Supercritical CO₂ Brayton cycles have become a research hotspot in high-efficiency power production. Adoption of other gas into CO₂ is proved to be an effective way to improve the performance of supercritical CO₂ cycle. In practice, it is inevitable to mix impurity gas into CO₂. The additive gas would have significant effects on isobaric heat capacity of CO₂ system. However, the lack of isobaric heat capacity of CO₂ mixture gas over supercritical regions of CO₂ poses a challenge in the design and optimization of supercritical CO₂ Brayton cycle.

In this work, N₂ and Xe, whose mole fraction ranges from 1% to 50 %, is considered as an additive gas in CO₂. The isobaric heat capacity of pure CO₂, CO₂/Xe and CO₂/N₂ binary mixture is calculated via molecular dynamics simulation. Compared to the commonly utilized database REFPROP, it is found that molecular dynamics simulation exhibits comparable and acceptable performance in prediction of the isobaric heat capacity of the mixed CO₂ system. The absolute average deviate of isobaric heat capacity of pure CO₂ and CO₂/N₂ binary mixtures is less than 1% and 1.3 % compared to the REFPROP database, respectively. Then, the effect of the Xe and N₂ on the isobaric heat capacity is discussed. The results demonstrated that the isobaric heat capacity would decrease continuously when CO₂ is mixed with Xe and N₂. The prediction models and data put forth in this paper offer great values for practical application system involving S-CO2 Brayton cycle.

超临界CO ₂布雷顿循环已成为高效发电的研究热点。事实证明，采用其他气体进入CO ₂是提高超临界CO ₂循环性能的有效途径。在实践中，不可避免地会在CO _{2 中}混入杂质气体。添加气体会对CO ₂系统的等压热容产生显着影响。然而，由于缺乏的CO的同量异位的热容量₂在CO的超临界区域混合气体₂的姿势在超临界CO的设计和优化一挑战₂布雷顿循环。

在这项工作中，N ₂和Xe 的摩尔分数范围从1% 到50%，被认为是CO _{2 中的}一种添加气体。通过分子动力学模拟计算纯CO ₂、CO ₂ /Xe 和CO ₂ /N ₂二元混合物的等压热容。与常用的数据库REFPROP相比，发现分子动力学模拟在预测混合CO ₂系统的等压热容方面表现出可比和可接受的性能。纯CO ₂和CO ₂ /N ₂的等压热容绝对平均偏差与 REFPROP 数据库相比，二元混合物分别小于 1% 和 1.3%。然后，讨论了 Xe 和 N ₂对等压热容的影响。结果表明，当CO ₂与Xe 和N ₂混合时，等压热容会不断降低。本文提出的预测模型和数据对涉及S-CO2布雷顿循环的实际应用系统具有重要价值。