Shock-tube study of the ignition and product formation of fuel-rich CH4/air and CH4/additive/air mixtures at high pressure
Shock-tube study of the ignition and product formation of fuel-rich CH4/air and CH4/additive/air mixtures at high pressure
复制标题
DOI：
10.1016/j.proci.2018.05.120
复制
发表时间：
2019
影响因子：
3.4
通讯作者：
J. Herzler;Yasuyuki Sakai;M. Fikri;C. Schulz
中科院分区：
文献类型：
--
作者：
J. Herzler;Yasuyuki Sakai;M. Fikri;C. Schulz
如果化学转化在内燃机（ICE）中作为多联产过程进行，则可以通过部分氧化从甲烷中生产高价值化学品，损失较小（Gossler和Deutschmann，2015年）。动力学模型没有得到充分的验证，非常丰富的燃料和高压条件下的相关过程。因此，富燃料的甲烷/（添加剂）/空气混合物的点火延迟时间进行了测量，在激波管在约30巴和600和1650 K之间的温度。正庚烷和乙醚被用作添加剂，以增加燃料的反应性，使多联产过程可以实现在内燃机在HCCI条件下，在较低的压缩温度。在λ = 2时，测量的点火延迟时间与文献中使用不同机制的模拟结果吻合良好。合成气（CO、H2）是这些条件下的主要产物（Sen等人，2016年）。为了生产高级烃，必须增加当量比。使用非常富燃料的混合物（λ = 10），因为这些混合物在反应期间的温度增加相当低（<450 K），使得后点火温度保持在烟灰形成的下限以下。只有正庚烷作为添加剂的混合物，点火延迟时间的测量值与模拟值吻合较好，其他混合物的点火延迟时间与所有机理都有很大的偏差。作为进一步的参数，以改善和验证的机制在λ = 10，点火后的产品分布进行了测定，通过在冷却阶段与快速打开的阀门和GC/MS分析取样。除H2和H2O外，主要产物为CO和C2 H2、C2 H4、C2 H6和C6 H6等高级烃。消耗的甲烷中大约一半的碳转化为CO，另一半转化为高级烃。通过模拟很好地预测了产物分布。
Higher-value chemicals can be produced from methane with small exergy losses by partial oxidation if the chemical conversion proceeds in an internal combustion engine (ICE) as a polygeneration process (Gossler and Deutschmann, 2015). Kinetics models are not sufficiently validated for the very fuel-rich and high-pressure conditions relevant for this process. Therefore, ignition delay times of fuel-rich methane/(additive)/air mixtures were measured in a shock tube at about 30 bar and temperatures between 600 and 1650 K.n-heptane and diethylether were used as additives to increase the reactivity of the fuel so that the polygeneration process can be realized in an ICE at HCCI conditions at lower compression temperatures. At ϕ = 2, measured ignition delay times agree well with simulations using different mechanisms from literature. Synthesis gas (CO, H2) is the main product at these conditions (Sen et al., 2016). For the production of higher hydrocarbons, the equivalence ratio must be increased. Very fuel-rich mixtures (ϕ = 10) were used because the temperature increase during the reaction of these mixtures is quite low (<450 K), so that post-ignition temperatures stay below the lower limit of soot formation. Only for mixtures withn-heptane as additive, good agreement of measured and simulated ignition delay times is found. The other mixtures show strong deviations with all mechanisms. As a further parameter to improve and validate the mechanisms at ϕ = 10, product distributions after ignition were determined by sampling in the cooling phase with a fast-opening valve and GC/MS analysis. Besides H2and H2O, CO and higher hydrocarbons like C2H2, C2H4, C2H6, and C6H6were detected as main products. About half of the carbon of the consumed methane is converted to CO, the other half to higher hydrocarbons. The product distributions are well predicted by simulations.