PROBLEM 1.1 KNOWN: Heat rate, q, through one-dimensional wall of area A, thickness L, thermal conductivity k and inner temperature, T 1 . FIND: The outer temperature of the wall, T 2 . SCHEMATIC: ASSUMPTIONS: (1) One-dimensional conduction in the x-direction, (2) Steady-state conditions, (3) Constant properties. ANALYSIS: The rate equation for conduction through the wall is given by Fourier’s law, q q q A = -k dT dx A = kA T T L cond x x 1 2 = = ′′ ⋅ ⋅ - . Solving for T 2 gives T T q L kA 2 1 cond = - . Substituting numerical values, find T C- 3000W 0.025m 0.2W / m K 10m 2 2 = × ⋅ × 415 T C - 37.5 C 2 = 415 T C. 2 = 378 < COMMENTS: Note direction of heat flow and fact that T 2 must be less than T 1 .