状态方程对高温高压条件下燃料液滴蒸发计算的影响

摘要

This paper proposed a high pressure evaporation model and numerical simulation method for a single droplet on the base of real gas equation of state (EOS). The evaporation process of n-heptane drop-let in nitrogen was simulated. The influence of Redlich-Kwong (RK) EOS, Soave-Redlich-Kwong (SRK) EOS and Peng-Robinson (PR) EOS on the calculation of fuel droplet's evaporation was discussed. PR EOS shows good agreement with experimental data in vapor-liquid phase equilibrium ( VLE), thermophys-ical properties and the variation of droplet diameter. SRK EOS is close to the results of PR EOS in VLE, critical state of binary mixture and n-heptane's enthalpies of evaporation. But SRK EOS's calculation re-suits are smaller than that of PR EOS in thermophysical properties and evaporation lifetime of droplet. RK EOS's calculation results are obviously different to that of SRK EOS and PR EOS. The highest accuracy of high pressure evaporation model for a single droplet is the PR EOS, flowing by SRK EOS and RK EOS.%以实际气体状态方程为基础,建立了单个液滴的高压蒸发模型和数值计算方法,并对庚烷液滴在氮气中的蒸发过程进行了模拟计算.重点研究了RK、SRK、PR三种状态方程对高温高压条件下燃料液滴蒸发计算的影响.结果表明,PR方程在气液相平衡、热物性参数以及液滴直径变化历程的计算上都与试验数据有很好的一致性;SRK方程在气液相平衡、二元混合物临界点以及庚烷相变焓的计算上与PR方程的计算结果十分接近,但在热物性参数和液滴蒸发寿命的计算上相比于PR方程的计算结果偏小;RK方程的计算结果与SRK方程和PR方程相比均存在较大偏差.因此,对于建立单个液滴高压蒸发模型而言,PR方程的精度最高,SRK方程次之,RK方程的精度最差.