17.30 Consider the composite solid shown. Solid A is a ther- mally conductive material that is 0.5-cm thick and has a thermal conductivity, ks = 50 W/m. K. The back side of solid A (x = 0) is thermally insulated. Electrical current is applied to solid A such that 20 W per cm is generated as heat. Solid B is 0.2-cm thick and has a thermal conductivity of kg = 20 W/mK. The surface of solid B is exposed to air. The surface temperature, T., of solid B is 80 C. The bulk air temperature is constant at 30 C. The process is at steady state a. What is the heat-transfer rate per unit area (flux) at x = LZ? What is the temperature T, at x = L, the boundary between solid A and solid B? b. What is the required convective heat-transfer coefficient, h, for the flowing air? c. What is the temperature To at x = 0, the insulating side of solid A