Nanofluids as heat transfer fluids: Hurdles to industrial application and economic considerations

Nanofluids have gained substantial interest over the past years due to their enhanced thermal properties. However, these nanoparticle dispersions remain scarcely used in industrial applications. In this work, we demonstrate how the stability of nanofluids and economic factors are the major hurdles preventing their industrial large-scale use through an economic analysis. The cost-effectiveness of multiwalled carbon nanotubes (MWCNT)-water and copper oxide-water nanofluids used in a concentric tube heat exchanger as substitutes for freshwater was assessed in four different scenarios. It was determined that three of the four cases were not economically viable, as a deficit was generated due to a recurring annual investment for the renewal of the nanofluids because they destabilized with time. The fourth case, however, was sustainable because of the nanofluid's high stability (5 years) and showed a payback period on investment of less than a year. Finally, a tool illustrating the operating window for nanofluid economics in our selected heat exchanger geometry was developed.