kinds of droplets appear the temperature platform phenomenon.With the increase of turbulence intensities,the evaporation rate constants of P25D75 droplets gradually decrease,the self-combustion delay time firstly shorten and then extend,the life of the droplets greatly extend,and the maximum deflection angles of the flames greatly increase.Besides,the self-combustion delay times determined by the hydroxyl method are slightly earlier than by the image method.However,the general trends of the two kinds of results are the same when the changes in the environmental conditions.