Hot combustion gases of a furnace are flowing through a square chimney made of concrete (k = 1.4 W/m-K). The flow section of the chimney is 20 cm x 20 cm, and the thickness of the wall is 20 cm. The average temperature of the hot gases in the chimney is T, = 300°C, and the average convection heat transfer coefficient inside the chimney is h; = 70 W/m-K. The chimney is los ing heat from its outer surface to the ambient air at T = 20°C by convection with a heat transfer coefficient of h,= 21 W/m2K and to the sky by radiation. The emissivity of the outer surface of the wall is e=0.9, and the effective sky temperature is estimated to be 260 K. Using the finite difference method with Ax = Ay = 10 cm and taking full advantage of symmetry, determine the tem pressure at the nodal points of a cross section and the rate of heat loss for a 1-m-long section of the chimney.