Availability prediction of a double-pipe exchanger using twisted tape and nanofluid (AL2O3) technology

This experimental and theoretical study explores heat transfer enhancement in a horizontal circular tube using a nanofluid composed of Al2O3 nanoparticles suspended in distilled water (H2O), combined with a twisted ribbon insert. The twisted ribbon has a typical twist ratio of 6 (TR=6). The investigation was conducted under fully developed turbulent flow and uniform heat flux conditions, with nanofluid concentrations of 1%, 3%, and 5% by volume. The experimental setup consisted of all the necessary components for analyzing heat transfer within a double-pipe heat exchanger. The tests were conducted over a Reynolds number range of 5000–10500, with heat applied externally as hot water (at 63°C) flowed through the annular space between the tubes, while the nanofluid entered the inner tube at a temperature of 18°C. The twisted ribbon, made from wrought iron, was placed inside the inner tube. In the numerical analysis, the final results were obtained using computational fluid dynamics (CFD) to model the forced convection turbulent flow through the tube. The study found that the maximum thermal performance factor for the nanofluid was 5, achieved at a torsion ratio of 6 and a volume flow rate of 3 liters per minute. H I G H L I G H T S 1. AL2O3/H2O 0.1% nanofluid in a tube with a typical inserted twisted tape has been investigated experimentally and numerically. 2. The key fundamental dimensionless parameters, such as the Reynolds number, Nusselt number, heat exchanger (HX) effectiveness, EXERGY, and friction factor, have been analyzed. 3. The results demonstrated a significant enhancement in heat transfer and EXERGY with the inclusion of a standard inserted twisted tape.