流体气液临界参数测量方法研究进展

Near-critical and supercritical fluids have excellent transport and thermodynamic properties and can be widely used in fields such as chemical engineering, environment, machinery, and thermal energy utilization. Since the thermophysical properties including fluid density will change substantially near the critical point, it is of great significance to accurately determine the critical point of the fluid, including critical temperature, critical pressure and critical density data, to guide the optimization of thermodynamic cycle and system component design. Currently, experimental measurement is the most direct way to obtain high-precision critical parameters. This article first outlines the theory of gas-liquid critical points, the current research status of critical parameters, and their typical application scenarios. Secondly, it summarizes the main measurement methods of critical parameters, including constant volume method, variable volume method, flow method, pulse heating method, density line midpoint law method, pressure-volume-temperature (p-V-T) relationship method, quasi-static thermal analysis method, and physical property method. The advantages and disadvantages, scope of application, accuracy and main research institutions of these methods are summarized. Finally, the challenges and future development trends of critical parameter measurement methods are discussed.