In the wake of the Samsung Galaxy Note 7 explosion in 2016, the importance of heat transfer and efficient fin technology to solve the problem of battery overheating is discussed, and the design and cooling of mechanical components is detailed.
A long time ago, in 2016, the Samsung Galaxy Note 7 exploded and was recently advised not to be used due to its dangers. The incident sent shockwaves around the world and sparked a lot of discussion and research into the safety of electronic devices, particularly the safety of battery technology, which has led to many companies working to ensure the safety of their products. While the exact cause of the explosion is unknown, the most likely culprit is overheating of the battery. Battery overheating is caused by poor heat transfer to the outside. When designing and building mechanical components, it is important to take this heat transfer into account. In this article, we will give a basic explanation of heat transfer and a brief introduction to fins, which are efficient in increasing heat transfer.
What is heat transfer? To answer this question, heat transfer is the movement of thermal energy due to a temperature difference, meaning that heat is transferred when there is a temperature difference within or between two media. There are three ways that heat can be transferred: conduction, convection, and radiation. Conduction is the transfer of heat through a stationary medium, such as a solid or liquid, when a temperature gradient exists within it. For example, when you heat one end of a metal rod, heat is transferred through the metal to the other end, which is conduction. Convection is the heat transfer that occurs between surfaces of different temperatures and a moving fluid. For example, when you boil water in a pot, the heat is transferred by the circulation of the water. Radiation is heat transfer that occurs between surfaces with different temperatures without an intervening medium. The transfer of solar energy to Earth through outer space is a prime example of radiation. In order to prevent mechanical components from overheating, heat transfer between the component and the external fluid must be good. Next, we’ll look at how heat is transferred and how it is cooled in the context of mechanical component production. Among conduction, convection, and radiation, heat transfer due to radiation is of little concern because it is negligible compared to heat transfer due to conduction and convection. Therefore, we will not discuss it.
Conduction can be seen as the transfer of energy from more active particles to less active particles in a substance by interactions between particles. The equation for the heat transfer rate due to heat conduction is Fourier’s law. This law states that the rate of heat transfer due to heat conduction is proportional to the thermal conductivity, cross-sectional area, and temperature difference, and inversely proportional to distance (direction of heat transfer).
Convection is the transfer of energy by irregular molecular motion or diffusion. For example, in a heating system, warm air circulating through a room and transferring heat is a type of convection. Similarly, there is an equation for the heat transfer rate due to convective heat transfer, Newton’s law of cooling, which states that the heat transfer rate is proportional to the convective heat transfer coefficient, cross-sectional area, and temperature difference.
Based on these two laws, there are three main ways to increase the heat transfer rate in order to efficiently cool an overheated mechanical part. First, increase the thermal conductivity and convective heat transfer coefficient; second, increase the temperature difference between the part and the external fluid; and third, increase the cross-sectional area. Since thermal conductivity and convective heat transfer coefficient are properties of the material itself, increasing them can be done by making the mechanical part out of better materials. However, this comes with a price tag. Increasing the temperature difference between the part and the external fluid requires lowering the temperature of the external fluid, which is also difficult because room temperature is constant except in special cases. On the other hand, you can easily increase the heat transfer rate by increasing the cross-sectional area. The expanded surface is called a fin.
You can find fins all around you. Think of the engine cases or radiators of motorcycles and lawn mowers. There are many different shapes that can be made: straight, annular, and finned (spine-like). The choice of these shapes is determined by volume, weight, manufacturing conditions, and cost. The most important aspect of a hinge is its performance. There is no simple formula for the performance of a hinge; it is calculated using a variety of conditions at the end of the hinge, and trends can be deduced from the results. As a general rule of thumb, the thinner and more spaced out the hinge, the better the performance, as long as the gap between the hinge and the pin is not so narrow that they interfere with each other. Also, considering the thermal conductivity, weight, and price of the fins, aluminum alloys are most commonly used.
This is a basic explanation of heat transfer and a brief introduction to fins. Fins are most often used to create components where overheating can cause problems with the functioning of the part. In particular, they are essential in a variety of industries where heat needs to be managed efficiently, such as aircraft, automotive, electronics, and more. As such, heat transfer is an important factor in creating safe mechanical parts. It’s essential to consider how much a part can overheat and whether it can cool down enough to prevent it from failing. While recent advances in technology have led to the development of a wide variety of machines, it is important not to be fooled by new features and technologies, but to consider basic safety factors to prevent a repeat of the cell phone explosion. Furthermore, these technological challenges and safety measures are important lessons for future technological advancements.
