气相旋转螺旋槽管式换热器结构优化与性能试验

Structural Optimization and Performance Test of Gas-phase Rotating Spiral Grooved Tube Heat Exchanger

粮食干燥生产中换热损失大,存在烟气热量无法高效传递,导致换热效率低等问题。本文以集管壳与列管式换热于一体的气相旋转螺旋槽管式换热器为研究对象,基于场协同与热力学理论优化螺旋槽管关键部件,探究螺旋槽管参数对换热性能的影响。以螺距、槽深及内外径比为试验因素,以努塞尔数和阻力系数为评价指标,进行三因素五水平二次正交旋转组合试验,采用多目标优化方法确定最优参数组合,当螺距为24.845 mm、槽深为1.753 mm、内外径比为0.897时,Nu为164.637,f为0.348。对优化结果进行验证试验,试验结果与优化结果基本一致。螺旋槽管平均场协同角β相较于圆管降低约2°,揭示了置于壳程内的螺旋槽管管束进口、出口及中间截面内场协同角的分布特征,整体范围内的场协同效果有所增加,结论符合场协同原理。利用强化换热综合性能指数(Performance evaluation criteria,PEC)进行评价,结果表明气相旋转螺旋槽管式换热器PEC在1.031~1.267之间,验证了螺旋槽管在换热器应用的合理性。

During the grain drying production,the heat transfer loss was great,and flue gas heat can not be efficiently transferred,resulting in low heat transfer efficiency and other problems.The gas-phase rotary heat exchanger integrating shell-and-shell and shell-and-tube heat exchanger was taken as the research object,and the key components of the spiral grooved tube were optimized based on the field synergy and thermodynamic theory.The influence of spiral grooved tube parameters on heat transfer performance was investigated.Pitch,groove depth and inner/outer diameter ratio were taken as test factors,and nussle number and resistance coefficient were used as evaluation indexes.Three-factor five-level quadratic orthogonal rotary combination experiments were carried out.Multi-objective optimization method was used to determine the optimal parameter combination,and nussle number was 164.637 and resistance coefficient was 0.348 when the pitch was 24.845 mm,the groove depth was 1.753 mm,and the inner/outer diameter ratio was 0.897.Verification experiments were carried out on the optimization results,and the experimental results were basically consistent with the optimization results.The average field synergy angle of the spiral grooved tube was decreased by about 2°compared with that of the circular tube,revealing the distribution characteristics of the field synergy angle in the inlet,outlet and intermediate sections of the spiral grooved tube bundle placed in the shell range,and the field synergy effect was increased in the overall range,which was concluded to be in line with the field synergy principle.The enhanced heat transfer comprehensive performance index was utilized for evaluation,and the results showed that the thermal performance factor of spiral grooved tube heat exchanger was between 1.031 and 1.267,which verified the rationality of spiral grooved tube in heat exchanger application.