Under the background of the"dual carbon"target,exploring the pathway of efficient geolog-ical storage and high energy utilization of CO2 is a hot issue in CO2 emission reduction research.Based on the multi-phase change characteristics of supercritical CO2and the safety,environmental protection and cost advantages in energy utilization,a new supercritical CO2 spiral tube heat exchanger for deep earth storage is proposed,and a numerical simulation model is established.A heat transfer scheme with water as the heat-carrying fluid is designed for CO2 at 5 C.A study has been made of temperature,pres-sure,and thermal stress coupling changes of supercritical CO2 in a spiral heat exchanger under different water temperatures.The results show:As the temperature of the hydrothermal fluid increases,the heat-ing rate of supercritical CO2 is directly proportional to the water temperature,and the CO2 output tem-perature is positively correlated with the temperature of the hydrothermal fluid;compared with the heat transfer efficiency of CO2,the heat transfer efficiency of hydrothermal fluids is slower due to the influ-ence of CO2 phase change heat absorption,and the heat transfer of hydrothermal fluids is directly pro-portional to temperature changes;as the initial water temperature increases,the rate of CO2 phase change significantly increases,the flow rate has a significant impact on the heat absorption of CO2 phase change,and the volumetric flow rate of the hydrothermal fluid is negatively correlated with the temperature change of CO2;the dissipation temperature of hydrothermal fluids is directly proportional to the CO2 endothermic temperature due to the influence of CO2 heating and heat absorption.When the pipe diameter and inlet pressure is constant,100 ℃ hydrothermal fluid and supercritical CO2 heat transfer can achieve the CO2 phase change heat absorption requirements.The effectiveness and conven-ience of the spiral tube heat exchanger for hydrothermal fluids are verified through experiments,and the research provides a guideline for the design of supercritical CO2 spiral heat exchanger.
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