滴形管换热性能的实验研究
Experimental Study on Heat Transfer Performance of Drop Tube

采用特殊形状和表面的管子是最为常用、有效的强化换热手段。本文基于滴形管换热器回收天然气锅炉排烟余热，提出了烟气侧的换热系数实验关联式。通过改变换热管间的排列间距，在不同烟气流量下，对圆管和滴形管的换热性能及影响因素进行了分析。通过与实验数据的比较，证明实验关联式可正确反映凝结换热的特性。实验结果表明：不同烟气量通过滴形换热管的压损小于圆管，约为圆管的0.33~0.38倍；烟气温度降大于圆管；冷却水通过滴形管的温升高于圆管；换热系数滴形管比圆管的提高约7%，表明滴形管的换热性能优于圆管。可见对于有凝结换热过程发生时，滴形换热管具有强化换热的作用。
The tubes with special shape and surface are the most commonly used and effective methods to enhance the heat transfer. In this paper, the heat transfer coefficient correlation of gas side was experimentally put forward according to liquid drop tube heat exchanger for recovering waste heat of natural gas boiler. In different flue gas flow rate, the heat transfer performance and influencing factors of the round tube and drop tube were analyzed by changing the arrangement distance between the heat exchange tubes. Compared with the experimental data, it was proved that the experimental correlation can correctly reflect the characteristics of condensation heat transfer. The results showed that the pressure loss of the different flue gas through the liquid drop tube heat exchanger was smaller than that of the round tube, which is about 0.33~0.38 times of the round tube; the flue gas temperature drop was larger than that of the round tube; the temperature rise of the cooling water through the liquid drop tube heat exchanger was higher than that of the round tube; the convection heat transfer coefficient of the liquid drop tube heat exchanger was increased by about 7% than that of the round tube, indicating that the heat transfer performance of the liquid drop tube heat exchanger was better than the round. For the condensation heat transfer process, the liquid drop tube heat exchanger has the effect of heat transfer enhancement