Numerical Analysis of Tube Heat Exchanger with Trimmed Star-Shaped Fins

Abstract

In some engineering applications, it is very desirable that the heat exchanger is as light as possible while maintaining the heat transfer rate at an acceptable level. In this context, the possibility of reducing the weight of the heat exchanger with the star-shaped fins by cutting off the thermally least efficient part of the fin was investigated. For this purpose, the rear part of the fins was trimmed to Ø28, Ø31 and Ø34 mm. Numerical analysis was used to determine the influence of each variant on the flow characteristics in the air–water heat exchanger and on heat transfer for the range of 2300 < Re < 16,000. The best results were obtained by trimming the rear part of the fin to Ø28 mm. With a 5.53% reduction in fin weight, heat transfer can be increased by up to 8.12% compared to the star-shaped fins without trimming. The pressure drop can be reduced by up to 0.92%. The trimmed fins were also compared with perforated star-shaped fins (perforation Ø2). At approximately the same weight, the trimmed fins increase the heat transfer coefficient by up to 5.75% with a reduction in pressure drop of up to 0.76% compared to the perforated fins.