421 / 2018-12-27 13:26:16

罐体直径对斜温层储水罐内流动传热特性影响的数值研究 Effect of tank diameter on flow and heat transfer characteristics in stratified thermocline water storage tanks: A numerical study

斜温层储水罐;热电解耦;储能;罐体直径;数值研究 Stratified thermocline water storage tank; Heat-power decoupling; Energy storage; Tank diameter; Numerical study

全体主题 > 储能

摘要：合理的布水器结构有利于斜温层储水罐内斜温层的形成和增长，从而间接提升热电解耦的能力。本文基于计算流体力学（CFD）对采用了一种新型布水器的斜温层储水罐（高度41.4m）内部在不同直径下的流动及传热特性进行了数值研究。基于k-ε湍流模型研究了长达4小时的放热过程中斜温层的运动和增长。从速度分布中可以发现在入口布水器和出口布水器的周围存在旋涡。其中，靠近入口布水器的旋涡随放热过程的进行不断增长，靠近出口布水器的旋涡随放热过程的进行先增长后收缩。在初始给定一个厚度极薄的斜温层的前提下，获得了罐体直径对温度分布和斜温层厚度的影响规律。结果表明，该布水器可以有效维持斜温层的匀速上升。在放热过程中，斜温层厚度增加，且增长速率越来越小。在相同的入口流量和放热时长下，斜温层厚度随罐体直径的增加而减小。本文的研究结果可为同类型斜温层储罐的操作提供指导，并为设计者提供降低斜温层厚度方法的参考。
Abstract: The ability of stratified thermocline water storage tank in power plant units to decouple heat and power partly depends on the formation and growth of thermocline, which is closely linked with the structure of diffuser. In this paper, flow and heat transfer characteristics in 41.4 meters high stratified thermocline water storage tank of different diameters with a new type of diffuser were investigated numerically based on the computational fluid dynamics (CFD). The k-ε turbulence model was used to describe the motion and growth of thermocline during a discharging process of 4h. Swirl flow near diffusers was observed from velocity profiles. The size of the swirl flow near the inlet diffuser increases with discharging duration, while the size of the swirl flow near the outlet diffuser increases first and then decreases. With an initial thermocline thickness near to zero, the influence rules of tank diameter on the temperature distribution and thermocline thickness were obtained. The results show that the diffuser with new structure effectively preserves the vertical motion of thermocline with a constant speed. During the discharging process, the thickness of thermocline increases continually, while the increase rate decreases continually. In addition, the thickness of thermocline increases with the decreasing of the tank diameter for the same inlet flow and discharging duration. The results from this work may be of interest to operators attempting to obtain more information in analogous stratified thermocline water storage tanks and provide the designers of water storage tanks with references about methods of decreasing the thickness of thermocline.