超临界水临界区域判定方法研究

对超临界水在临界区域进行合理的判定和区域划分,对于深入理解超临界水在临界过渡区域的流动和换热相关特征具有重要的作用。本文分析了超临界水从拟液态区向拟汽态区过渡的过程中,其导热系数、动力粘度、定压比热和膨胀系数等相关参数的变化规律特征,并归纳了已有超临界水在临界区域的划分判定模型。分析结果表明,在临界过渡区域,超临界水的流动特征参数和换热特征参数均会发生一系列连续剧烈的变化;只有同时考虑超临界水的膨胀特性和最大比热特性,才能更加合理地对临界区域进行划分。在此分析基础上,本工作完善了超临界水的三区分析判定模型,得到了新的超临界水在临界区域的判定划分数据,并由此拟合得到了新的超临界水分区边界计算关系式。新的计算关系式的误差范围在±0. 3℃之内,满足计算分析的要求。

Study on Critical Region Determination Method of Supercritical Water

Reasonable determination and regional division of supercritical water in critical regions plays an important role in understanding the characteristics of supercritical water flow and heat exchange in critical transition regions. In this paper, the transition characteristics of supercritical water from the quasi-liquid state to the quasi-vapor state is analyzed, and the characteristics of the variation of the thermal conductivity, dynamic viscosity, constant pressure ratio and expansion coefficient are also discussed. The classification and decision model of supercritical water in critical region are summarized. The results showed that the flow characteristic parameters and heat exchange characteristic parameters of supercritical water have a series of continuous and drastic changes in the critical transition zone of supercritical water. The critical region of supercritical water can be divided more reasonably by considering the expansion property of supercritical water and the maximum specific heat characteristic. On the basis of this analysis, the three-zone analysis decision model of supercritical water is improved, and the data of the new supercritical water in the critical region are obtained. The boundary calculation equation of the new supercritical water area is obtained. It has an error range of ±0.3 °C, meeting the requirements of the calculation and analysis.