Consider a flat plate subjected to parallel flow (top and bottom) characterized by u∞ = 40 m/s, T∞ = 20 °C, and drag force, FD = 0.075 N. Determine the average convection heat transfer coefficient, and convective heat transfer rate associated with an L = 0.2 m long, w = 0.2 m wide flat plate when the surface temperature is Ts = 120 °C. Air (P = 1 atm, Tf = 70°C): Pr = 0.704, k = 28.0 × 10-3 W/m⋅K, cp = 1009 J/kg⋅K, ν = 1.82 × 10-5 m2/s, ρ = 1.085 kg/m3

Laminar flow normally persists on a smooth flat plate until a critical Reynolds number value is reached. However, the flow can be tripped to a turbulent state by adding roughness to the leading edge of the plate. For a particular situation, experimental results show that the local heat transfer coefficients for laminar and turbulent conditions are hlam (x) = Alamæª htur (x) - Aturæb Alam = 1.98 a = -0.5 Atur = 4.15 b = -0.3 Calculate the average heat transfer coefficients for laminar and turbulent conditions for plates of length L = 0.2 m and 2.5 m.