A heat exchanger is a device used to exchange heat between one or more heat carriers. The heat transfer fluids can be separated by plates to prevent mixing or direct contact between the fluids.

To achieve efficiency, the heat exchanger is designed to maximize the heat transfer surface, reducing the resistance between the heat carriers as much as possible. The efficiency of the device can be increased by adding plates and corrugations on one or both sides, increasing the surface area, and changing the amount of flow.