竖凹槽内螺旋波纹管的沸腾换热与PEC评价

Boiling heat transfer and PEC evaluation of helical bellows in vertical grooves

以套管结构为设计模型,通过外管流动的水对内管R32加热使其沸腾,采用CFD对不同数量竖凹槽的内螺旋波纹管进行沸腾换热模拟研究。结果表明:与光管相比,内螺旋波纹结构强化了沸腾换热但增大了内管压降,表面换热系数和内管压强分别提高至光管的147%,221%。随着竖凹槽数量的增加,竖凹槽内螺旋波纹管的表面换热系数和内管压降均先增大后减小,当竖凹槽数量为16时均达最大值,分别为光管的157%,261%。此外,通过比较不同数量竖凹槽内螺旋波纹管的强化沸腾效果与泵功率损耗的关系(PEC),发现竖凹槽数量为16时,PEC最大(1.523),因此,竖凹槽数量为16时,竖凹槽内螺旋波纹管性能最优。

In this simulation,R32 in the inner tube is heated by the water flowing from the outer tube to make it boil.CFD is used to simulate the boiling heat transfer of the inner spiral bellows with different numbers of vertical grooves.The results showed that compared with the smooth tube,the inner helix corrugated structure enhances the boiling heat transfer but increases the pressure drop of the inner tube.The surface heat transfer coefficient and the inner tube pressure increase to 147%and 221%of the smooth tube,respectively.With the increase of the number of vertical grooves,the surface heat transfer coefficient and the pressure drop of the inner tube first increase and then decrease.When the number of vertical grooves is 16,they reach the maximum value,which are 157%and 261%of the smooth tube respectively.In addition,by analyzing the relationship between enhanced boiling effect and pump loss of different number of vertical grooves,it was found that PEC obtained the maximum value(1.523)when the number of vertical grooves was 16.Therefore,the performance of spiral bellows in vertical grooves is the best when the number of vertical grooves is 16.