Maximum heat transfer rate density from ducts with wrinkled entrances

Abstract

Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.This paper reports an increase in the heat transfer rate density by using wrinkled entrance regions in ducts with laminar flow. The heat transfer rate density is increased by taking advantage of the presence of relatively isothermal fluid in the entrance regions. In order to stimulate a more complete thermal interaction between walls and fluid, the square entrances are wrinkled on the perimeter, at the one-third and the two-third positions. The new structure has two degrees of freedom. The fluid flow through the ducts is forced by the imposed pressure difference across the duct. Numerical simulations document the effects of the dimensionless pressure drop on the optimized configurations and show a fifteen percent enhancement in heat transfer rate density.