A heat exchanger is a device that transfers heat from a fluid (liquid or gas) to pass to a second fluid without the two fluids mixing or coming into direct contact. Heat exchangers are commonly used in liquid cooling systems to dissipate heat from a fluid that has passed over a cold plate attached to the heat-producing component. The cool fluid is pumped through the system and back across the cold plate.
Heat exchangers are designed to maximize the surface area of the wall between the two fluids, while minimizing the resistance to fluid flow through the exchanger. The addition of fins or corrugations in one or both directions increases the surface area and increases the heat transfer capacity of the heat exchanger.
In a shell and tube heat exchanger, one fluid flows through a series of metal tubes and the second fluid is pumped through a shell that surrounds them. The fluid flow can be either parallel (flowing in the same direction), counterflow (flowing in opposite directions) or crossflow (flows are perpendicular to each other).
Tube-to-fin heat exchangers (as shown in the GIF above) use fins surrounding two tubes that carry the fluids. The fins increase the surface area and maximize heat transfer to the ambient. Some finned tube heat exchangers use natural convection and other can include fans to increase the airflow and heat transfer capacity.
Plate and frame heat exchangers have two rectangular end members holding together a series of metal plates with holes in each corner to allow the liquids to pass through. Each of the plates has a gasket to seal the plates and arrange the flow of the fluids between the plates. Brazed plate heat exchangers avoid the potential for leakage by brazing the plates together. Plate and frame heat exchangers are commonly used in food processing.
Common applications for heat exchangers include telecommunications, process cooling, power electronics, medical device and medical imaging, automotive, industrial, and HVAC.
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