Consider a refrigerator whose outer dimensions are 1.80 m x 0.8 m x 0.7 m. The walls of the refrigerator are constructed of 3-cm-thick urethane insulation (k = 0.026 W/m·K and a = 0.36 x 1026 m2 /s) sandwiched between two layers of sheet metal with negligible thickness. The refrigerated space is maintained at 3°C and the average heat transfer coefficients at the inner and outer surfaces of the wall are 6 W/m2·K and 9 W/m2·K, respectively. Heat transfer through the bottom surface of the refrigerator is negligible. The kitchen temperature remains constant at about 25°C. Initially, the refrigerator contains 15 kg of food items at an average specific heat of 3.6 kJ/kg·K. Now a malfunction occurs and the refrigerator stops running for 6 h as a result. Assuming the temperature of the contents of the refrigerator, including the air inside, rises uniformly during this period, predict the temperature inside the refrigerator after 6 h when the repair-man arrives. Use the explicit finite difference method with a time step of ∆t = 1 min and a mesh size of ∆x = 1 cm and disregard corner effects (i.e., assume one-dimensional heat transfer in the walls)