正庚烷/空气混合气最小点火能量及其影响因素

Minimum ignition energy of n-heptane/air mixtures and its affecting factors

利用定容弹燃烧系统对正庚烷/空气混合气的最小点火能量进行了实验测量,获得了不同初始条件下正庚烷/空气混合气的最小电火花点火能量。实验结果表明:正庚烷/空气混合气的最小点火能量随当量比的增大先减小后增大。对于初始压力为0.1MPa和初始温度为450K的混合气,最小点火能量在当量比1.1附近达到最小值,为0.390 4mJ。实验发现:正庚烷/空气预混气的初始压力和初始温度对最小点火能量有重要的影响,与对火焰传播速度的影响是一致的。分析表明,初始温度和初始压力无论是对最小点火能量还是对火焰传播速度的影响,都与混合气的化学反应速率密切相关,化学反应速率越快,火焰传播速度越大,最小点火能量越小。

The minimum ignition energy（MIE）at different conditions of n-heptane/air mixtures can be obtained by the experimentation in constant volume combustion bomb.The experimental results showed that：MIE decreased and then increased with the increase of equivalence ratio.When the equivalence ratio was 1.1,MIE reached the minimum value.At the condition of the initial pressure 0.1 MPa and initial temperature 450 K,MIE was 0.3904 mJ.Initial pressure and initial temperature of premixed gas had a major influence on MIE,and their effect was consistent with the effect on flame propagation speed.The impact of initial temperature and initial pressure on flame propagation speed and MIE is related to the chemical reaction rate of mixture,the faster reaction rate means the greater flame propagation speed and smaller the MIE.