Thermal and flow analysis of different fin profiles in annular finned tube bundles

Obtaining energy from waste heat is very important in terms of energy efficiency. Recycle heat recovery units are frequently used in industry to benefit from waste heat energy. Cross-flow heat exchangers are an important part of heat recovery units. In this context, studies on cross-flow heat exchangers in terms of energy economy have attracted a lot of attention by researchers in recent years. In this study, a cross-flow heat exchanger with a annular finned tube bundle is considered. The effects of different fin geometries on heat transfer and flow frictions for the annular fin tube bundle were investigated. At this study, four different annular fin geometries, solid, perforated solid, serrated and perforated serrated, were numerically investigated. All numerical studies were carried out in three dimensions and time-independent in the Ansys-Fluent package program. In order to validate the numerical analyzes on a basis, a separate verification study was carried out for each geometry. Solid, serrated and perforated solid fin geometries were validated with similar studies in the literature. In addition experimental validation work was carried out for the perforated serrated fin geometry. For experimental validation, perforated serrated annular finned tube bundles were produced and heat transfer and pressure drop experiments were carried out in a cross-flow heat exchanger model. For numerical analysis, the appropriate turbulence model was selected depending on the validation study and the SST k-ω turbulence model was used in the analysis. Numerical analyses were carried out in the range of five different Reynolds number 5000 to 25000. Four different variable geometric parameters were determined for solid fin and six different variable geometric parameters for serrated fin. The heat transfer and flow frictions of these annular finned tube bundle geometries at different variable parameters were investigated. Dimensionless Nu number for heat transfer and dimensionless Eu number, which is friction factor, was obtained for flow friction. In addition, the heat transfer and pressure drop results of the fin geometries with the effect of variable parameters were also compared.