Consider the Nichrome wire (D = 1 mm, ρe = 10-6 Ω· m, k = 25 W/m· K, ε = 0.20) used to fabricate the air heater of Problem 3.86, but now under conditions for which the convection heat transfer coefficient must be determined.
(a) For atmospheric air at 50°C and a cross-flow velocity of 5 m/s, what are the surface and centerline temperatures of the wire when it carries a current of 25 A and the housing of the heater is also at 50°C?
(b) Explore the effect of variations in the flow velocity and electrical current on the surface and centerline temperatures of the wire.