Register to reply 
Heat transfer through wall  Insulation thickness 
Share this thread: 
#1
Dec1611, 05:24 AM

P: 2

Alright, chemistry student here. No previous experience with these types of problems. Doing an interdisciplinary student project where we have to insulate a thin aluminum wall.
http://i.imgur.com/8ztNq.gif We have a x=5mm thin aluminium wall used for dividing two air flows. T1=308 K and T2=283 K. Aluminium has a thermal conductivity of k=220 W/m,K. Assuming the wall areas are 1 m^{2} we can use the equation 1/U=(1/h1)+(x/k)+(1/h2) to determine the overall heat transfer coefficient U [W/m^{2}K]. What are some reasonable values for the heat transfer coefficients h_{1} and h_{2}? If we have these values we can calculate the heat flow Q [W] through the wall. For instance, using h1=60 W/m^{2}K and h2=40 W/m^{2}K, we get Q=U*dT=600 W. Now say we want to put a thermal barrier coating on the hot side of the wall so that the wall temperature, Tw1, goes up by 10 K. The coating has a very low thermal conductivity of k=0.02 W/m,K. Is there a way to estimate how thick the coating needs to be to achieve this? Is there enough info to solve this, or do we need more numbers? Does the heat transfer coefficient h_{1} change when we apply an insulation layer? Any help or tips would be greatly appreciated! 


#2
Dec1911, 08:44 PM

P: 15

What type of heat transfer are you doing? Conduction,convection,radiation this is going to determine the equation. I'm not sure you are using the correct equation as I do nit know what type of heat xfer it is



#3
Dec2011, 07:47 AM

P: 851

Thermal Conduction
I haven't done much with insulation, and I don't really feel like crunching numbers, but you'll either have to pick a desired delta T (or Q or whatever you want) or you'll have to do iterations until you are satisfied. Excel worksheets usually work pretty well for stuff like this. 


Register to reply 
Related Discussions  
Heat transfer problem  not given tube thickness  Engineering, Comp Sci, & Technology Homework  2  
Question about insulation and heat transfer  Classical Physics  2  
Questions about insulation and heat transfer  General Physics  7  
Heat Transfer from metal wall  Engineering, Comp Sci, & Technology Homework  0  
Effect of thickness on heat transfer/insulation  Classical Physics  11 