油气燃料临界燃烧和超临界燃烧的基础理论

BASIC THEORY ON CRITICAL AND SUPERCRITICAL COMBUSTION OF OIL/GAS FUELS

利用热力学基本定律和常用状态方程vdWEOS、RKEOS、SRKEOS、PREOS及PGEOS,对CH4、C2H6、C3H8、C8H18、C16H34等的临界温度、临界压力、临界比容三者之间的相互关系进行了理论计算。还计算了He、H2、N2、O2、CO、CO2和水蒸气等的物性参数,并分别与其临界试验参数进行了对比分析。结果表明:理想气体状态方程PGEOS得到的结果最差,它对这些物质临界压力计算的平均误差高达260%以上,对临界温度计算的平均误差也在72%以上;而PREOS得到的结果最好,且对临界温度计算的平均误差不足0.2%,最大误差在0.6%以下,对临界压力计算的平均误差则小于0.8%;其余EOS对物质临界参数的描述则介于二者之间。其中:vdWEOS对这些物质临界压力描述的最大误差在60%以上,平均误差在14%以上;RKEOS和SRKEOS对临界压力描述的最大误差均在13%以上,平均误差在2.6%左右,但SRKEOS对临界温度的总体描述要好于RKEOS。因此,PGEOS不能用来表述这些物质临界参数之间的相互关系,而PREOS和SRKEOS可对这些物质临界参数之间的相互关系作出相对较好的描述。

With thermodynamic fundamentals and equations of state (EOS) of vdW EOS, RK EOS, SRK EOS, PR EOS and PG EOS, The physical parameters of critical temperature, pressure and specific volume is calculated theoretically for the major hydrocarbons such as CH4, C2H6, C 3H8, C8H18, C16H 34 etc. Also, the physical parameters of some major gases, such as He, H2, N2, O2, CO, CO2, and vapor etc., are calculated to make the demonstration and the study results referential-able. And all the parameters are analyzed and compared with their testing critical parameters respectively. The results show the result from PG EOS is the worst. The average error of the calculated critical pressures reaches more than 260% and the average error of the calculated critical temperatures is more than 72% for these substances. The result from PR EOS is the best. The average error of the calculated critical temperatures is less than 0.2% and the largest error is below 0.6%. The average error of the calculated critical pressures is less than 0.8%. The results from the other EOS are between the results from the above-mentioned 2 EOS. The largest error of calculated critical pressures from vdW EOS is above 60% and the average error is above 14%. All the largest errors of calculated critical pressures from RK EOS and SRK EOS are above 13% and the average errors about 2.6%. But the critical temperature calculated by SRK EOS is better than that by RK EOS. Therefore, PG EOS can't be used to describe the relationship of the critical parameters for these substances. But PR EOS and SRK EOS can describe the relationship of the critical parameters for these substances well. The conclusions provide necessary and basic theoretical base for study on critical and supercritical combustion of oil/gas fuels.