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.