The walls of a refrigerator are typically constructed by sandwiching a layer of insulation between sheet metal panels. Consider a wall made from fiberglass insulation of thermal conductivity ki = 0.046 W/m. K and thickness Li = 30 mm and steel panels, each of thermal conductivity kp = 50 W/ mK and thickness Lp = 4 mm. If the wall separates refrigerated air at T...; = 2 C from ambient air at 1,0 = 25 C, what is the heat gain per unit surface area? Coefficients associated with natural convection at the inner and outer surfaces may be approximated as hi = h. = 5 W/mK