弓形折流板换热器流动与传热性能的数值模拟

Numerical Simulation of Flow and Heat Transfer Performance of Segmental Baffle Heat Exchanger

为了探究折流板结构对换热器整体性能的影响,课题组通过FLUENT模拟分析弓形折流板板间距以及缺口高度占比这2个关键变量,得到不同条件下换热器流场和温度场的分布情况,并以换热系数h、压降ΔP以及综合性能参数η作为换热评价指标,研究了不同结构参数对换热性能的影响,并分析了2个关键变量之间的关联性。结果表明:随着板间距的减小,流动与传热“死区”区域变小,换热系数及壳程压降增大,板间距较小的换热器在低入口速度工况下综合性能相对较好;当板间距为185 mm时,换热系数和压降随板缺口高度占比的增大而减小,此时选择缺口高度占比为0.30可获得较佳综合性能;另外,通过研究2个变量间的关系发现板间距较小时应选择相对较大的缺口高度占比以保证其较优性能。

In order to study the influence of the segmental baffle structure on the overall performance of shell and tube heat exchangers,FLUENT software was used to simulate and analyze the influence of two key variables of distance between segmental baffles and notch height ratio,and distribution of flow field and temperature field under different conditions was obtained.Taking the heat transfer coefficient h,pressure dropΔP and comprehensive performance parameterηas heat transfer evaluation index,the influence of different structural parameters on heat transfer performance was studied,and the correlation between the two key variables was analyzed.The results show that the dead zone of flow and heat transfer becomes smaller and the heat transfer coefficient and shell side pressure drop increase with the decrease of distance between segmental baffles.The comprehensive performance of the heat exchangers with smaller distance between baffles is relatively better under the condition of low inlet velocity.The heat transfer coefficient and pressure drop decrease with the increase of the notch height ratio when the distance between segmental baffles is 185 mm,so the better comprehensive performance can be obtained by choosing the notch height ratio of 0.30.In addition,by studying the relationship between the two variables,it is found that when the distance between baffles is small,a relatively larger notch height ratio should be selected to ensure its better performance.