Heat transfer enhancement in a double-pipe helical heat exchanger using spring wire insert and nanofluid

Double-pipe helical heat exchangers (DPHHXs) are widely used for cooling and heating applications. In this study, a combination of two methods is used to enhance the performance of DPHHX. The thermal–hydraulic performance is investigated using a nanofluid of silicon dioxide and water (SiO2/water) as well as spring wire insert (SWI) experimentally and numerically. The numerical model is validated with the experimental results. The parameters such as Nusselt number, pressure drop, exergy efficiency, and thermal–hydraulic enhancement factor are investigated for Reynolds number range from 4500 to 7000. The results show the Nusselt number is enhanced with nanofluid employment and SWI. Nusselt number increases by 34