螺旋片强化的套管式换热器壳侧传热特性  

Heat Transfer Performance of the Shell Side of Double-Pipe Heat Exchanger Enhanced with Helical Fins

作　　者：张丽[1,2] 田密密[2] 吴剑华[1,2] 

机构地区：[1]天津大学化工学院,天津300072 [2]沈阳化工大学化学工程学院,辽宁沈阳110142

出　　处：《高校化学工程学报》2011年第1期24-29,共6页Journal of Chemical Engineering of Chinese Universities

基　　金：中央支持地方高校发展专项资金项目(2050205);辽宁省高校创新团队项目(2007T143)

摘　　要：为揭示螺旋片强化套管式换热器壳侧传热的机理,以指导此类换热器的进一步强化,对螺旋片强化的套管式换热器壳侧的传热和阻力特性进行了实验研究,并与光滑内管换热器进行了比较;利用可实现的k-ε湍流模型,对螺旋片强化的套管式换热器壳侧流体的流动和传热特性进行了数值模拟,研究了正交螺旋坐标系下壳侧螺旋通道中的流场结构。实验结果表明,螺旋片能显著提高套管式换热器壳侧的传热性能;在Re为4000～14000,螺旋升角分别为45°、37°、27°、14°的换热器的传热系数是光滑内管换热器的1.3～4.2倍;螺旋升角越小的换热器传热效果越好,但压降也越大。数值模拟结果表明,螺旋片能改变壳侧流场结构,使流场中产生了二次流动,从而强化了传热;螺旋升角越大,螺旋通道中心处的二次流动越弱。因此,对于螺旋升角较大的换热器,采用螺旋片复合其它强化技术改善螺旋通道中心处的二次流动状况是进一步提高其传热性能的关键。In order to discover the heat transfer enhancement mechanisms of the shell side of double-pipe heat exchanger with helical fins and to guide the further heat enhancement of this kind of heat exchanger,heat transfer performance and flow resistance of shell side of the above mentioned heat exchanger were investigated experimentally and compared with those of the heat exchanger with smooth inner tube.The fluid flow characteristic and heat transfer performance of the shell side of double pipe heat exchanger with helical fins were investigated numerically by applying realizable k-turbulent model,and using the orthogonal helical coordinate system,the fluid flow characteristics of the shell side helical channel were analyzed.The experimental results show that the heat transfer performance of double-pipe heat exchanger shell side is enhanced significantly by helical fins,and at Re = 4000~14000,the heat transfer coefficients of the exchangers with pitch angle 45,37,27,14 respectively are 1.3~4.2 times as much as that of the exchanger with smooth inner tube.It was also found that the smaller the pitch angle,the higher the heat efficiency;however,the pressure drop increases with the decrease of pitch angle.The numerical simulation results show that the helical fins can change the fluid flow characteristics of the shell side,and the secondary flow appeared in the flow field enhances the heat transfer performance.It was also found that,with the increase of the pitch angle,the secondary flow at the center of the helical channel weakens.Therefore,as to the heat exchanger with large pitch angle,in order to improve its heat transfer performance further,the most important thing is that some other enhancement measures should be adopted to combine with the use of helical fins to strengthen the secondary flow at the center of the helical channel.

关 键 词：螺旋片 套管式换热器 强化传热 螺旋升角 二次流动 

分 类 号：TK12[动力工程及工程热物理—工程热物理] TK172[动力工程及工程热物理—热能工程]