Numerical investigation of cutting edge effect on fluid flow and heat transfer for in-phase trapezoidal air channels

• Published in: Alexandria engineering journal 2018-06, Vol.57 (2), p.911-926
• Main Authors: Abd Rabbo, M.F., Badawy, M.T.S., Sakr, R.Y., Gomaa, A.G., Rashed, H.R., Fawaz, H.E.
• Format: Article
• Language: English
• ISSN: 1110-0168
• DOI: 10.1016/j.aej.2016.11.019

This work is concerned with the numerical investigations of heat transfer and friction factor penalty inside trapezoidal in-phase corrugated-plate air channels. The influence of the flow rate represented by Reynolds number (100–1000), corrugation aspect ratio (0.2–0.5) and cutting edge ratio (0–0.6) on the flow characteristics and heat transfer was investigated. By cutting the sharp edged corners for trapezoidal channel, the large lateral vortex of the triangular channel was gradually damped resulting in lower recirculation area, lower recirculation velocities and lower velocity gradients damping the high peaks of the shear stress observed in the triangular case resulting in lower isothermal friction factor. However, the mixing effect produced by the lateral vortex decreased with its damping, which led to less uniform temperature profile resulting in lower sharper wall temperature gradients with thicker boundary layer thickness, so lower values of the Nusselt number were obtained. New correlations were developed based on the present results to evaluate Nusselt number and friction factor as a function of Reynolds number, corrugation aspect ratio, relative spacing ratio and cutting edge ratio for different corrugation shapes. The predicted results are consistent with the numerical and experimental data and lie within ±10% deviation. Keywords: Forced convection, Trapezoidal duct, Corrugated channel, Heat exchanger