热化学反应过程㶲损机制及调控方法研究

Exergy Destruction Mechanism and Regulation Methods During Thermochemical Reactions

摘要

新一代能源动力系统注重将物理能梯级利用原理拓展到化学能转化过程,以实现物质化学能的有效利用.本文进一步探讨了化学能梯级利用的基本原理,明晰了热化学反应过程㶲损与驱动化学反应进行的“势”(化学势)、反应体系自由能的关系,揭示化学反应㶲损本质:化学势驱动下系统自由能降级为低品位热能.基于此,以燃料分阶段燃烧降低反应㶲损为切入点,阐明化学反应在能量转化过程中所承担的角色,提出了减少热化学反应过程㶲损的路径调控原则,并以甲醇分阶段燃烧为例开展㶲分析进行论证.研究发现:耦合甲醇裂解的分阶段燃烧过程使得化学能与释热热能平均品位差由 0.35 降至 0.23；吸热反应热源温度在 510～580 K 时,㶲收益可达 18%以上.研究为热化学过程低㶲损路径设计提供了理论依据与调控原则.

Abstract

To achieve the high-efficiency utilization of fuel chemical energy, the new generation of energy power systems pays attention to extending the cascade utilization of physical energy to that of chemical energy associated with fuel conversion. In this study, the basic principles of chemical energy cascade utilization are further explored. The relationship between exergy destruction during thermochemical reaction and the chemical potential (or the free energy) is clarified. This reveals the essence of exergy destruction: the free energy degrades into low-grade thermal energy. On this basis, by analyzing the mechanism of reducing exergy destruction during staged combustion process, the role of chemical reactions during energy conversion is elucidated, and the reaction path regulation principles for minimizing irreversibility are proposed. Finally, the case study of methanol indirect combustion is conducted to demonstrate the basic insights of the current study. Results indicate that staged combustion coupled with methanol decomposition can reduce the average energy level difference between chemical energy and thermal energy from 0.35 to 0.23. When the heat source temperature ranges from 510 K to 580 K, the exergy destruction decreases by over 18%. This study provides theoretical guidance and regulation principles for designing low-energy-loss pathways in thermochemical process.

关键词

㶲损 / 化学反应 / 梯级利用 / 自由能

Key words

exergy destruction / chemical reaction / cascade utilization / free energy

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基金资助

中国华电集团有限公司科技项目(65-XJGS/HD-BYGS-2024-DTZX01)