Shock tube study of n-decane ignition at low pressures

Ignition delay times for n-decane/O2/Ar mixtures were measured behind reflected shock waves using endwall pressure and CH＊ emission measurements in a heated shock tube. The initial postshock conditions cover pressures of 0.09-0.26 MPa, temperatures of 1 227-1 536 K, and oxygen mole fractions of 3.9%-20.7% with an equivalence ratio of 1.0. The correlation formula of ignition delay dependence on pressure, temperature, and oxygen mole fraction was obtained. The current data are in good agreement with available low-pressure experimental data, and they are then compared with the prediction of a kinetic mechanism. The current measurements extend the kinetic modeling targets for the n-decane combustion at low pressures.

Experimental study of n-decane decomposition with microsecond pulsed discharge plasma

A highly-integrated experimental system for the plasma decomposition of fuels was built.Experiments were conducted in a flow reactor at atmospheric pressure and confirmed that n-decane could be cracked by large-gap dielectric barrier discharge under the excitation of a microsecond-pulse power supply. Alkanes and olefins with a C atom number that is smaller than10 as well as hydrogen were found in the cracked products of n-decane（n-C10 H22）. The combination of preheating and plasma decomposition had strong selectivity for olefins. Under strong discharge conditions, small molecule olefins were found in the products. Moreover, there was a general tendency that small molecule olefins gradually accounted for higher percentage of products at higher temperature and discharge frequency.

SOLUBILITIES OF CARBON DIOXIDE IN MIXTURES OF n-DECANE-n-HEXADECANE AND n-HEPTANE-TOLUENE

Solubilities of CO2 in binary mixtures of n-decane-n-hexadecane and n-heptane-toluenewere measured in a glass apparatus by a synthetic method.Henry’s constants at several temperaturesand solvent compositions were reported.While the Henry’s constants of CO2 in mixtures of decaneand hexadecane can be satisfactorily predicted by a simple linear interpolation,prediction of Henry’sconstants for CO2 in mixtures of heptane and toluene requires excess Gibbs energy of the solvent mix-tures.The standard thermodynamic functions of solution（ΔH0,ΔG0,and ΔS0）were reported.

Experimental investigation on n-decane plasma cracking in an atmospheric-pressure argon environment

In order to solve the problem of the difficulty of igniting and steadily propagating a continuous rotating detonation engine when using liquid hydrocarbon fuel, an experiment was carried out using a dielectric barrier discharge excited by a nanosecond power supply to crack n-decane, the single alternative fuel to aviation kerosene, in a pre-heated argon environment.By changing the voltages and the discharge frequencies, the concentrations of different components as well as a number of different species were acquired.The generating mechanism of olefins and alkanes together with their competition mechanism were acquired.The influence of the voltage on isomer products was also analyzed.The results demonstrate that the bond energy distribution and the species generating condition are the main factors affecting the formation of the products.With the increasing of voltage and discharge frequency, small molecule olefins, large molecular olefins, large molecular alkanes, small molecular alkanes, and hydrogen were detected, and in turn, their concentrations were also increased except for ethylene;what is more, when the voltage was increased over 8.5 kV, the n-butene converted to trans-butene, and the n-pentene converted to isoamylene.

Numerical investigation of pyrolysis effects on heat transfer characteristics and flow resistance of n-decane under supercritical pressure

Pyrolysis of hydrocarbon fuel plays an important role in the regenerative cooling process. In this article, a Two-Dimensional（2D） numerical model is proposed to investigate the pyrolysis effects on the heat transfer characteristics and flow resistance of n-decane under supercritical pressure. The one-step global pyrolytic reaction mechanism consisting of 19 species is adopted to simulate the pyrolysis process of n-decane. The thermophysical and transport properties of the fluid mixture are computed and incorporated into the numerical model for simulation. Comparisons between the current predictions and the open published experimental data are carried out and good agreement is achieved. In order to better understand the complicated physicochemical process, further investigations on the turbulent flow and heat transfer coupled with pyrolysis in a tube have been performed under various operating conditions. The results indicate that the pyrolysis intensively takes place in the high fluid temperature region. The occurrence of the heat transfer deterioration would lead to increasing n-decane conversion at the beginning of the heated section. It is found that the pyrolysis could improve the heat transfer deterioration and promote the heat transfer enhancement. Meanwhile, pyrolysis gives rise to an abrupt increase of flow resistance. The mechanisms of the physicochemical phenomena are also analyzed in a systematic manner, which would be very helpful in the development of the regenerative cooling technology.

An Improved Heat Transfer Correlation for Supercritical Aviation Kerosene Flowing Upward and Downward in Vertical Tubes

Correlations are crucial to the design of cooling channels employed in regenerative cooling systems for scramjets.In this paper,correlations for the aviation kerosene flowing upward and downward in vertical tubes are studied and discussed.Four existing correlations are assessed against the available experimental data.To further improve the prediction accuracy of the heat transfer behaviors of the supercritical aviation kerosene,a new dimensionless parameter(Qi)relevant to the heat flux is proposed and introduced into the construction of a new correlation.Verification shows that the new correlation is more accurate than existing correlations.

A Simplified Chemical Reaction Mechanism for Surrogate Fuel of Aviation Kerosene

n-Decane was chosen as a one-component surrogate fuel to investigate the combustion performance ofRocket Propellant-3（RP-3） aviation kerosene. Sensitivity analysis and the reaction-path mlalysis method were used tosimplify the detailed reaction mechanism of n-decane, and a simplified mechanism including 36 species and 62 ele-mentary reaction steps was obtained. Moreover, 38-step elementary reaction investigated in the reference was simu-lated in the paper. Numlerical simulation method was conducted for both the 62-step and the 38-step reaction me-chanisms using pre-evaporation combustion models. Simultaneously Bunsen bunter for the combustion of premixed,pre-evaporated RP-3 aviation kerosene was designed to verify the simplified mechanism, and the temperature and gascomponent concentrations in the axial and radial directions at different heights were measured. The experimental re-sults revealed that the reaction temperature and the CO2 concentration increased first and then decreased across thea：,：ial positions, but on the contrary for the O2 concentration. The temperature and the O2 concentration distributionsof experimental results are in good agreement with that of numerical simulation results for the 62-step simplifiedreactions, and the CO2 concentration distribution is in general agreement with the numerical data. But the 38-stepsimplified reactions can only predict the change trend for the important parameters which are mentioned above.Through the contrastive analysis for these two kinds of simplified reactions, the 62-step reactions can more accuratelysimulate the combustion characteristics of RP-3 kerosene. Aud n-decane can be used as a one-component surrogatefuel for RP-3 aviation kerosene.