轴向导热对板翅式换热器传热性能的影响  

Performance Evaluation of Plate-Fin Heat Exchanger Considering Effect of Axial Heat Conduction

作　　者：康蕊[1] 厉彦忠[1] 杨宇杰[1] 王哲[1] 司标[1] 郑捷宇 

机构地区：[1]西安交通大学动力工程多相流国家重点实验室,西安710049

出　　处：《西安交通大学学报》2017年第2期140-148,共9页Journal of Xi'an Jiaotong University

基　　金：国家科技支撑计划资助项目(2012BAA08803);教育部高等学校博士学科点专项科研基金资助项目(20130201i10069)

摘　　要：为了降低轴向导热对板翅式换热器传热性能的影响,利用计算流体力学软件Fluent,分别计算了考虑轴向导热模型和不考虑轴向导热模型的换热因子,引入无量纲参数传热恶化率(η)来评价轴向导热对板翅式换热器传热性能的影响程度,讨论了流体工况下翅片类型(平直翅片和锯齿翅片)、翅片结构、流体种类、翅片材料等因素对η的影响。计算结果表明,轴向导热对板翅式换热器传热性能的影响程度较大,流体工况下翅片类型、流体种类、翅片结构、翅片材料等因素对η均有所影响。其中,对于不同流体工况,当Re小于等于600时,η较大,此时在翅片的设计和选型时需要考虑轴向导热对其传热性能的影响;对于不同的翅片类型,在Re小于等于600时,锯齿型翅片的η低于平直翅片;对于不同翅片结构,无量纲参数β为70、翅片密度为4.1的此类平直翅片的η最大,在翅片选型时应尽量少选此类平直翅片;对于低温流体,Pr越大,其η越大;对于不同翅片材料,在综合考虑强化换热和减小轴向导热影响两方面因素下,并非高导热系数材料的传热性能最佳,而是在不同Re下,最大换热因子均对应一个最佳的导热系数。To reduce the influence of axial heat conduction （AHC） on the thermal performance of plate-fin heat exchanger （PFHE）, the models with/without consideration of axial heat conduction are analyzed by CFD technique. A dimensionless parameter η is introduced to confirm the influence of AHC on PFHE. The factors influencing dimensionless parameter η, such as type of fin, working condition, structure of fins, cryogenic fluid and material, are evaluated. The results show that the thermal performance of the PFHE is greatly affected by AHC. Type of fin, working condition, structure of fins, kind of fluid and material are the key factors affecting η. Specifically, AHC aggravates the thermal performance of PFHE when the Reynolds number is less than 600, in this case the effect of AHC should be considered for selection of fins. The η of plain fins is higher than that of offset strip fins. Calculating three groups of plain fins, it is also revealed quantitatively that for plain fins the dimensionless parameter r2 gets the maximum when the dimensionless parameter β is 70 and the fin density γ is 4. 1. η increases with Prandlt numberfor different cryogenic fluids. Considering enhancing heat transfer and reducing the effect of axial heat conduction, every optimum thermal conductivity corresponds with a best conducting coefficient at different Reynolds number.

关 键 词：轴向导热 板翅式换热器 数值模拟 

分 类 号：V511[航空宇航科学与技术—航空宇航推进理论与工程]