What is the Conduction Heat Transfer? Important Terms About Conduction

What is the Conduction Heat Transfer? Important Terms About Conduction

Heat transfer is a very important topic in mechanical engineering and other engineering disciplines. In most engineering applications, heat transfer calculations are used a lot. For example, insulation problems of systems, internal combustion engines heat on digital cards of systems… 

There are different heat transfer mechanisms and one of them is conduction heat transfer. Here, you can find brief information about the conduction heat transfer mechanism. 

What is the Conduction?

Convection is a heat transfer mechanism in which heat transfer takes place between the higher energy of molecules to the lower energy of molecules of materials. In gases, convection heat transfer takes place by the collision of the molecules. This conduction mechanism is also valid for liquids. 

In solids, conduction heat transfer takes place with the transferring of heat energy with vibrational motions of molecules and atoms. 

Different parameters affect the conduction heat transfer mechanism in engineering systems. 

Geometry

One of these parameters is the shape of the system. For example, the thickness of the material affects the heat transfer. With the increasing thickness, the decreasing heat transfer rate between mediums. 

Also, an increasing area where conduction heat transfer takes place between two mediums means, increasing total conduction heat transfer.

Temperature Difference

In conduction heat transfer between two mediums separated by material or wall, the temperature difference is a very important parameter. With the increasing temperature difference between mediums, an increasing amount of conduction heat transfer between the mediums. 

Material

The type of material that is used between mediums is also a very important parameter in conduction heat transfer. The abilities of conduction heat transfer of different materials differ from each other. 

Fourier’s Law of Heat Conduction

This formula clarifies the heat transfer with the conduction phenomenon; 

Here, ‘k’ is the thermal conductivity of the material and ‘T2’ is the temperature of the other region. ‘T1’ is the temperature of the inner region where conduction heat transfer takes place. and ‘x’ is the thickness of the insulation material.

The unit of this formula is ‘Watt’. 

Thermal Conductivities of Materials(k)

Thermal conductivity states the ability of a material that conducts heat. For example, the thermal conductivity of water is 0.60W/m.K, and the thermal conductivity of iron is nearly 80W/m.K. This means that metal conducts heat 100 times better than water. 

Image Source: Yunus A. Çengel, Afshin J. Ghajar – Heat and mass transfer, fundamentals and applications-McGraw-Hill Education, 5th Ed.

Thermal Diffusivities of Materials(α)

The thermal diffusivity of a material is equal to the ratio of thermal conductivity to heat storage. 

If material has high thermal conductivity and low diffusivity, that material has high thermal diffusivity in which heat can propagate inside it. 

Conclusion

Heat conduction in the heat transfer discipline can be explained as above. 

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