Heat Transfer Enhancement in a Plate Heat Exchanger With Rib-Roughened Surfaces

摘要

Experimental and numerical investigations of the forced convection heat transfer in flat channels with rectangular cross section are presented in this paper. The heat transfer is enhanced by rib-roughened surfaces applied to the wider walls of the duct. The flow rates have been varied between the Reynolds numbers 500 and 10.000, covering hte range from laminar to low turbulent flow. Various configurations (rib: shape, size, spacing, angle of attack, arrangement, duct: width, height, wall temperature) have been investigate.d The local heat transfer coefficients have been obtaiend by holographic interferometry. Local hydrodynamic parameters (with special interest to turbulent kinetic energy and Reynolds shear stresses) were measured by a laser Doppler velocimeter (LDV). According to the configurations examined experimentally, numerical CFD-calculations also have been performed. To increase the accuracy of the numerical calculations for problems with simultaneous laminar and turbulent flow regimes, and empirical procedure is proposed.