Combustion Characteristics Of Biomass-based Cycloalkanes And Their Mixing With RP-3 Aviation Oil

At present,commercial biomass-based jet fuel lacks naphthenes and aromatics components and must be mixed with traditional jet fuel.A large number of researchers are committed to using lignin to prepare bio-based cycloalkanes to replace the cycloalkanes in traditional aviation oil,so as to achieve a full biomass based aviation oil.However,the research on which structure of cycloalkanes is most suitable for blending aviation fuel is not enough.Aiming at this problem,this paper takes biomass-based cycloalkanes as the research object,and simplifies the combustion process of aviation fuel in aviation engine step by step into three processes: thermal cracking,endothermy coking,low temperature ignition combustion and high temperature and high pressure combustion.Based on the existing experimental platform,the combustion characteristics of bio-based cycloalkanes and their mixtures with aviation oil were studied,which guided the directional preparation of cycloalkanes from lignin.The pyrolysis characteristics of biomass-based cycloalkanes with different structures at850 K were studied.It was found that the pyrolysis products were mainly olefin,cyclohydrocarbon and aromatic hydrocarbon,and decalin and ethyl cyclohexane were coking products such as indene.Side chain and polycyclic hydrocarbon structure contribute to thermal cracking of cycloalkanes and improve their heat absorption capacity,but also easily lead to coking,while 2-methylcyclohexane shows excellent performance,has better heat absorption capacity and low coking characteristics.The low temperature ignition reactivity of biomass-based cycloalkane mixture fuel was studied by low temperature combustion experiment.Based on the strongest to weakest combustion activity,the sequence was as follows: decalin > ethyl cyclohexane > cyclohexane >cyclopentane.Among them,the mixture of 20% and 30% decalin can significantly improve the ignition reactivity of the mixed fuel,which has a promoting effect,while the mixture of ethyl cyclohexane and jet fuel with different proportions has little difference in ignition reactivity,and even the mixture of cyclohexane and cyclopentane with 10% will weaken the ignition reactivity of the fuel.Reaction mechanism Analysis Side chain structure and double ring structure can improve the ignition reactivity of fuel,and the longer the side chain length,the more obvious effect.Therefore,decalin and long-side chain alkanes have better performance in low temperature ignition reactivity.The spray characteristics and high temperature and high pressure combustion characteristics of biomass-based cycloalkanes and mixed fuels were studied in a constant volume combustion laboratory.The spray results show that under high injection pressure and high temperature and high pressure,mixing decalin will reduce the spray effect of mixed fuel.The spray characteristics of methylcyclohexane,cyclohexane and cyclopentane are similar to those of jet fuel.Biomass combustion characteristics of high temperature and high pressure show that the four kinds of structure base naphthene will extend the reactive blends ignition and flame length of the float,decalin and methylcyclohexane less when mixing proportion of10%,although to a certain extent reduces the ignition quality,but can reduce carbon smoke emission,and after blending 20%,ignition quality drop more,unfavorable to burn.However,the mixture of cyclohexane and cyclopentane is not conducive to high temperature and high pressure combustion of mixed fuel.In summary,based on the spray and combustion characteristics of biomass-based cycloalkanes,it is suggested that the main product groups of biomass-based cycloalkanes prepared from lignin can be divided into polycyclic structures such as decalin and monocyclic hydrocarbons with more and longer side chains...