通过内插螺旋方法使换热器换热管内流体产生螺旋流,实验研究了管内螺旋流/螺旋流态化的颗粒直径、颗粒浓度、螺旋结构参数及温差对强化传热及除垢、防垢性能的影响.结果表明,在实验范围内,换热器换热管内螺旋流态化比螺旋流的传热系数提高15%-20%;颗粒直径5 mm比3 mm的传热系数提高5.4%;颗粒浓度15%(φ)比5%(φ)传热系数提高15.3%;外径螺旋30 mm比20 mm传热系数提高7.7%;螺距20 mm比60 mm传热系数提高11.1%.随时间连续运行,管内螺旋流态化的传热系数下降幅度远小于螺旋流,表明管内螺旋流态化具有较好的除垢防垢效果.传热温差变化对螺旋流态化强化传热及除垢、防垢性能影响较小.
Spiral insert is fixed in a heat exchanger tube for formation of spiral fluid flow. The effects of particle diameter, particle concentration, spiral structure parameters and temperature difference on the heat transfer enhancement and anti-fouling performance were examined by experiments. The results show that in the experimental ranges, comparing the values of heat transfer coefficient in different cases, the spiral fluidization is 15%?20% higher than that of the spiral flow, the particles with the diameter of 5 mm 5.4% higher than that of 3 mm particles, the high particle concentration of 15%(φ) 15.3% higher than that of 5%(φ), the spiral outer diameter of 30 mm 7.7% higher than that of 20 mm, and the helical pitch of 20 mm 11.1% higher than that of 60 mm. With continuous operation, the decline of heat transfer coefficient of the inner tube spiral fluidization is much less than that of the spiral flow, indicating good anti-fouling effect of the spiral fluidization. The heat transfer enhancement and anti-fouling of spiral fluidization are less affected by the change of temperature difference.