As a new research and technology frontier, nanofluids are used to enhance heat transfer including single-phase heat transfer, nucleate boiling heat transfer, flow boiling heat transfer and critical heat flux. This paper presents an overall review of a number of patents on nanofluid heat transfer technologies and their applications for the energy efficiency improvement in various thermal systems in recent years. Although a number of patents on nanofluids heat transfer technologies (more than 20 patents) have been invented, the fundament mechanisms of nanofluid heat transfer have not yet well understood so far. Thus, the applications of these technologies are greatly limited. According to this review, the future developments of these technologies are discussed. In order to be able to put the nanofluid heat transfer technologies into practice, fundamental studies are greatly needed to understand the physical mechanisms.
Keywords: Nanofluids, nano-particles, thermal conductivity, single phase heat transfer, nucleate boiling, flow boiling, evaporation, critical heat flux (CHF), heat transfer enhancement, cooling