The carbon oxides (CO2 and CO) in the insulating oil of power transformers come from the thermal aging of cellulosic insulating paper; the CO2/CO ratio can reflect the aging state of cellulosic insulating paper. At present, the formation mechanisms of CO2 and CO in oil-immersed power transformers are still unclear. In this article, the ReaxFF reaction force field is used to simulate the thermal aging process of cellulosic insulating paper, and the main reaction pathways of CO2 and CO molecules formed by cellulose pyrolysis are obtained. The study finds that the amount of CO2 and CO generated is related to temperature. When the pyrolysis temperature continues to rise, the amount of CO2 generated shows a downward trend, while the amount of CO generated continues to increase, and the CO2/CO ratio continues to decrease. The simulation results are consistent with the previous experimental results. Through pathway tracking, it is found that the CO2 and CO molecules are mainly derived from certain specific atoms of cellulose molecules. The COSMO-RS module is used to analyze the change trend of the solubility of CO2 and CO in insulating oil with temperature. The results show that the solubility of CO2 and CO decreases with the increase of insulating oil temperature, which provides theoretical support for accurate application of carbon oxides aging evaluation index at different temperatures.

中文翻译：

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纤维素绝缘纸热老化过程中碳氧化物形成机制的研究


电力变压器绝缘油中的碳氧化物（CO2和CO）来自纤维素绝缘纸的热老化； CO2/CO比值可以反映纤维素绝缘纸的老化状态。目前，油浸式电力变压器中CO2和CO的形成机制尚不清楚。本文利用ReaxFF反作用力场模拟纤维素绝缘纸的热老化过程，得到了纤维素热解形成CO2和CO分子的主要反应路径。研究发现CO2和CO的产生量与温度有关。当热解温度继续升高时，CO2生成量呈现下降趋势，而CO生成量不断增加，CO2/CO比值不断降低。模拟结果与之前的实验结果一致。通过通路追踪发现，CO2和CO分子主要来源于纤维素分子的某些特定原子。利用COSMO-RS模块分析CO2和CO在绝缘油中的溶解度随温度的变化趋势。结果表明，CO2和CO的溶解度随着绝缘油温度的升高而降低，这为不同温度下碳氧化物老化评价指标的准确应用提供了理论支持。