Structure Design Of Jet Stirred Reactor Based On The Study Of Fuel Oxidation Characteristics

The jet stirred reactor is important experimental device for studying the process of fuel oxidation and thermal decomposition.It is mainly applicable to the study of gas phase kinetics and its biggest advantage is that it has a highly efficient gas-phase mixing efficiency,which makes the gas composition in the reactor uniform.Based on the classic JSR structure,a JSR experimental device was designed and its internal temperature field inhomogeneity was evaluated.Based on the classic inclined JSR structure,this study obtained the residence time distribution curve and cumulative distribution function curve by using CONVERGE software,and compared them with the theoretical curve to verify the accuracy of this model.Then the mixing homogeneity of gas in a JSR with different nozzle diameters and reactor radii was analyzed at both macro and micro scales.According above results,a JSR experimental device was designed and the methane oxidation experiments were carried out under lean combustion,chemical equivalent and rich combustion conditions respectively.The accuracy of data measurement of the experimental device was verified by comparing with the experimental data in the literature and the PSR module simulation data of CHEMKIN software.Then,a three-dimensional model of methaneoxygen-nitrogen flow and oxidation within JSR was established based on CONVERGE software.According to the above experimental data,the temperature field and component concentration calculated by the 3D calculation model are verified.Finally,based on the 3D simulation results of JSR,the global and local temperature field inhomogeneity and the causes of temperature field inhomogeneity were analyzed,and some suggestions were put forward.The results indicate that Results show that the residence time distribution curve and the cumulative distribution function curve are consistent with the theoretical model curve when the JSR nozzle diameter is 0.2 mm.Under the condition of the same average residence time,the small-diameter nozzle can obtain a higher gas injection velocity,and thus a greater turbulence intensity and penetration depth,which can obtain a good gas mixing uniformity and obtain a more ideal effect.The mixing uniformity can reach more than 0.999.At the same time,the value of its microscopic mixing state is 59,greater than 30,and the microscopic mixing state is good.Simulation results also show that the carbon dioxide concentrations in the central of reactor is higher than that near the wall of reactor.The carbon dioxide in this area has a longer residence time.In the same period,the proportion of carbon dioxide flowing out of the reactor is larger when the radius of the spherical reactor is small.It can be considered that under the condition of smaller reactor diameter,the degree of "dead cycle" of gas is lower and more similar to the ideal state.Based on this,the JSR geometry(The nozzle diameter is 0.2 mm and the spherical reactor radius is 20 mm)can predict the residence time distribution curve and cumulative distribution function curve accurately when the average residence time is 0.5 s,0.8 s and 1.0 s.The experimental data obtained from the experimental device based on this structure are also well consistent with the experimental data in the literature and the simulation data of PSR module.The reliability of the experimental device is fully demonstrated.The results show that maximum absolute error is 4.6 K and the relative error is only 0.4% in prediction of temperature based on the 3D model of methane oxidation.As for the component concentration,the relative error of oxygen mole fraction is the largest when the equivalent ratio is 0.5,which is 13.6%,and the others are within 10%.Considering the inevitable systematic error such as the accuracy of gas chromatograph,the calculation accuracy of the 3d model established in this study is acceptable.