An experimental study of Cu-water nanofluid flow inside serpentine tubes with variable straight-section lengths

- Effect of straight section variations on performance of serpentine tubes is studied.
- Cu-water nanofluids are produced with a one-step technique at 0.1% and 0.4% wt.
- Short straight sections at beginning enhance the heat transfer and pressure drop.
- Cu-water nanofluid flow increases the heat transfer rate in serpentine tubes.