Enhancing Efficiency in Double‐Pipe Heat Exchangers: A Detailed Review of NanoFluids and Their Impact on Thermal Performance

ABSTRACT This study reviews recent advances in using nanofluids to enhance double‐pipe heat exchanger (DPHE) efficiency. The review examines several types of nanofluids, that is, water‐based graphene oxide and CuO–water nanofluids, assessing their effectiveness under different operating conditions, including inlet temperature and nanoparticle volume concentration. Experimental findings demonstrate that the inclusion of nanofluids can lead to notable improvements in thermal performance factors and thermal exchange ratios, primarily due to enhanced thermal conductivity. The review shows that optimizing flow rate per unit volume and nanoparticle concentration can significantly reduce pressure drop while achieving a peak heat transfer coefficient. Furthermore, minimizing the concentration level would ensure efficient thermal performance with manageable pressure losses. Statistically, titanium dioxide nanofluids of 0.5% concentration can enhance thermal rates by 14.8%, while 115% improvement in heat transfer coefficients is ascertained using 0.6% concentration of multi‐walled carbon nanotubes. Using iron oxide nanofluids can rise heat transfer rates by 41.29%, with negligible pressure drop after exposure to a magnetic field. Furthermore, hybrid nanofluids of aluminum oxide–titanium dioxide can introduce 84% enhancement in thermal performance, emphasizing their potential to optimize heat transfer in DPHE. However, further investigation is required particularly with the use of advanced surfactants to further enhance the thermal conductivity of DPHEs, and the need for long‐term stability assessments and cost–benefit analyses to support the industrial implementation of nanofluid‐based thermal systems.