摘要
为了研究超超临界循环流化床锅炉水冷壁和超临界水冷堆堆芯子通道中工质水的流动传热规律和机理,在压力为21~32 MPa、质量流速为410~760kg·m-2·s-1、热流密度为150~430kW·m-2的参数范围内,对Φ30mm×5.5mm垂直上升光管中超超临界水的传热特性进行了无量纲参数分析和数值模拟研究。根据实验结果,讨论了比热容比、浮升力以及热加速效应对超超临界水传热的影响。结果表明,这些无量纲参数与换热系数不存在很强的单值性关系,当采用这些参数预测超临界流体传热时需要补充其他相关参数。数值模拟采用SSTk-ω模型,模拟结果与实验数据吻合度较高,证明了该模型具有较强的适用性,并且分析了超临界流体发生传热强化和传热恶化的物理机理,证实了边界层内的大比热容工质份额和浮升力作用分别是导致传热强化和传热恶化的主要原因之一。
To study the flow and heat transfer behaviors of the water in the water-cooled wall of an ultra-supercritical circulating fluidized bed boiler and the core channel of supercritical watercooled reactor,the heat transfer characteristics of ultra-supercritical water in aΦ30 mm×5.5 mm vertical upward smooth tube were investigated by both dimensionless parameter analysis and numerical simulation at the pressure from 21 to 32 MPa,mass flow rate from 410 to 760 kg·m^-2·s^-1,and heat flux from 150 to 430 kW ·m^-2.According to the experimental results,the effects of specific heat ratio,buoyancy and thermal induced acceleration on the supercritical water are discussed.The results show that there is no unique and strong relationship between the dimensionless parameters and the heat transfer coefficient,and when the dimensionless parameters are used to predict the heat transfer of supercritical fluids,other parameters need to be supplemented.The SSTk-ω model was used in the numerical simulation,and the simulation results are in good agreement with the experimental data,which proves the applicability of the model.The physical mechanisms of heat transfer enhancement and deterioration in supercriticalfluids were analysed.It is proved that the main reasons for the heat transfer enhancement and deterioration are the portion of fluid with large specific heat in the boundary layer and the buoyancy effect,respectively.
作者
曲默丰
梁梓宇
赵云杰
万李
杨冬
QU Mofeng;LIANG Ziyu;ZHAO Yunjie;WAN Li;YANG Dong(State Key Laboratory of Multiphase Flow in Power Engineering,Xi＇an Jiaotong University,Xi＇an 710049,China)
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2018年第7期52-59,共8页
Journal of Xi'an Jiaotong University
基金
国家重点研发计划资助项目(2016YFB0600201)
关键词
超超临界水
传热特性
浮升力
热加速效应
ultra-supercritical water
heat transfer
buoyancy effect
thermal acceleration effect
