Feasibility review of using copper oxide nanofluid to improve heat transfer in the double-tube heat exchanger

•A comparative analysis of CuO nanofluid and other nanofluids utilized in DTHXs under identical conditions is included.•A detailed examination of nanofluids, encompassing preparation methods, thermophysical properties, and influencing factors, is presented.•CuO nanofluid significantly improves thermal performance, leading to reduced power consumption and the possibility of reducing the heat exchanger size.•Mostly, maximum thermal enhancement occurs at high Reynolds numbers and nanoparticle concentrations. Many industrial, sanitary, and food applications use double-tube heat exchangers, prompting researchers and developers to focus on improving their thermal performance. Researchers often enhance thermal performance using either passive or active methods, or sometimes both. An approach to improving thermal performance is using nanofluids instead of conventional fluids because of their superior thermophysical properties. This article provides a comprehensive review of the double-tube heat exchanger (DTHX) using CuO nanofluid in its various configurations. Additionally, this article presents all the mathematical equations and correlations necessary for evaluating the parameters of a DTHX, both in the case of parallel and counterflow scenarios. This article also provides a comprehensive overview of nanofluids, their preparation methods, their thermophysical property calculations, and the factors that influence their performance. The review showed that CuO nanofluid is very good at improving heat transfer of the DTHX. The improvement is even better when it is used with other methods of improvement, like twisted tapes, even though the pressure drop goes up because of friction with the tube's surface. Finally, under similar conditions, CuO nanofluid clearly outperforms most oxide-based nanofluids. This improvement can reduce power consumption and reduce the DTHX size.