Exergetic analysis of reactive systems for polygeneration

本子项目设计了富燃料HCCI发动机的工艺概念，用于功、热和有用化学品的多代发电，并对其进行热力学和燃烧经济性评估。同以前一样，有用化学品方面的重点将放在合成气和高价值碳氢化合物如乙烯和乙烯上。由于甲烷/空气混合物自燃缓慢，添加剂和通过废气再循环或回收的方式预热新鲜气体起着重要作用。在前期的项目中，反应性添加剂如正庚烷和二甲醚的积极作用得到了证明。这主要是由于降低了HCCI发动机中甲烷点火所需的入口温度。然而，相当一部分的能量和碳是由添加剂引入的。因此，替代添加剂，如臭氧，是有趣的，在低得多的浓度下也有活性。现在将在拟议的项目期间对这些问题进行调查。在初步研究中，有实例表明，即使在燃料丰富的范围内，极少量的臭氧也能在降低的温度下点火。因此，现在的目标是通过模拟来量化富燃料范围内甲烷和乙醇与臭氧混合物的发动机动力学和热力学。一方面，有必要揭示压缩膨胀循环中富燃料范围内臭氧量、反应中间体和最终产物之间的相关性。另一方面，目的是为发动机多联产找到切合实际的参数范围，也考虑到压力上升率和燃烧相位。最后，发动机过程的质量，也与实验子项目合作，将通过火用概念进行评估，以减少不可逆性。由于发动机过程只能被视为一个子系统，因此关于其热力学质量的结论很重要，但也必须与上游和下游过程步骤一起考虑，同时考虑热力学和经济因素。发动机多联产是否会被使用，最终取决于与竞争转换方法相比的总成本和能源和化学产品的价值。对能源破坏成本和投资成本的努力经济考虑提供了关于改进可能性的重要信息。到目前为止，基于发动机的多电联产工艺作为一个整体系统在热力学和经济上也是有利的，但弱点也被发现。该项目的目的是开发工艺概念，包括材料分离和能量集成，用于有前途的臭氧添加电机条件，并将其与其他概念进行比较。

This subproject designs process concepts for the use of fuel-rich HCCI engines for the polygeneration of work, heat, and useful chemicals and evaluates them thermodynamically and exergoeconomically. As before, the focus with regard to useful chemicals will be on synthesis gas and higher-value hydrocarbons such as ethyne and ethene. Due to the slow auto-ignition of methane/air mixtures, additives and preheating of the fresh gas by means of exhaust gas recirculation or recuperation plays an important role. In the preceding project period, the positive effects of reactive additives such as n-heptane and dimethyl ether were demonstrated. These are mainly due to the reduction of the inlet temperature required for methane ignition in HCCI engines. However, a substantial part of the energy and carbon is introduced by the additive. Therefore, alternative additives, such as ozone, are interesting, that are active at much lower concentration. These will now be investigated in the proposed project period. In preliminary studies it was exemplarily shown that very small amounts of ozone enable ignition at reduced temperature even in the fuel-rich range.Therefore, it is now aimed to quantify the engine kinetics and thermodynamics of methane and ethanol mixtures with ozone in the fuel-rich range by means of simulations. On the one hand, it is necessary to uncover correlations between ozone quantity, reactive intermediates and end products for the fuel-rich range in compression-expansion cycles. On the other hand, the aim is to find realistic parameter ranges for engine polygeneration also with regard to pressure rise rates and combustion phasing. Finally, the quality of the engine process, also in cooperation with the experimental subprojects, is to be evaluated by means of the exergy concept, in order to reduce irreversibilities.Since the engine process can only be regarded as a subsystem, conclusions about its thermodynamic quality are important, but must also be considered together with upstream and downstream process steps, both applying thermodynamic and economic considerations. Whether engine polygeneration will be used, depends ultimately on the total costs and the value of the energy and chemical products compared to competing conversion methods. The exergo-economic consideration of the costs of exergy destruction and the investment costs provides important information about possibilities for improvement. So far, it has been established that the engine-based polygeneration process is also thermodynamically and economically advantageous as an overall system, but weak points have also been uncovered. The aim of this project is to develop process concepts including material separation and energy integration for promising motor conditions with ozone addition and to evaluate them in comparison to alternative concepts.