搭接方式对螺旋折流板换热器壳程性能的影响

Effects of baffle connection manner on shell-side performance of heat exchanger with helical baffles

对螺旋折流板换热器进行了数值模拟,研究了相同螺距下搭接方式对壳程流动与传热性能的影响。结果表明,壳程传热系数与压降均随搭接量的增大而减小,且后者降低的幅度大于前者;连续搭接时三角区漏流增大了中心区域横向和纵向冲刷管束的速度,但整体分布不均匀,折流板背风侧流动较差;随搭接量的增大,边缘三角区增强了靠近壳体壁面区域的流动,改善了壳程的流场状况;折流板交错搭接时中心区域换热管热通量较连续搭接大幅降低,传热沿径向分布的不均匀性大大减轻。

A 3D numerical investigation for heat exchanger with helical baffles was carried out to study the effects of baffle connection manner on shell-side flow and heat transfer characteristics under the same helical pitch. The results show that both the shell-side heat transfer coefficient and pressure drop decrease with the increase of the overlap size at certain mass flow rate. The latter decreases more quickly than the former. When the baffles are arranged in a continuous manner, the leakage from the triangle zone increases the velocities of fluid flowing across the tube bundle perpendicularly and along the tubes in the central zone, but the overall velocity distribution is non-uniform and the flow on the leeward side is poor. As the overlap size increases, the leakage from the marginal triangle zone increases the velocity in the region near the shell so that the flow field is improved. The heat flux on the central tubes is much lower and the heat transfer is more uniform along the radial direction when the adjacent baffles are connected in an overlapped manner compared with the case when the adjacent baffles are arranged in a continuous manner.