Question

Problem Wall with Strip Heater The air inside a chamber is measured to be 50C and used to convectively heat a wall (h 20 w/m2 K). The wall (thermal conductivity of 4 W/m K) is 200 mm thick and has a uniform heat generation of 1000 W/m2. To prevent any heat generated within the wall from being lost to the outside of the chamber a very thin electrical strip heater is placed on the outer wall to provide a uniform heat flux, qo". The air in the outside chamber is characterized as follows: temperature 25 C, coefficient of the convection 5 w/m2 K) Strip heater, q" Wall, k, q Outside chamber Inside chamber T, o ho oo, i Determine the following: Assuming the no heat is lost to the outside chamber, determine the temperatures on the faces of the wall (x-0 and x-L) Estimate the value of heat flux that must be supplied by the strip heater so that all heat generated within the 1. 2. wall is transferred to the insides of the chamber. 3. If the heat generation in the wall were switched off while the heat flux to the strip heater remained constant, what would the steady-state temperature of the outer wall surface (T at x-0)?

Answer 1

Goveaning d2 TT x2 CO a Fnom (1) Ensngy balance! h [2-T; iL20 So + 1000xo.2. o C2 2. F1om (22 !- 2 ; T:T, !' 4- * ,59ミ TTI FSom (2) 17 At 0 TToo0 6S 2.5 200 (b) 15 c7dith mm. e hi ao T/ho T2S /4-