NEW CORRELATIONS FOR CONVECTIVE HEAT TRANSFER COEFFICIENTS FOR FLAT PLATE SOLAR COLLECTORS.

Experiments were performed to evaluate the convective heat transfer coefficient for a flat plate mounted in a wooden model of a roof of a building. The experiments were carried out in a closed-circuit wind tunnel and included parametric adjustments of the roof pitch and Reynolds number. The roof pitch was varied from zero to 90 degrees and Reynolds number, based on the plate length, ranged from 58000 to 250000. A transient, one lump, thermal approach was used for heat transfer calculations. Due to a separation bubble at the leading edge of the model, i. e. the roof, at the angles of attack of less than 40 degrees, the flow became turbulent after reattachment. This resulted in a higher heat transfer coefficient than previously reported in the literature. At the higher angles of attack, the flow was not separated at the leading edge and the heat transfer coefficient was found to be approximately independent of the angle of attack