Experimental validation of numerical model for evaluation of local heat transfer coefficient in coiled tubes

The efficiency of the enhanced heat transfer equipment was widely investigated in literature by adopting both experimental and numerical approaches. Obviously, the numerical tools allow improving the knowledge of the fundamental heat transfer mechanisms in curved geometries, since they enable to evaluate punctually the velocity and temperature distributions. On the other hand, it has to be pointed out that the numerical results can be considered reliable only if they are validated throughout the comparison with either analytical results or experimental data. The validation of numerical models is usually carried out by considering average heat transfer performances, therefore this approach does not guarantee that these models enable to evaluate the local heat transfer phenomena with the same accuracy. In the present paper a promising numerical tool for evaluating local convective heat transfer in coiled-tubes, within the laminar regime, is presented. The Navier-Stokes and energy equations are solved by means of the open-source CFD software OpenFOAM®, with second-order accurate finite-volume schemes, within the framework of the SIMPLE algorithm. The robustness of the numerical model is assessed by comparing the numerical outcomes to the local experimental data available in literature.