水平管内低质量流量超临界二氧化碳异常传热行为研究  

Study on abnormal heat transfer behavior of supercritical carbon dioxide at low mass flow rate in horizontal tube

作　　者：李延富 苏成杰 孙晓东 王成龙 宿诗雨 姜文全[2] LI Yanfu;SU Chengjie;SUN Xiaodong;WANG Chenglong;SU Shiyu;JIANG Wenquan(China Coal Group Shenyang Research Institute Co.,Ltd.,Fushun 113122,China;College of Petroleum Engineering,Liaoning Petrochemical University,Fushun 113001,China)

机构地区：[1]中煤科工集团沈阳研究院有限公司,辽宁抚顺113122 [2]辽宁石油化工大学石油天然气工程学院,辽宁抚顺113001

出　　处：《热力发电》2023年第6期73-80,共8页Thermal Power Generation

基　　金：国家自然科学基金项目(52006094);辽宁省教育厅科学研究经费项目(L2019024,LJKMZ20220725);中煤科工集团沈阳研究院有限公司升级改造项目(CSJ-2022-009)。

摘　　要：研究了水平管内低质量流量超临界二氧化碳(S-CO_(2))异常传热行为,采用Fluent软件模拟了水平管内低质量流量条件下S-CO_(2)传热过程,分析了加热和冷却条件的异常传热行为和热流密度对传热影响。结果表明:热边界条件为压力8 MPa、质量流率200 kg/(m^(2)·s)、热值比q/G=0.2 kJ/kg时,S-CO_(2)管内流动冷却过程中上、下壁面温度均沿程降低,在S-CO_(2)主流温度达到拟临界温度时,距离入口551.0 mm处上壁面换热系数出现突变峰值,该处传热强化;S-CO_(2)管内流动加热过程中上壁面温度均先沿程升高,而后下降至395 K后缓慢上升,下壁面温度短暂降温后缓慢升温,距离入口69.5 mm处上壁面传热系数出现谷值,该处传热恶化;热流密度的增大使加热条件下换热恶化程度加剧,但对冷却换热并无明显影响。由此可见,特征截面的热物性分布是导致出现不同换热行为的主要原因。最后,基于低质量流量条件、热物性及浮升力影响,构建了预测超临界强化传热关联式,为超临界流体换热设备的设计与运行优化提供理论指导。The abnormal heat transfer behavior of supercritical carbon dioxide(S-CO_(2))with low mass fluxes in a horizontal tube was studied,the S-CO_(2) heat transfer process in the horizontal tube under the condition of low mass fluxes was simulated with Fluent software,and the abnormal heat transfer behavior of heating and cooling conditions and the influence of heat flux on heat transfer were analyzed.The results show that when the thermal boundary conditions are P=8 MPa,G=200 kg/(m^(2)·s)and q/G=0.2 kJ/kg,the temperature of top and bottom walls in the S-CO_(2) tube decreases along the way during the flow cooling process.When the mainstream temperature of SCO_(2) reaches the pseudo critical temperature,the heat transfer coefficient of the top wall at 551.0 mm from the inlet has a sudden peak value,heat transfer enhancement occurs here.Under heating conditions,the temperature of the top wall first rises along the tube path,then drops to 395 K and then rises slowly.The temperature of the bottom wall drops briefly and then rises slowly.At the top wall 69.5 mm away from the inlet,the heat transfer coefficient has a valley value,and the heat transfer at this point deteriorates.The increase of heat flow density aggravates the deterioration of heat transfer under heating conditions,but has no obvious effect on cooling heat transfer.It can be seen that the thermal physical property distribution of the characteristic section is the main reason for the different heat transfer behaviors.Based on the low mass fluxes conditions,thermo-physical properties and buoyancy effects,a correlation equation for predicting supercritical heat transfer enhancement is constructed,which provides theoretical guidance for the design and operation optimization of supercritical fluid heat exchanger.

关 键 词：超临界二氧化碳 传热 异常传热行为 热流密度 传热关联式 

分 类 号：TK124[动力工程及工程热物理—工程热物理]