Turbulent heat transfer of natural convection between two vertical parallel plates

We measure heat transfer coefficients of natural convection between two vertical smooth parallel plates heated uniformly in the laminar, transition, and turbulent regions. The heat transfer characteristics are experimentally investigated with changing width, δ, between the vertical parallel plates, wall heat flux, q_w, overall watercourse length, L,of the vertical parallel plate and heating conditions. For natural convection between the vertical parallel plates, in the turbulent region of , the heat transfer is strongly suppressed owing to the effect of combined convection. On the contrary, the heat transfer in the laminar region is enhanced due to the tunnel effect. These tendencies become pronounced with decreasing δ and increasing L.The location of the heat transfer reduction shifts downstream with increasing q_w under a fixed δ. Furthermore, under smaller δ, we cannot clearly distinguish the transition process in accordance with both the heat transfer enhancement in the laminar region and the heat transfer reduction in the turbulent region. © 2001 Scripta Technica, Heat Trans Asian Res, 31(1): 56–67, 2002