Heat transfer through wall - Insulation thickness

In summary, a chemistry student with no previous experience in these types of problems is working on an interdisciplinary student project to insulate a thin aluminum wall. Using the equation 1/U=(1/h1)+(x/k)+(1/h2), where T1=308 K, T2=283 K, k=220 W/m,K, and wall area is 1 m2, the overall heat transfer coefficient U [W/m2K] can be determined. Reasonable values for heat transfer coefficients h1 and h2 (such as h1=60 W/m2K and h2=40 W/m2K) can then be used to calculate the heat flow Q [W] through the wall. To increase the wall temperature on
  • #1
klopjob
2
0
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 m2 we can use the equation

1/U=(1/h1)+(x/k)+(1/h2)

to determine the overall heat transfer coefficient U [W/m2K].

What are some reasonable values for the heat transfer coefficients h1 and h2? If we have these values we can calculate the heat flow Q [W] through the wall. For instance, using h1=60 W/m2K and h2=40 W/m2K, 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 h1 change when we apply an insulation layer? Any help or tips would be greatly appreciated!
 
Engineering news on Phys.org
  • #2
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
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.
 

FAQ: Heat transfer through wall - Insulation thickness

1. What is heat transfer through wall?

Heat transfer through wall refers to the process by which heat energy is transferred from one side of a wall to the other. This can occur through conduction, convection, or radiation.

2. How does insulation affect heat transfer through wall?

Insulation is designed to reduce heat transfer through walls by providing a barrier that slows down the movement of heat. Thicker insulation can provide a greater resistance to heat transfer, resulting in lower energy costs and improved temperature control in a building.

3. What is the relationship between insulation thickness and heat transfer?

The thicker the insulation, the lower the rate of heat transfer through a wall. This is because a thicker layer of insulation provides a greater resistance to the movement of heat, making it more difficult for heat to pass through the wall.

4. How do different types of insulation affect heat transfer through wall?

Different types of insulation, such as fiberglass, foam, or cellulose, have different thermal conductivities which affect their ability to resist heat transfer. Additionally, the installation method and quality of installation can also impact the effectiveness of insulation in reducing heat transfer through walls.

5. Is thicker insulation always better for reducing heat transfer through wall?

While thicker insulation generally provides better resistance to heat transfer, there are other factors to consider such as cost, space limitations, and climate. In some cases, adding too much insulation can result in diminishing returns, where the additional cost and space may not significantly improve the insulation's effectiveness.

Back
Top