Airside performance of sinusoidal wavy fin-and-tube heat exchangers subject to large-diameter tubes with round or oval configuration

A comparative study regarding airside performance of sinusoidal wavy fin-and-tube heat exchangers (FTHXs) having round and oval tube configurations is experimentally investigated and numerically verified. The computational fluid dynamics (CFD) method is also adopted to analyze detailed local heat transfer performance. The diameter of round tube is 16.3 mm while the oval tube contains diameters of 21.0 mm (major) and 10.6 mm (minor) subject to tube rows of 2-6. Results show that the FTHXs having round configuration performs higher pressure drop when the fin pitch (F-p) is 3.0 mm, however, the oval configuration conversely shows higher pressure drop with the F-p of 1.8 mm. Meanwhile, the effect of F-p on the heat transfer performance is rather small for round configuration with the tube row of 2 and 4. When the tube row increasing to 6, the heat transfer coefficient can be improved by about 10-20% and 9.3-25.2% for FTHXs with round and oval configurations, respectively, by increasing the fin pitch from 1.8 mm to 3.0 mm. The existing experimental correlations for wavy FTHX having round configuration fail to predict the present experimental data due to different ranges of fin pitch, tube pitch and tube diameter. The overall performance of twelve tested samples are also compared using JF ratio factor.