Thermal Resistance To Conduction

Originally derived from Fourier’s law for heat conduction, thermal resistance to conduction is an important concept to cover. Thermal resistance to conduction is defined as the ratio of president temperature between two phases of a material to the rate of flow of heat per unit area. 

In this article, we will understand the topic of thermal resistance to conduction and its relevance to the course. The article will also cover several other important concepts that are directly or indirectly related to thermal resistance.

So, without further ado, let us get started with the discussion!

Thermal Resistance Fundamentals

As we start with the topic, let us first get well-versed with the fundamentals. Thermal resistance to conduction refers to the heating property of a material by which it resists heat flow. It is the opposite or the reciprocal of thermal conductivity. We can also explain it as the quantification of how difficult it would be for a material to conduct heat.

Thermal resistance is also expressed as the quotient of the difference in temperature between two given points and the flow of heat between them. It implies that the higher the level of thermal resistance, the more difficult it would be for the material to conduct heat.

Role of Ohm’s law

The thermal resistance to conduction can also be seen in the same way as electric resistance. In this way, we can also use the basic formula of thermal calculation to represent the illustrations and equations. 

Therefore, the temperature difference can also be calculated by keeping the potential difference in mind. However, in the case of thermal resistance for thermal conduction, keeping one end of the object in cross-section is mandatory. It would help the opposite end reach through it and influence the temperature. Thus, it is crucial to understand the role of Ohm’s law when it comes to thermal resistance.

Thermal Resistance Analogy

Understanding the concept of thermal resistance to conduction also provides an opportunity to analyse several heat transfer problems with reference to the electrical analogy. It can also help visualise and analyse the complicated systems related to Ohm’s law.

Let us take a moment to understand this. 

As given by Ohm’s law –

V=IR

In this relation, V represents the voltage that drives the magnitude. The amount of current flowing for the given voltage is directly proportional to the resistance. However, the resistance also depends on the material properties and physical configuration in the case of an electrical conductor. For instance, copper usually has lower resistance in comparison to wood. 

It is also important to know that heat flow is also proportional to the difference in temperature with steady-state heat transfer without any internal heat generation and can be represented by the equation – Q = kA∆T/∆x

Here, Q stands for the amount of heat flow, k refers to the material property of thermal conductivity, and A represents the area that is normal to the flow of heat. Further, ∆x denotes the distance surrounding the heat flow, and ∆T refers to the difference in temperature fueling the heat flow. 

Advantages 

Now that we know the meaning of thermal resistance to conduction let us discuss a few advantages of applying thermal resistance formulations. Here are a few pointers to illustrate:

Simplification in problem setup

Application of thermal resistance formulation can help to simplify the arrangement of complex problems. For instance, while calculating the heat flow for the temperature of the liquid stream, the equation set-up becomes easier if the material properties match. 

It would be necessary to involve a more simplified solution because the radiator thermal resistance has surface temperature inside it. This can further help to keep the process simple.

Deep insights into the problem

The application of thermal resistance formulation to conduction also helps get informative insights into the problem. It helps us understand which parts of the model are responsible for controlling the heat transfer and which parts do not hold much relevance.

Let us understand this scenario through an example. If thermal resistance on the given liquid material is 20 k/w with 1 mm plastic as composite wall and thermal resistance of 40 k/w, the thermal resistance to radiation and conduction will come with a lower emissivity. 

Conclusion 

In conclusion, we can say that thermal resistance to conduction is the reciprocal phenomenon of what we understand by the thermal conductivity of a given material. However, it would not be wrong to point out that it is an equally powerful concept to help us understand complicated processes and apply relevant solutions. As discussed above, it can also help experiment with the existing technologies to bring up the solutions that can bring revolution in the world of technology.