Influence of nanofluids and rotation on helically coiled tube heat exchanger performance

The effects of using various types of nanofluids and rotation on heat transfer and fluid flow characteristics in a helically coiled tube heat exchanger (HCTHE) are numerically investigated. Mainly, the effects of nanoparticles type (Al2O3, SiO2, CuO, ZnO), its concentration (1–4%), and particle diameter (25–80 nm), base fluid type (water, ethylene glycol, engine oil), towards the heat transfer and fluid flow characteristics are comprehensively analyzed. The three-dimensional steady, laminar flow and conjugate heat transfer governing equations of a balanced HCTHE are solved using the finite volume method. The results reveal that nanofluids can enhance the thermal properties and performance of the HCTHE but it is accompanied with a slight increase in pressure drop. It is found that the Nusselt number is highest using CuO–water nanofluid in this study. In addition, rotation can be used to enhance the heat transfer rates.