This project investigated new methods to improve the thermal performance of heat exchangers by combining overlapped twisted tape inserts with nanofluids, using advanced computational simulations. The aim was to enhance heat transfer efficiency in a double-pipe heat exchanger while keeping energy consumption and mechanical complexity low. The study used a two-phase aluminium oxide (Al₂O₃)–water nanofluid circulating through a double-pipe system fitted with twisted tape inserts in both the inner and outer tubes. Two main configurations were examined: one with co-swirling tapes, where both tapes rotate in the same direction, and another with counter-swirling tapes, where they rotate in opposite directions. These designs generate strong secondary flow structures that disrupt the thermal boundary layer and promote better mixing of the working fluid, leading to improved heat transfer.
The counter-swirling configuration demonstrated the highest performance, increasing the average heat transfer rate, expressed as the Nusselt number, by up to 68.7 per cent compared with a smooth tube, while maintaining a reasonable pressure drop. At a Reynolds number of 1000 and a 3 per cent nanoparticle concentration, the system achieved a performance evaluation criterion (PEC) of 1.40, indicating a well-balanced improvement in thermal and hydraulic performance. These outcomes have particular relevance to the nuclear sector, where efficient and reliable heat exchange is essential for reactor cooling, waste heat recovery, and safety assurance. The approach offers potential for developing compact, high-performance, and passive cooling systems suitable for small modular reactors (SMRs), fusion reactor designs, and other advanced nuclear technologies.
Beyond nuclear applications, this research provides valuable insights for industrial heat recovery, renewable energy, and advanced thermal management systems aimed at improving energy efficiency and sustainability.