The exergy loss characteristics of combustion processes under homogeneous-charge compression ignition (HCCI) and stratified-charge compression ignition (SCCI) conditions are numerically investigated by analyzing two-dimensional (2-D) direct numerical simulation (DNS) data. Two fuels, dimethyl ether and ethanol, together with the initial conditions of different mean temperatures, and levels of temperature and concentration fluctuations relevant to HCCI/SCCI conditions were investigated. It is found that the prevalent deflagration mode significantly decreases the maximum exergy loss rates and spreads out the exergy loss rate for all the cases regardless of fuel types, temperature regimes, and temperature and/or concentration fluctuations. The primary irreversible sources of exergy loss are also identified. The chemical reaction is found to be the primary contributor to the total exergy loss, followed by heat conduction and mass diffusion, regardless of the fluctuation levels. It is also found that the relative change of exergy loss due to chemical reactions, ${\text{EL}}_{\text{chemrel}},$ correlates strongly with the heat release fraction by deflagration. The maximum ${\text{EL}}_{\text{chemrel}}$ is found to be less than 10%. Chemical pathway analysis reveals that the exergy loss induced by low-temperature reactions, represented by the decomposition of hydroperoxy–alkylperoxy and the H-abstraction reactions of the fuel molecule, is much lower under the SCCI conditions than that under the HCCI conditions. Generally, the dominant reactions contributing to the exergy loss in the high-temperature regime are nearly identical for the HCCI and SCCI combustion. Key reactions, including the H${}_2$O${}_2$ loop reactions, the reactions of the H${}_2$–O${}_2$ mechanism, and the conversion reaction of CO to CO${}_2,$ $\text{CO}+\text{OH}={\text{CO}}_2+\text{H},$ are found to contribute more than 50% of the total exergy loss. Due to locally higher reactivities by temperature and concentration fluctuations inducing deflagration dominance, these reactions occur at a relatively higher temperature (1600 K–1900 K) compared with the homogeneous zero-dimensional cases ($\sim$1400 K), resulting in a net reduction in exergy loss.

通过分析二维（2-D）直接数值模拟（DNS）数据，对均质充量压缩点火（HCCI）和分层充量压缩点火（SCCI）条件下燃烧过程的火用损失特性进行了数值研究。研究了两种燃料（二甲醚和乙醇）以及不同平均温度的初始条件，以及与HCCI / SCCI条件相关的温度和浓度波动水平。发现普遍的爆燃模式显着降低了最大火用损失率，并且在所有情况下都分散了火用损失率，而与燃料类型，温度范围以及温度和/或浓度波动无关。还确定了本能损失的主要不可逆源。无论波动水平如何，化学反应被认为是造成总本能损失，热传导和质量扩散的主要因素。还发现由于化学反应引起的火用损失的相对变化，${\text{EL}}_{\text{开姆雷尔}}，$通过爆燃与放热分数密切相关。最大值${\text{EL}}_{\text{开姆雷尔}}$被发现小于10％。化学路径分析表明，在SCCI条件下，由低温反应引起的（以氢过氧-烷基过氧基的分解和燃料分子的H-抽象反应为代表）的火用损失要比HCCI条件下要低得多。通常，对于HCCI和SCCI燃烧，在高温状态下导致本能损失的主要反应几乎相同。关键反应，包括H${}_2$Ø${}_2$ 回路反应，H的反应${}_2$–O${}_2$ 的机理，以及CO向CO的转化反应${}_2，$ $\text{一氧化碳}+\text{哦}={\text{一氧化碳}}_2+\text{H}，$被发现占总火用损失的50％以上。由于温度和浓度波动引起的爆燃优势，局部反应性较高，与均匀零维情况相比，这些反应在相对较高的温度（1600 K–1900 K）下发生（$〜$1400 K），从而净减少了火用损失。