关键词: 二氧化碳, 管道泄漏, 热力学, 相变, Prandtl数

Abstract:

Three sets of industrial-scale dense phase CO₂ pipelines (length 258 m, inner diameter 233 mm) leaking experiments with different pore sizes (50, 100 and 233 mm) were carried out, and the time-history curves of CO₂ pressure and temperature at different positions in the tube were recorded. The change of CO₂ density, enthalpy value and Prandtl number (Pr) was obtained by using REFPROP software. The variation of thermodynamic characteristics of dense CO₂ pipeline leakage and pressure loss process was studied. The results show that after the pipeline leaks, the dense phase CO₂ is rapidly converted into gas-liquid two-phase. The gas-liquid two-phase is converted into the gas phase with the experiment, and the solid phase dry ice is formed. The phase change causes the median enthalpy value in the pipeline to increase, the density of the medium to drop sharply, and the smaller the diameter, the more obvious the parameter change. Since the medium in the pipeline forms a multi-phase flow fluid flow, the temperature change is closer to the top of the leak port, and the convective heat transfer intensity is greater. As the leakage diameter increases, the CO₂ phase changes significantly, Pr increases, and the heat transfer in the pipeline moves from the bottom of the pipeline to the top of the pipeline. The heat transfer effect inside the pipeline is the best at the critical point of the CO₂ phase transition.

Key words: carbon dioxide, pipeline leakage, thermodynamics, phase change, Prandtl number