DOI: 10.1615/ICHMT.2008.CHT
ISBN Print: 978-1-56700-253-9
ISSN: 2578-5486
DNS OF FLOW AND HEAT TRANSFER IN FIN-TUBE HEAT EXCHANGERS
RÉSUMÉ
The periodic array of parallel fins in normal to the circular tube of a fin-tube heat exchanger is modelled with a unit cell that consists of two narrowly-gapped parallel thin-plates embedding a heated circular cylinder in normal, and by enforcing a periodic boundary condition at the mid-plane of the solid plates. The three-dimensional Navier-Stokes and energy equations for convective heat transfer in fluids and the energy equation for heat conduction in solids of the unit-cell domain are solved numerically with a DNS method. Conjugated boundary conditions were imposed at the solid-fluid interface. The three dimensional flow and temperature fields were obtained by simulating a fin-tube heat exchanger used in commercial air conditioners. The numerical results show that the heat is transferred dominantly by conduction through the solid fins. In the practical velocity range, the heat fluxes through the fins are approximately linearly proportional to the fin thickness. The drag force and the effective fin size for optimal fin design for heat transfer as shown by the present numerical results are in good agreement with the commercial design.