内螺旋外棘齿管对流换热与流阻实验研究

针对火力发电厂无铜化运行需求．研制并加工出一种钢质双侧强化传热管一内螺旋外棘齿管。采用通用的强化传热管试验装置，对5根不同结构参数的内螺旋外棘齿管进行了水平单管管外蒸汽冷凝和流阻特性试验研究。根据大量实验数据，拟合出实验雷诺数尺P范围内的管内换热努塞尔数Nu及阻力系数f的计算关联式，并对内螺旋外棘齿管的热力性能进行了评价。实验研究发现：所有内螺旋外棘齿管管内换热系数比光滑管提高了42％～152％，同时阻力系数增加了48％～350%。最后得出结论：无论在何种工况下运行。内螺旋外棘齿管的换热与流阻综合性能均优于光滑管。可用做发电厂换热设备的管芯。大大提高电厂热能的利用。

Experimental investigation on convective heat transfer and flowing friction in RISG tubes

Aiming at the need of non-copper in boiler feedwater system in power plants, a new type of steel two-side heat transfer enhancement tube, namely ratchet tube with internal spiral grooves (RISG tube), was designed and manufactured. By use of a general steam condensation testing equipment only for horizontal single tube, a set of experimental tests are conducted on 5 RISG tubes with different structural parameters to investigate the characteristics of heat transfer and flowing friction. Based on a lot of experimental data, the correlations of internal heat transfer coefficient and friction factor are obtained in the range of experimental Reynolds number. Furthermore, performance evaluation criteria are used to obtain quantitative estimates of the benefits offered by RISG tubes with water flowing in them. As the experimental results indicated, compared with smooth tubes, the internal heat transfer coefficient of all RISG tubes is improved by 42% to 152%, and the flow resistance coefficient increased by 48% to 350%. The integrate capability of RISG tubes in heat transfer and flowing friction is better than that of smooth tubes under any condition. As a result, RISG tubes can be used in heat exchanging equipments of power plants to considerably enhance the utilization of thermal energy.