Effect of a micro-grooved fin surface design on the air-side thermal-hydraulic performance of a plain fin-and-tube heat exchanger

In this study, the effectiveness of plain fin-and-tube heat exchangers constructed using anisotropic, micro-patterned aluminum fins has been explored. These fins which can more completely drain the condensate that forms on the heat transfer surface during normal operation were selected with the aim of improving the thermal-hydraulic performance of the heat exchanger. This study presents and critically evaluates the efficacy of four full-scale heat exchangers by measuring and comparing dry/wet air-side pressure drop and dry/wet air-side heat transfer data. The prototype fin surfaces were shown to reduce the wet air-side pressure drop from 9.3% to 53%, while at the same time having a negligible effect on the sensible heat transfer coefficient under both dry and wet conditions. That is to say, this novel fin surface design has shown the ability, through improved condensate management, to enhance the performance of the heat exchanger. Data pertaining to the durability of the alkyl silane coating used in this work are also presented.

► Micro-grooved surfaces can more effectively manage condensate drainage and removal.
► Negligible effect on the sensible heat transfer coefficient under dry and wet conditions.
► Decreased the air-side pressure drop during wet operation from 9 to 53%.
►  Micro-channels may be useful for delaying the onset of condensate carryover.
► Other surface coatings and/or deposition methods should be explored for improved durability.