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Electronics Cooling Designs: Heat Pipes

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Electronics Cooling Designs: Heat Pipes

Electronics Cooling and Thermal Management

cpu coolerWhen electronics are run for extended periods of time they produce heat. A common example is right in front of you in the form of a computer. Managing this heat is very important to maintain efficiency and the long term life of the system. As laptop computers become more powerful yet more compact as with many electronic devices today, engineers are looking at ways to improve thermal management designs.  When space constraint is a concern for placing a heat sink directly onto a CPU such as with a laptop computer, the need to transfer that heat away to an area for cooling becomes necessary. One of the many types of electronics cooling applications for this task available today is known as a heat pipe. There are different types of heat pipes designs that are used for many applications such as, solar thermal, permafrost cooling and even in HVAC systems, we are taking a look at how they are utilized in today’s electronics fields.

Heat pipes improve heat sink cooling

Heat pipes were introduced to be used in place of forced convection or passive finned heat sinks when used in electronics cooling. Heat Pipes are essentially passive heat transfer devices with extremely high thermal conductivity; the two-phase mechanism is capable of sometimes reaching several thousand times the conductivity of an equivalent piece of solid copper. The first phase in a heat pipe is the evaporator, where heat enters the pipe and causes the working fluid to evaporate creating a pressure gradient that forces the vapor toward the second step, the condenser. Heat exits the pipe at the condenser where the working fluid condenses and releases its stored heat. A heat pipe is a pipe made of usually either aluminum or copper that is sealed at both ends and contains some sort of structure design such as grooves, known as the wick, that allows for capillary action to occur. With the vacuum inside the pipe at or below the vapor pressure, the working fluid is in a state of half gas and half liquid. As heat is generated, the working fluid evaporates and is transferred down the tube to a condenser or radiator, at which point it can be cooled. During the trip through the radiator or condenser, the heat is released and then returned to its original liquid state. The capillary action that is created by the wick allows for the liquid to be returned to the heat source and the cycle repeats itself. It is because of the evaporation and condensation of the working fluid that allows the use of heat pipes to be so effective.

Engineering improvements in electronic cooling

As I stated before, engineers are constantly working to improve electronics cooling designs and improve thermal management efficiency. One of the ways they have utilized the heat pipe design and theory, was to create thin flat heat pipe systems also known as heat spreaders. This type of cooling design works in the same way as heat pipes, but are spread out over a larger area. They are also sealed and use a working fluid with capillary action, but can be as thin as 0.5mm, making them ideal for applications that have strict size constraints, such as laptop computers and smaller electronic devices. A licensed mechanical engineer that utilizes tools such as computational fluid dynamics (CFD) and computer assisted design (CAD), can utilize 3D CAD modeling when creating new and more efficient designs to improve the thermal management of today’s smaller and faster electronic devices. By using programs such as these, the cost of research and development for creating new printed circuit boards (PCB) and other electronic components, is reduced and therefore allowing new products to be available at prices that more people can afford. It is innovation like this that has allowed us to develope technology and at a faster pace than any other time in history.


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