Aside from simple blending processes, most chemical processes involve a temperature change in one way or another. For example, products may need to be heated to facilitate a reaction, or cooled to control reaction rate. Many of these applications involve using a heat exchanger to add or remove heat from the process fluid.

One of the most common pieces of equipment in many industries is a heat exchanger. As its name implies, it is designed to move heat from a process fluid to another fluid — which might be liquid or air. The process fluid is heated or cooled as the application demands. The transfer fluid might be air or a liquid, also as the application demands.

When heat must be dissipated from a process fluid — either liquid or gas — it is usually transferred to another fluid — either liquid or gas — using a heat exchanger. The two most common types of heat exchangers are liquid-to-liquid and liquid-to-air.