变负荷工况下并联管内超临界水脉动流动及换热特性  

Flow Instability and Pulsating Heat Transfer Characteristics of Supercritical Water in Parallel Two-channel Under Variable Load Condition

作　　者：王文毓 杨冬[2] 王林[1] 高林[1] WANG Wenyu;YANG Dong;WANG Lin;GAO Lin(Xi’an Thermal Power Research Institute Co.,Ltd.,Xi’an 710054,Shaanxi Province,China;State Key Laboratory of Multiphase Flow in Power Engineering(Xi’an Jiaotong University),Xi’an 710049,Shaanxi Province,China)

机构地区：[1]西安热工研究院有限公司,陕西省西安市710054 [2]动力工程多相流国家重点实验室(西安交通大学),陕西省西安市710049

出　　处：《中国电机工程学报》2024年第7期2710-2717,I0016,共9页Proceedings of the CSEE

基　　金：国家自然科学基金项目(52076172)。

摘　　要：为了避免流动不稳定现象对水冷壁安全运行产生严重的影响,该文通过实验研究机组变负荷过程中,并联水冷壁管内超临界水的脉动流动及其换热特性。以Φ25×3 mm的1Cr18Ni9Ti并联管为实验段,在压力23~30 MPa,质量流率0.05~0.2 kg/s,入口水温200~390℃,入口压降系数0~5.5,热流密度0~500 kW/m^(2)的范围设置不同实验组,通过增加实验段热负荷进行实验。通过实验观察到不同类型的脉动及其边界,记录通道内质量流率和压力的变化,得到壁面温度的振荡曲线,分析了脉动流动的规律以及脉动对换热的影响。结果表明:低频、Ⅰ类高频和Ⅱ类高频3种脉动随着热负荷的增大依次出现。低频脉动和Ⅱ类高频脉动分管参数和总体参数同相脉动,而Ⅰ类高频脉动是管间脉动,主管道的流量几乎不会波动。对于低频脉动,振幅和频率的增大都会使通道中低比热流体的含量增大,从而降低流体换热能力;对于高频脉动,振幅的增大会减弱边界层热阻,有利于换热;频率的增加加大了通道中流体之间的能量交换,抑制了管子与流体之间的换热。可知,流动不稳定现象具有复杂的换热特性,应尽量将运行工况设定在脉动边界以外。The pulsating flow and heat transfer characteristics of supercritical water in parallel water-wall tube are experimentally studied under variable load condition to avoid the serious effect of flow instability to water-wall tube.The material of the tubes is 1Cr18Ni9Ti.The size of the tube is φ25×3 mm.The scope of experimental parameters is as follows:pressure from 23 to 30 MPa,mass flow rate from 0.05 to 0.2 kg/s;inlet water temperature from 200 to 390℃,inlet pressure drop coefficient from 0 to 5.5,and heat flux from 0 to 500 kW·m^(-2).Different experimental groups are set up and the experiment is carried out by increasing the heat load of the experimental section.Different types of oscillations and their boundaries are observed through the test.The variation of mass flow rate and pressure in the channels are recorded.The oscillation curves of wall temperature are obtained.The influence of oscillation on heat transfer is analyzed.The results show low frequency,high frequency of type I and high frequency of type II appear successively with the increase of heat load.The low frequency pulsation and high frequency of type II are in the same phase with the overall parameters.The high-frequency pulsation of type I is the intertube oscillation.The increase of amplitude and frequency will increase the content of low-specific heat fluid in the channel for low-frequency oscillation.Moreover,the heat transfer capacity of the fluid will be reduced.For high-frequency oscillation,the increase of amplitude will weaken the boundary layer thermal resistance,which is conducive to heat transfer.The energy exchange between the fluids in the channel increases with the increase of oscillation frequency.The radial heat transfer between the tube and the fluid is inhibited.The study shows that the flow instability phenomenon has complex heat transfer characteristics.The operating conditions should be set outside the pulsating flow boundary.

关 键 词：流动不稳定性 脉动换热 超临界压力 

分 类 号：TK124[动力工程及工程热物理—工程热物理]