摘要
三叶孔板是以纵向流形式强化管壳式换热器性能的一种典型支撑板结构,具有附加阻力小和能够降低管束流激振动等诸多优势。为了分析三叶孔板对管壳式换热器壳程传热性能的强化效果和机理,本文依据周期性和对称性特征构建了不同孔高的换热器单元流道模型,采用重整化群k-ε湍流模型和SIMPLE耦合算法分析其壳程流场分布特征并评估其综合换热性能。结果表明,三叶孔板换热器Nu数和阻力系数较无孔板管壳式换热器均有所增加,相对Nu数(Nu/Nu_0)和相对阻力系数(f/f_0)随孔高H增大而减小,性能评价指标(performance evaluation indicators,PEC)随孔高H增大而增大。与无孔板管壳式换热器相比,三叶孔板换热器壳程纵向各处场协同角β较小而纵向涡强度?_x较大,因此场协同性的改善和纵向涡强度的提高是三叶孔板强化换热的原因。
Trifoil-hole baffle is a typical support plate which can improve heat transfer performance of tube and shell heat exchanger in the form of longitudinal flow,with many advantages such as smaller resistance and the ability of flow induced vibration weakening. In order to analyze the heat transfer enhancement effect and mechanism of trifoil-hole baffle on the shell side of tube and shell heat exchanger,a series of unit channel models for trifoil-hole baffle with different hole height H was built according to the periodical and symmetrical characteristics. The renormalization group k-epsilon turbulence model and SIMPLE coupling algorithm were adopted for numerical simulation of shell side flow and comprehensive heat transfer performance evaluation. Results showed that Nusselt number Nu and resistance coefficient f of heat exchanger with trifoil-hole baffle are all larger than that without trifoil-hole baffle. Both the relative ratio of Nu/Nu0 and f/f0 decrease with H but the value of performance evaluation indicators（PEC）increases with H. Besides,the surface average of synergy angle β is lesser and longitudinal vortex magnitude ？x is larger for heat exchanger with trifoil-hole baffle compared with that without trifoil-hole baffle,which illustrate the improvement of field synergy and intensification of longitudinal vortex all contribute to the heat transfer enhancement of trifoil-hole baffle.
出处
《化工进展》
EI
CAS
CSCD
北大核心
2017年第2期465-472,共8页
Chemical Industry and Engineering Progress
基金
国家自然科学基金(51406138)
湖北省自然科学基金(2015CFB521)项目
关键词
三叶孔板
强化换热
综合性能
机理分析
trifoil-hole baffle
heat transfer enhancement
comprehensive performance
mechanism analysis
