Study On Catalytic Ignition And Combustion Characteristics Of Ethanol In Micro Tube

With the rapid popularization of micro-electromechanical devices,the advantages of easy-to-carry and high energy density of micro-combustion systems have gradually been concerned.At present,most scholars mainly study gaseous fuels such as hydrogen and methane.Compared with gaseous fuels,liquid fuels have the advantages of being easy to carry and high energy density.Ethanol,as a sustainable and renewable liquid fuel,has less corrosiveness and energy.High density,high H/C ratio and other advantages,and ethanol is an oxidizing fuel,containing nearly 35%oxygen,can reduce particulates and nitrogen oxides from combustion,is a promising alternative fuel for gasoline.There are few studies on the micro-scale combustion of ethanol.This paper mainly takes ethanol as the research object,and conducts experimental research and numerical simulation research on the dynamic characteristics,catalytic ignition and combustion characteristics of ethanol,and provides experimental theoretical basis and experimental reference data for the application of ethanol in micro power systems.Catalytic complete oxidation kinetics of ethanol on Pt/ZSM-5 under oxygen-enriched conditions in a quartz tube burner with an inner diameter of 4 mm.Power-rate law model and Langmuir-Hinshelwood model were established to characterize the low-temperature depth of ethanol During the oxidation reaction,the kinetic parameters of ethanol oxidation were obtained.It was found that the adsorption capacity of ethanol on the catalyst surface was stronger than that of oxygen.In the way of wall surface heating and ignition,the ignition temperature,stable combustion temperature,ignition position and peak reaction area,conversion rate and heat dissipation loss of ethanol under different operating conditions such as equivalent ratio and inlet flow rate were studied.Studies have shown that as the equivalence ratio increases,the higher the ignition temperature of ethanol,the catalyst surface temperature during ethanol stable combustion increases first and then decreases?maximum stable combustion temperature when?=0.8?,and the lower the conversion rate during stable combustion of ethanol;as the flow rate increases,it catches fire The temperature first decreases and then gradually increases.When the ethanol is stably burned,the catalyst surface temperature first increases and then decreases,the ethanol conversion rate gradually decreases,and the heat dissipation rate decreases.As the flow rate increases,the location of the first fire and the position of the peak reaction are the outlet end of the catalytic bed moves.The ignition position is not equal to the peak reaction position.Under the conditions of?=1,the flow rate is 300mL·min^-1 and600mL·min^-1,the peak reaction area moves upstream after the ignition.Based on the kinetic parameters of Power-rate law obtained,a one-step reaction mechanism was constructed for numerical simulation of ethanol catalytic combustion.60mg of catalyst was arranged in burner A?catalytic bed length 40mm?,burner B?catalytic bed length 30mm?and burner C?catalytic bed length 20mm?,to obtain burners with different catalyst space densities.The results show that the length of the catalytic bed of burner A is the longest,the fuel stays in the catalytic bed for a long time,the upper limit of the steady combustion flow rate is the largest,and the temperature distribution is the most uniform,but the lower steady combustion limit is the largest,the reaction intensity is low,and the heat dissipation loss is relatively large;The catalyst length of burner B is moderate.In the case of high equivalent ratio,the upper flow rates of burners B and A are relatively close.They have a reaction intensity that is almost the same as that of C.When the flow rate is between 0.4-5m·s^-1,the burner B's The maximum temperature of the center line is the largest,and the reaction residence time is relatively long,and the heat loss is not large;the length of the catalytic bed of burner C is the shortest,the upper limit of the steady-state combustion flow rate is the smallest,the combustion reaction intensity is the highest,and the temperature distribution is the most uneven.