# Heat Transfer Application examples of using fins

• Hannibal247
In summary, the conversation discusses the creation of thermal circuits and the equations for calculating heat rate for different configurations. The thermal circuits for b) and c) are parallel connected, while for a), the heat rate on the chip side and board side are different due to different resistance values. The correct equation for the heat rate in this case is Q = Ab2 * 1/((1/hi)+(Lb/kb)+(1/he)).
Hannibal247
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Hello,
Im struggling a bit with this problem. (uploaded)
I don't know how to sketch the equivalent thermal circuit for any of them. Does it have to look like anything like that?

the thermal circuits are for b) parallel connectd right? and for aswell?
And I am getting wrong answers for a). Shouldnt it be like this?
Q= he*Ab2*55 + 1/((1/hi)+(Lb/kb))*Ab2*55
or are they all parallel? like this Q=Ab2*1/((1/hi)+(Lb/kb)+(1/he)) .
My first thought was that the heat rate dissipating on the chip side is the same as the heat rate on the board side. why is this thought wrong? I am confused :D
Best regards

Yes, the thermal circuits for b) and c) are parallel connected. For a), the heat rate dissipating on the chip side is not the same as the heat rate on the board side. This is because the resistance of the board (Lb/kb) is different than the resistance of the chip (1/he). Thus, the heat rate will be different on each side. The correct equation for the heat rate is: Q = Ab2 * 1/((1/hi)+(Lb/kb)+(1/he))

## 1. What are fins used for in heat transfer applications?

Fins are used to increase the surface area of an object in order to enhance heat transfer. This is particularly useful in situations where the available surface area for heat transfer is limited, such as in electronic devices or heat exchangers.

## 2. What are some common examples of fins in heat transfer applications?

Some common examples of fins in heat transfer applications include computer heat sinks, car radiators, and air conditioning units. They can also be found in household appliances such as refrigerators and ovens.

## 3. How do fins improve heat transfer efficiency?

Fins improve heat transfer efficiency by increasing the surface area in contact with a fluid, such as air or water, which allows for more heat to be transferred from the object. This is achieved through the process of convection, where the fluid transfers heat away from the object as it flows over the fins.

## 4. Are there different types of fins used in heat transfer applications?

Yes, there are different types of fins used depending on the specific application and requirements. Some common types include straight fins, annular fins, and pin fins. Each type has its own advantages and disadvantages in terms of heat transfer efficiency and cost.

## 5. What are some factors to consider when designing fins for heat transfer applications?

When designing fins for heat transfer applications, some important factors to consider include the material properties, fin geometry and dimensions, and the type of fluid and flow conditions. These factors can greatly affect the performance and efficiency of the fins, so careful consideration is necessary for optimal design.

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