Investigation of the condensation heat-transfer between the wet air and 3-D finned-tube heat exchanger surface with different anti-corrosion coatings

ABSTRACT

It is a coupling solution for optimizing the materials with good thermal conductivity and anti-corrosive modified coating of flue-gas condensation heat exchangers. The paper experimentally studied the condensation heat transfer between the wet air and 3-D finned-tube heat exchanger surface in three different ways, i.e. non-coating, Ni-Cu-P organic pure-coating, and Ni-Cu-P chemical organic composite coating. Impacts of mass flow rate, moisture content, temperature of exhaust flue gas, and cooling water on the condensation heat transfer performance were investigated. The results showed that the heat transfer coefficient of the heat exchanger surface with a pure-coating layer achieves 3.1–7.4% higher compared to that with the composite coating. The pure-coating surface is inferior to the non-coating surface. The heat transfer coefficient of the copper-based heat exchanger achieves 30.1–47% higher compared to the steel-based surface. The condensate pH of modified surfaces heat exchangers is ranged from 3.08–7.17. Furthermore, the nondimensional correlations governing the flue-gas convection condensation heat transfer for different coating surfaces were established and validated with the experimental data. The validation indicates that the theoretical results are in good agreement with the experimental data.

KEYWORDS:

• 3-D finned tube
• condensation heat transfer
• anti-corrosion coating
• dimensionless correlation

Acknowledgments

We also thank the editors and the anonymous reviewers for their valuable comments and suggestions on our manuscript.

Highlights

• Near-spherical condensate is mainly distributed in the gap and on the top of the fins.

• Copper-based surface has more excellent heat-transfer performance than the steel-based ones.

• The heat-transfer performance of finned tubes is weakened through the surface modification.

• The condensate retention increases the conductive thermal resistance of 3-D finned tubes.

Additional information

Funding

This work was financially supported by Beijing Scholars Program (2015No.022), and Key R&D Project of Ningxia Hui Autonomous Region (2019BFG02016);Key R&D Project of Ningxia Hui Autonomous Region [2019BFG02016];