You’ve heard of the phrase “heat exchanger.” You may know it refers to a process governed by the Second Law of Thermodynamics. And you may even know a common usage or two. But heat exchangers are known as a central part of many different mechanical objects, including one that is immediately recognizable.
Heat exchangers are used to transfer heat between two or more fluids, between a solid surface and a fluid, or between solid particulates and a fluid, at different temperatures and in thermal contact. The most apparent example is in your HVAC system: The air coils take hot air from the outside atmosphere and cool it down.
When it comes to the design of the heat exchanger, there are at least three worth noting, and they vary depending on the nature and timing of the flow of the liquids.