中文摘要：

本文对超临界CO2流体迅速降压过程的热力学机理方面进行探讨。对迅速降压中的CO2的亚稳态平衡特性进行分析，研究CO2过热液的成核机理。计算结果表明：在迅速降压过程中，CO2气化核心的临界半径和临界势垒都随着过热度的增加而迅速变小，当过热度为0．9K时，生成临界半径气泡的能量势垒约为0．1K时的1．2％；当过热度为0．5K时，能量涨落值基本与生成气化核心的临界势垒相当。

英文摘要：

In this article, the theory on the rapid depression process of supercritical CO2 fluid was investigated. The metastable characteristics of decompression CO2 in depression were analyzed and the nucleation mechanism in CO2 superheating liquid was explored. The calculation results of its thermodynamic model indicate that the radius and the potential barrier of critical bubble nucleus in the process are decreased rapidly with increasing of superheat degree. The potential barrier ratio is 1.2% when the critical bubble nucleus under the superheat degree of 0.9 K and 0.1 K. Energy fluctuation amplitude is approximately equal to the critical potential barrier when the superheat degree is 0.5 K.