Problem 1 (33 points): The walls of a refrigerator are typically constructed by sandwiching a layer of insulation between steel metal panels. Consider a wall made from fiberglass insulation of thermal conductivity ki = 0.046 W/mK and thickness Li = 50 mm and steel panels, each of thermal conductivity kp = 60 W/mK and thickness Lp = 3 mm. If the wall separates refrigerated air at Ti = 4-deg C and ambient air To = 25-dge C, what is the heat gain in the refrigerator per unit surface area? The coefficients of natural convection at the inner and out surfaces may be approximated as h₁ = ho = 5 W/m²K.