Performance assessment of aluminum slitted finned tube heat exchangers with small tube diameters

Abstract

This paper investigates the effects of different geometric parameters for the fin structure of an aluminum slitted finned tube heat exchanger on the heat transfer and resistance characteristics on the air side of the heat exchanger. Aluminum offers good ductility, electrical conductivity, and thermal conductivity at low economic cost, and the slitted fin structure is effective in improving the overall heat transfer performance of the heat exchanger. This study presents a numerical investigation of the effects of important structural parameters (including the base tube outer diameter $d_o$, the fin thickness ${\delta }_f$, the slit height $S_h$, the slit width $S_w$, and the slit length $S_L$) in the aluminum slitted finned tube heat exchanger’s fin structure on its air-side heat transfer and flow resistance characteristics. Recommended parameter combinations were identified and the experimental data were fitted to derive a simplified mathematical model to represent the complex dataset. The results show that $S_h$ has the most significant effect on the overall heat transfer performance of the slitted finned tube heat exchanger, while the effects of $S_L$ and $S_w$ are less obvious and are basically negligible. The favorable parameters combinations were obtained after improvement as follows: $d_o$=5.6 mm, ${\delta }_f$=0.115 mm, $S_h$=0.6 mm, $S_w$=1.1 mm, $S_{L1}$=9.0 mm, and $S_{L2}$=6.6 mm. The results of this study will be highly significant in guiding improvement of the structure and the performance of aluminum slitted finned tube heat exchangers with small tube diameters.