超临界二氧化碳压缩机非平衡冷凝研究进展

Research progress on non-equilibrium condensation of supercritical carbon dioxide in compressor

压缩机是超临界二氧化碳(S-CO_(2))动力循环系统的核心设备,其工作在S-CO_(2)的近临界区域,因此S-CO_(2)工质在压缩机内流动时易发生非平衡冷凝,影响系统性能与可靠性。压缩机内部的S-CO_(2)非平衡冷凝实验观测难度大,数值模拟复杂,相关S-CO_(2)压缩机设计经验也较为缺乏。本文结合近年研究成果,从研究方法、数学模型和实验研究等角度总结了目前S-CO_(2)非平衡冷凝的研究进展,指出了需进一步开展的研究方向,如改变喷管几何结构参数,从而改变成核区体积,以改变流体在亚稳态区的滞留时间;改进气体状态方程进而提高亚稳态区域热物性精度,从而准确进行数值模拟;在设计S-CO_(2)压缩机时,利用实验测得的Wilson线设定压缩机进口条件,构建新的安全边界等。

Compressor is the core equipment of supercritical carbon dioxide(S-CO_(2))power cycle system,which runs near the critical region of S-CO_(2).Therefore,the non-equilibrium condensation of S-CO_(2) is easy to occur when S-CO_(2) flows in the compressor,which affects the performance and reliability of the system.The experimental observation of S-CO_(2) non-equilibrium condensation in the compressor is difficult,the numerical simulation is complex,and the S-CO_(2) compressor design experience is also relatively lacking.Based on the recent research results,this paper summarizes the current research progress of S-CO_(2) non-equilibrium condensation from the perspectives of research methods,mathematical models and experimental studies.Moreover,it points out the further research directions,such as:changing the geometry parameters of nozzle to change the volume of nucleation zone,so as to change the residence time of fluid in metastable state;improving the gas equations of state to enhance the accuracy of thermophysical properties of the working fluid in metastable state,so that the numerical simulation can be carried out accurately;using the Wilson line measured in the experiment to set the inlet conditions of the compressor in the design of S-CO_(2) compressor,to construct a new safe boundary.