螺旋隔板三维翅片管传热实验研究与数值模拟

Heat transfer experimental research and numerical simulation on three-dimensional finned tube with helical baffles

文章对冷却水在换热器管程流动并与壳程的热油逆流换热条件下,对螺旋隔板三维翅片管换热器的传热与压降性能进行了实验研究,并与光滑管进行了对比。在相同壳程Reynolds数下,三维翅片管的壳程Nusselt数是光滑管的2.2—2.9倍,而压降是光滑管的2.3倍左右。采用计算流体力学软件F luent 6.0对螺旋隔板三维翅片管和光滑管换热器进行了数值模拟。结果表明,螺旋流条件下光滑管表面速度矢量均匀、稳定,而三维翅片表面的速度矢量因翅片激发流体而产生湍动和不规则的二次流,从而强化了流体的对流传热。对于螺旋隔板三维翅片管换热器,壳程Nusselt数和压降的数值模拟结果与实验计算值吻合良好,最大偏差分别为6.3%和9.8%。

In counter flow mode operation the heat transfer and pressure drop performance of a helical baffle heat exchanger with three-dimensional finned tube were experimentally investigated with hot oil in the shell side and cold water in the tube side. One plain tube was chosen for comparison. When Reynolds number is the same, Nusselt number and pressure drop in the shell side of a helically baffled heat exchanger combined with three-dimensional finned tube are 2.2-2.9 times and 2.3 times those of a helically baffled heat exchanger with plain tube, respectively. Fluent 6.0, a commercial software for computational fluid dynamics, was used in the simulation of the flow and heat transfer performances in the experimental heat exchangers. The results show that the velocity vector of helically baffled heat exchanger with plain tube is uniform and stable, but the velocity vector of helically baffled heat exchanger with finned tube is very irregular due to the eddies and secondary flow generated by fins on the surface of three-dimensional finned tube. The present numerical results are in good agreement with the experimental data, the maximum difference is approximately 6.3% for Nusseh number and 9.8% for pressure drop, respectively.