石蜡燃料的燃烧性能与其化学组成的关系

Relationship between Combustion Characteristics and Chemical Components of Paraffin Fuel

为了研究石蜡的燃烧性能与其化学组成之间的关系,针对54~#、58~#、62~#和66~#4种粗晶石蜡开展了气相色谱分析,并测试了4种石蜡的燃烧热和在氧气流中的瞬时退移速率,同时利用N ASA-C EA软件计算了4种石蜡燃料不同氧燃比下的能量特性。结果表明:54~#、58~#、62~#和66~#4种粗晶石蜡的平均分子式分别为C_(26.40)H_(54.80)、C_(27.59)H_(57.18)、C_(28.02)H_(58.04)和C_(32.11)H_(66.22),正构烷烃含量分别为92.79%、89.44%、88.36%和84.55%;平均碳数n越大、正构烷烃含量越小的石蜡其燃烧热越低;随着平均碳数n值的增大以及正构烷烃含量的降低,石蜡的退移速率降低。NASA-CEA程序计算得到4种石蜡的能量特性受其化学组成的影响很小,其最佳氧燃比均为2.7,对应的理论比冲约为354 s,绝热火焰温度约为3600 K。

Paraffin fuels are ideal energy for hybrid rocket engine owing to the characteristics of high regression rate. In order to study the relationship between the combustion characteristics and chemical components of paraffin fuel, the gas chromatography was car- ried out for 54#, 58#, 62# and 66# kinds of macrocrystalline paraffin fuels, and measured the combustion heat and the regression rate in the oxygen flow rate of these 4 kinds of macrocrystalline paraffin fuels. In addition, the energy characteristics of these macro- crystalline paraffin fuels at different oxygen fuel ratio were calculated using NASA-CEA software. The results show that the average molecular formulas of the 54#, 58#, 62# and 66#4 kinds of macrocrystalline paraffin were C2640 H54.80, C22.59 H57.18 , C28.02 H58.04 and C32.u H66.22 , respectively, and the percentage contents of the n-alkanes of the 54#, 58#, 62# and 66# 4 kinds of macrocrystalline par- affin were 92.79%, 89.44%, 88.36% and 84.55%, respectively. The bigger the carbon number as well as the less the percentage content of n-alkanes, the smaller the combustion heat of paraffin fuel. And the regression rates of paraffin fuels were reduced along with the increase of carbon number. According to the calculated results of NASA-CEA software, the theoretical specific impulse of paraffin fuels were decreased with the carbon number of paraffin increasing, and the adiabatic flame temperatures were increased with the carbon number of paraffin increasing, but these influences of the chemical components of paraffin fuels on the energy char- acteristics were insignificant. The optimum oxygen fuel ratio of 4 kinds of macrocrystalline paraffin were all 2.7, the theoretical spe- cific impulse were all about 354 s more than HTPB, and the adiabatic flame temperature were all about 3600 K less than HTPB.