Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.
This study presents a comprehensive numerical analysis of the convective heat transfer on the external side of a compact fintube heat exchanger. The aim is to study the influence of key geometric parameters on both fluid flow and heat transfer processes in order to design more compact devices. The parameters are: fin spacing, tube diameter and tube alignment; i.e., inline or staggered, for a set of typical operating conditions. The parametric analysis is established on a six-tube baseline heat exchanger model, where air flows over the tubes and water flows at high speed inside the tubes. The mathematical model of the convection process is comprised of the continuity, momentum and energy equations, in Cartesian coordinates, which is solved under specific flow and temperature values using the finite element method. From computed velocity, pressure and temperature fields, the values of heat rate and pressure drop are then calculated for a range of flow rates in the laminar regime. Results from this investigation indicate that tube diameter and fin spacing play a role in the amount of heat being exchanged and that, for a given device, the length needed to exchange 90% of the energy that could be achieved by the baseline model, is confined to less than 1/2 its actual size, and to exchange 98% of the associated thermal energy, less than 2/3 of its size is necessary.
