Investigations On Combustion/Explosion Characteristics Of Biofuels(2-Methlyfuran,Ethyl Acetate,and Mixed Fuel(Ethyl Acetate/Acetone/Ethanol))

Biofuels have a promising future as the next-generation fuel substitute for fossil fuels because they are environmentally friendly and have other superior qualities over petroleum-based fuel.Moreover,they can be used as octane rating extenders in fossil fuels as well as a chemical.Recently,several studies have been completed to improve the quality of biofuel for commercial use.Some of these studies focused on fuel quality,whereas other investigations sought to examine the combustion characteristics.Despite the research progress on biofuel combustion characteristics,the combustion characteristics of most biofuels have not been completely explored.In this regard,this thesis investigated the combustion characteristics of biofuel candidates 2-methylfuran(2-MF),ethyl acetate(EA),and mixed fuel(EA+Acetone+Ethanol(Et OH))at elevated pressures and temperatures.This includes the investigations on laminar burning velocity(LBV),intrinsic flame instability,and explosibility of 2-MF,EA,and mixed fuel(EA+Acetone+Ethanol(Et OH)).Firstly,the LBV of 2-MF was studied at the pressure of 1,2,and 4 bar,temperature of363 K,and equivalence ratio of 0.7-1.4 using the constant volume method(CVM).The CVM data were compared with the numerical result and constant pressure method(CPM)data.Empirical LBV correlation which can be used to measure LBV up to 421 K and 8 bar was obtained for 2-MF.Moreover,the LBV of EA was measured at the pressure of 1,2,and 4 bar,temperature of 358,388,and 418 K,and the equivalence ratio of 0.8-1.4.The experimental LBV was obtained using the CPM and CVM(linear approximation and analytical two-zone).The linear approximation result was?11%higher than the analytical two-zone result.The CVM data was?24%higher than the CPM data.The CVM was used to obtained LBV at?11.2 bar.Lastly,the LBV of mixed fuel(EA+Acetone+Ethanol(Et OH))was investigated experimentally and numerically at the pressure of 1 bar and the temperature of 358 K.In conclusion,it was found that as the initial pressure increases the LBV decreases;however,the LBV increases as the initial temperature increases.Secondly,intrinsic flame instability and cellularity of 2-MF premixed flames were investigated experimentally and theoretically at 1,2 and 4 bar,363,393,and 423 K using the equivalence ratios of 0.7-1.4.The flame morphology indicated that the flame becomes unstable when cells appear on the flame.However,the flame becomes more unstable as the initial pressure and the equivalence ratio increase.The linear stability model with variable transport properties was used to determine the growth rate,critical radius and Peclet number of the unstable flame.The theoretical and experimental critical radius and Peclet number decreased as the equivalence ratio increased.Furthermore,EA premixed flame instability was investigated at 358 K,388 K,418 K and 1 bar,2 bar,and 4 bar and the equivalence ratio of0.8-1.6.The wrinkling factor of EA unstable flame was investigated and it was shown that the wrinkling factor increases as the Peclet number increases.A maximum and minimum acceleration exponent,fractal excess,and fractal dimension of?1.37,?0.27,and?2.27 and?1.07,?0.06,and?2.06 were obtained in the self-acceleration analysis of EA unstable flames.What's more,empirical correlation;Pe_c=52.31M_b+260.4,(6_(8)=0.047040⁽(-0.33466)(7⁾and(6₍₈₇₎=0.049590)⁽(-0.25775)(7⁾was obtained for EA instability analysis.Finally,the confined explosion characteristics of 2-MF were investigated at elevated pressures and temperatures of 1,2,3,and 4 bar,333,363,393,and 423 K and the equivalence ratio of 0.7-1.4.The study showed that the peak explosion pressure,the maximum pressure rise rate and the deflagration index increased as the initial pressure increased.On the contrary,the peak explosion pressure,maximum pressure rise rate and the deflagration index decreased as the initial temperature increased.Again,the explosion characteristics of EA/H₂/air was investigated at 1,2,and 3 bar and 358 K using hydrogen in air of 0%,4%,8%and 12%.The explosion pressure,maximum pressure rise rate,and deflagration index increased as the hydrogen fraction increased.