A plate heat exchanger is a type of heat exchanger. Heat exchangers are also called heat transfer devices. The term is appropriate because, during the process, there is no exchange of heat itself, but rather a transfer of heat from one medium to another.

The plate heat exchanger consists of wavy plates that are assembled in a unique way. Between the plates, there are gaps. In these intermediate spaces, two media circulate alternately: the heat absorption medium and the heat diffusion medium. The device is sealed both on the outside and underneath the media, which can be achieved in various ways.

There are screw plate heat exchangers that are expandable and transfer flow differently. The preferred types are the modular plate heat exchangers, which are characterized by the fact that the various plates are welded together.