Question

A three-layer wall is constructed with the outside layer (left) being 0.1 m of stainless steel, the middle layer being 0.3 m of polypropylene, and the inside layer being 0.2 m of aluminum. Let the outside temperature far from the wall be 200 °C, and let the inside temperature far from the wall be 25 °C. The heat transfer coefficient at both walls is 0.2 W m 2K-1. 1. Calculate the steady-state temperature profile between the outer wall surface and the inner wall surface using Eqs. (2) and (3). 2. Plot the steady-state temperature profile between the outside surface and the inside surface. 3. What are the steady-state temperatures at the outer wall surface and the inner wall surface?

Answer 1

K(steel)= 50W/mC

K(polypropylene) = 0.15W/mC

K(aluminium)= 200W/mC

h (inside , outside) = 0.2W/m2C

4.0.2 To-2000 T h = 0.2 dim - 3.to 0.3m 0.2 m-> - if we draw equivalent cucuit chassam - conneches heat flux = q c 2 T @ conduction heat-flame - 9 DT SO T= 2000 menntun tunan to 256 at steady-state the heat all parts flex will be same throughout the 80 q = -K (T7 - 11) - - Kdt - dx = for second slab q. K. d = K ( Te - To) -k(-7) sleady stale temperature poble.

if we know the threemal Condu twity of all the species K stainless steel = golnic K polypropylene = 0.15 w/mc Kal= 200 wmc AW 200 un s 0.002 2 0.001 5 Rotal = 5+ 0.002 +2+ o.oolto5= 12.003. 80 E 12.003 12.003 14.60 W m2 ! 5.5 Temperatuec of inner wall 9 _ 14.60= 0.2 (T-25) Ti= 73+25 Ti = 98°c I W 1460= 0.2 (200-T.) 1 To = 127°C