Enhancing laminar forced convection heat transfer by using Al2O3/PCM nanofluids in a concentric double-tube duct

In this study, a tube with a smaller diameter was inserted in an isoflux heated circular tube to form a concentric double-tube duct. The forced convection heat transfer enhancement efficacy of using concurrent flows of Al2O3/PCM nanofluids through outer annulus/inner tube of this resulting double-tube duct to replace its parent single-tube (with water) was experimentally investigated. The results showed that a high total flow rate combined with a high concurrent flow ratio could effectively increase heat transfer effectiveness. When heating power = 200 W, Reynolds number = 1700, and the concurrent flow ratio = 2.38, for 1% Al2O3-water nanofluid in the outer annulus and 4.63% phase-change nanofluid in the inner tube, the convective heat transfer increased by 32%. Due to the excessive pressure drop, the figures of merit of the investigated objectives are all less than 1.

Automated summary

This study investigates the improvement in convective heat transfer by using concurrent flows of Al2O3/PCM nanofluids in a concentric double-tube duct. The results show that high total flow rate and concurrent flow ratio can effectively enhance the heat transfer effectiveness.