Question

In a manufacturing process, a transparent film is being bonded to a substrate as shown in the sketch, where Lj = 0.8 mm, with an associated k, =0.025 W/m-K and Ly =1.0 mm with an associated ks =0.05 W/m-K. To cure the bond at a temperature To, a radiant source is used to provide a heat flux d" (W/m2), all of which is absorbed at the bonded surface. The back of the substrate is maintained at T while the free surface of the film is exposed to air at T, and a convection heat transfer coefficient h. Air Th 90" L Film Bond, T, L Substrate Ti (a) Assume the following conditions: T =20°C, h =50 W/m2.K, and T1 =30°C. Calculate the heat flux d", in W/m2, that is required to maintain the bonded surface at To =60°C. (b) For the same conditions as part (a), except the film is not transparent and all of the radiant heat flux is absorbed at its upper surface, determine the heat flux, in W/m2, required to achieve bonding.

Answer 1

Y qui From E ciscuit for the given situation. Start by making the thermal 92" energy balance, Too 90" = 9, +92" (To-Tos) Ls/ks (LA + KF h Ri=Yh T1 Ts R2=44 To 1 KE R3 = Ls ks To-TI) + .90" 60-30 + 60-20 (0.0005) 0.0008 + 0.025 Given data Too = 200 h = 50 W/m²K Ti = 30°c To 60°C If=0.8 mm Kf 0.025 w/onk Imm ks 0.05 w/mk q 2269.23 W/m² Ls. This is the heat required to keep the bond surface at 60°C. © Film is not transparent and all of radiant heat flere is absorbed at upper surface. Find the surface temperature Heat flum To-Ts Ti-To 90" = Ts-Too + Ts-Ti (Lf/kr) /h Le + Les is 60-TS 108- 30-To (150) (0.0008 0.0008 0.025 5900 W/m2 Ausb ts=108°c Islks - 20 + 108-30 0.001) + 0-05 O-025 0.001 0.05 90"

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