Modeling and thermodynamic analysis of liquid carbon dioxide discharge process under backflow-style self-pressurization

• Published in: Applied thermal engineering Vol. 264; p. 125473
• Main Authors: Zhang, Quan, Qin, Bin, Xiong, Yu, Zhou, Naijun, Lu, Zhaijun
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2025
• Subjects: High-pressure CO2; Liquid medium feed; Self-pressurization; Thermal multi-zone model (TMZM); Tube heat exchanger; Liquid medium feed; Self-pressurization; Tube heat exchanger; Thermal multi-zone model (TMZM); High-pressure CO2
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2025.125473

[Display omitted] •A liquid CO2 discharge system under backflow-style self-pressurization is proposed.•A thermal multi-zone model is developed to describe the discharge process.•Thermodynamic analysis on the pressurization rate is carried out.•The effects of many initial conditions on the pressure evolution are discussed. For most CO2 applications, the feed of liquid CO2 with stable pressure is an issue that is gradually attracting attention. In this paper, a backflow-style self-pressurization scheme with simple configuration and high performance is proposed, aiming to prevent the pressure drops during the feed process. A thermal multi-zone model (TMZM) considering heat and mass transfer is developed to describe this process and validated against experimental results, showing an error of less than 4.56 %. In addition, a thermodynamic analysis method is proposed to quantitatively analyze the dominant mechanisms of the effects of key parameters on pressurization rate. Firstly, the evolutions of thermal properties, the proportion of heating rate, and the thermodynamic analysis under different discharge flow rate are discussed, respectively. Then the effects of heating rate and backflow rate, vapor superheating and liquid subcooling, initial pressure and initial density on pressure evolution are investigated comprehensively. The model results show that the backflow-style self-pressurization scheme can keep the pressure stable throughout the liquid CO2 discharge process (fluctuation range of 0.16 MPa) under appropriate initial conditions. In order to avoid the pressure dropping, the conditions of small subcooled degree of liquid, high filling mass and low initial pressure should be adopted. This research provides a reference for the design and optimization of liquid CO2 or other liquid media feed systems.