带有横向微槽道的超临界LNG紧凑式换热器换热强化模拟研究  

Simulated research of enhanced heat transfer characteristics of supercritical LNG compact heat exchanger with transverse micro-grooves channels

作　　者：赵星霖 王平阳[1] 黄佳卉 Zhao Xinglin;Wang Pingyang;Huang Jiahui(School of Mechanical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学机械与动力工程学院,上海200240

出　　处：《低温工程》2020年第6期1-8,共8页Cryogenics

基　　金：国家重点研发计划重点专项项目(No.2018YFC0310400)资助。

摘　　要：为了强化超临界LNG紧凑型换热器的换热强化能力,设计了一种应用3D打印技术制备的带有横向微沟槽群的微细流路,并进行了数值模拟验证和性能特性对比,以提高超临界流体LNG在紧凑式气化换热器中的强制对流换热性能。首先对光滑管道下不同流道截面形状对换热特性和流动特性的影响进行了数值计算,结果表明相同截面积下不同形状对超临界LNG的换热与流动特性基本无影响。然后讨论了在2 mm矩形流道带有最佳横向微沟槽群条件下,工质温度在120—250 K范围内两面开槽与四面开槽结构换热特性与流动特性的对比,进一步考察了工质温度、质量流量、进口压力对传热系数、摩擦因子和综合效益系数的影响。最后讨论了重力的影响。结果表明具有四面开槽的换热器综合换热效益得到40%左右的增加,与两面开槽相比并不是完全的两倍关系,微槽道构造显示了出色的换热强化综合效果。此外,对水平流动而言,在研究范围内重力作用会略微强化传热系数。当流动方向为竖直向上时,重力使换热加强,反之,重力将减弱换热。In order to enhance the heat transfer capacity of supercritical LNG compact heat exchanger,a kind of micro channel with transverse micro groove group prepared by 3D printing technology was designed,and numerical simulation verification and performance comparison were conducted to improve the forced convection heat transfer performance of supercritical fluid LNG in compact gasification heat exchanger.Firstly,the influence of different flow passage cross-section shapes on heat transfer and flow characteristics under smooth pipeline is numerically calculated.The results show that different shapes under the same cross-sectional area have basically no influence on heat transfer and flow characteristics of supercritical LNG.Then,the comparison of heat transfer characteristics and flow characteristics between two-sided and four-sided slotted structures with working medium temperature in the range of 120-250 K under the condition of 2 mm rectangular channel with the best transverse micro-groove group is discussed,and the influences of working medium temperature,mass flow rate and inlet pressure on heat transfer coefficient,friction factor and performance evaluation criteria are further investigated.Finally,the influence of gravity is discussed.The results show that the comprehensive heat transfer benefit of the heat exchanger with four slotted sides is increased by about 40%,which is not completely double compared with the two slotted sides,and the microgroove structure shows excellent comprehensive heat transfer enhancement effect.In addition,for horizontal flows,the heat transfer coefficient is slightly enhanced by gravity in the study area.When the flow direction is vertical and upward,gravity strengthens the heat transfer;otherwise,gravity weakens the heat transfer.

关 键 词：换热强化 强制对流 微通道 LNG 超临界流体 

分 类 号：TB611[一般工业技术—制冷工程]