reezer is maintained at -20°C and the outer wall temperature is measured to De 22°C. The floor of the freezer may be assumed to be perfectly insulated. a) Sketch the thermal resistance diagram for the freezer (10 marks) b) Calculate the total heat transfer rate that infiltrates into the freezer. (20 marks) Problem 2: (50 marks) Consider the composite wall shown below. The thermal conductivities of the different materials are as follows: k₁k3 18 W/mK, k2 6 W/mK, k4= 25W/mK, and ks - 28 W/mK. Air flows on the left and right sides of the composite wall with temperatures and convection coefficients as shown on the figure. Assuming only heat transfer through the wall (i.e. neglecting heat transfer around the edges of the wall): a) Sketch the thermal resistance diagram of system (15 marks) b) Calculate the total heat transfer rate through the wall (35 marks) 3 cm,2 am 3 cm, Tool = 80°C 3 h₁ = 45 W/m²K 1 2 S 4 24 cm 8 cm T2 = 20°C = 6cm h₂ 10 W/m²K 2 cm