Supercritical CO₂ Brayton cycle has been highly recommended as a promising power cycle. As a method to improve the cycle performance, some trace gases could be introduced in the system. Due to rare viscosity coefficient data of CO₂-based mixtures over the supercritical regions of CO₂, the effect of trace gas on the characteristics of pressure drop has not been clarified yet. Thus, it leads to a challenge in the design and optimization of the supercritical CO₂ Brayton cycle when mixing working fluid is considered.

In this work, microamount Xe, the mol fraction of which ranges from 1 % to 5 %, is considered as an additive gas. The viscosity coefficient of CO₂-Xe was calculated using molecular dynamics simulation. A reliable simulation strategy for the viscosity coefficient calculation was formed, which was proved available since the average relative error of the simulated viscosity coefficient of pure CO₂ is around 1 % compared to the REFPROP database. Then, the influence of the addition of Xe on the viscosity coefficient and the pressure drop of the recuperator was discussed. The results demonstrate that the viscosity coefficient would change a lot when CO₂ is mixed with Xe. A relative change of viscosity coefficient of 66 % can be observed. Consequently, the pressure drop of the recuperator could enlarge a lot reaching up to 12 %. This work suggests that attention must be paid to the changed viscosity during the design for a reasonable prediction when the trace gas is introduced into the system.

极力推荐超临界CO ₂布雷顿循环作为有希望的功率循环。作为改善循环性能的一种方法，可以将一些微量气体引入系统中。由于CO的稀有粘度系数数据₂在CO的超临界区域系混合物₂，痕量气体的压降的特性的影响尚未被阐明。因此，当考虑混合工作流体时，这在超临界CO ₂布雷顿循环的设计和优化方面带来了挑战。

在这项工作中，其摩尔分数为1％至5％的微量Xe被视为添加气体。使用分子动力学模拟计算CO ₂ -Xe的粘度系数。形成了可靠的粘度系数计算模拟策略，由于与REFPROP数据库相比，纯CO ₂的模拟粘度系数的平均相对误差约为1％，因此可以证明该策略可用。然后，讨论了Xe的添加对同流换热器的粘度系数和压降的影响。结果表明，CO ₂引起的粘度系数变化很大。与Xe混合在一起。可以观察到66％的粘度系数的相对变化。因此，换热器的压降可能会扩大很多，达到12％。这项工作表明，在将微量气体引入系统时，在设计过程中必须注意粘度的变化，以进行合理的预测。