关于管内单相对流换热强化的极限问题

从场协同理论出发,分析了通道内表面全部为射流冲击换热表面时的极限换热率;将全射流冲击管内换热与普通流动管内换热进行了比较。给出了层流和紊流工况下全射流冲击换热可能达到的最大强化比。针对相同R e,分析得出:在层流充分发展段,全射流冲击通道的强化极限是16.9倍;在紊流充分发展段是3.5倍。综合现有各种通道内强化换热的研究结果进行比较,其换热率均低于全射流冲击管内换热率,其中层流工况以折流翅片式通道和交叉缩放椭圆管的换热率与极限换热率最为接近;紊流工况以内插螺旋丝强化管最为接近。

Study on limit of heat transfer rate for internal single-phase convection

The limit of the heat transfer rate that corresponds to the allimpinged internal tube flow was analyzed from the view of the field synergy principle.The comparison of the allimpinged heat transfer and the conventional internal heat transfer has been conducted.The potential maximum enhancing ratio for both the laminar and the turbulent flow was discussed.The analysis reveals that the maximum enhancing ratio is 16.9 for the laminar and 3.5 for the turbulent at the same Reynolds number.Enhancing ratios of the typical configurations in the literature are found to be all lower than that of the allimpinged structure.Among the compared enhanced configurations the channel with flowinclining fins and the alternate elliptical axis tube show the proximal enhancement effect to the maximum ratio for the laminar flow and the helixinserted tube is the best for the turbulent flow.