An experimental study on mixed convection in a horizontal rectangular channel heated from a side

Experiments are performed to study the mixed convection flow and heat trans fer in a horizontal rectangular channel heated from a side. The channel is made of two vertical parallel plates with one of the plates heated uniforml y and the opposite plate well insulated The gap between the parallel plates is small and the height to gap ratio of the channel cross section is 6.67 Both flow visualization and the heat transfer along the heated wall are mea sured. The Reynolds number ranges from 317 to 2000, the buoyancy parameter, Gr/Re-2, from 0 to 20000 and Pr of the airflow is 0.7 Flow structure insid e the channel is visualized by injecting smoke at the inlet flowing along t he heated side wall. The heated buoyant flow accumulates in the upper regio n of the channel, which grows in size as the buoyancy parameter increases. The accumulated flow is thermally stable and has a slower motion which can reduce the heat transfer enhancement by the buoyancy force. The effect of t he Reynolds number and the buoyancy parameter on the heat transfer is prese nted and discussed. Comparisons of the Nusselt numbers with the case of the vertical channel flow and the prediction similar to the case of a horizont al flow through a heated vertical plate are also made. The normalized Nusse lt numbers are found in proportion to the buoyancy parameter correlations o f the heat transfer data in terms of this parameter have been very successf ul.