Overall Thermal Conductivity of Three different layers

In summary, overall thermal conductivity is a measure of how well a material conducts heat, taking into account the thermal conductivity of each individual layer and their thicknesses. It is calculated by taking the weighted average of the thermal conductivities of each layer, where thicker layers have a greater impact. The thermal conductivity of each individual layer, their thicknesses, and the interface resistance between layers are the main factors that can affect overall thermal conductivity. It can be improved by using materials with higher thermal conductivities or optimizing the thicknesses of each layer, but other factors such as cost and practicality should also be considered.
  • #1
Izazo
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TL;DR Summary
How to calculate the overall conductivity of three layers bonded with each other having different thermal conductivities?
Overall thermal conductivity?
for example, there are 3 layers made of different materials, having different thermal conductivities bonded with each other;
conductivity of layer 1= k_1 = 1 W/m-K
thickness of layer 1= t_1 = 0.004 m

conductivity of layer 2= k_2 = 148 W/m-K
thickness of layer 2= t_2 = 0.0003 m

conductivity of layer 3= k_3 = 0.23 W/m-K
thickness of layer 3= t_3 = 0.004 m
 
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  • #2
You should calculate thermal resistance of each layer, sum up resistances end recalculate compound conductivity from the sum.
 
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1. What is overall thermal conductivity?

Overall thermal conductivity refers to the measure of how well a material conducts heat through its entire thickness. It takes into account the thermal conductivity of each individual layer and how they interact with each other.

2. How is overall thermal conductivity calculated?

Overall thermal conductivity is calculated by taking the sum of the thermal conductivity of each layer multiplied by its thickness, divided by the total thickness of all layers. This can be represented by the equation: k = (k1t1 + k2t2 + k3t3) / (t1 + t2 + t3), where k is the overall thermal conductivity, k1, k2, and k3 are the thermal conductivities of each layer, and t1, t2, and t3 are the thicknesses of each layer.

3. What factors affect the overall thermal conductivity of three different layers?

The overall thermal conductivity of three different layers can be affected by various factors such as the thermal conductivity of each individual layer, the thickness of each layer, the interface resistance between layers, and the temperature gradient across the layers.

4. How does the interface resistance between layers affect overall thermal conductivity?

The interface resistance between layers can act as a barrier to heat transfer, reducing the overall thermal conductivity. This is because it creates a thermal resistance at the interface, hindering the flow of heat between the layers.

5. Why is it important to consider the overall thermal conductivity of three different layers?

Understanding the overall thermal conductivity of three different layers is important in various applications where heat transfer is a crucial factor. This includes building insulation, electronics, and industrial processes. It allows for the selection of materials with optimal thermal properties to achieve efficient heat transfer and maintain thermal stability.

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