Structure and working principle of plate heat exchangers

A plate-and-tube heat exchanger consists of two main parts: The plate-tube bundle and the shell. The plate bundle is equivalent to the tube bundle in a shell-and-tube heat exchanger. Each plate bundle element is formed by pairing two cold-pressed (or explosion-formed, etc.) metal strips welded tightly together at the contact point, creating a plate-tube structure containing multiple flat flow channels.

In the heat exchanger, these flat plate-tube flow channels constitute the plate side of the plate-and-tube heat exchanger, equivalent to the tube side in a shell-and-tube heat exchanger, while each plate bundle element is equivalent to a tube. Many plate tubes of varying widths are arranged in a specific order. To maintain the spacing between the plate tubes, metal strips are inserted into the ends of adjacent plate tubes and welded to them.

The ends of the plate tubes form tube sheets, thus securely connecting many plate tubes to form the plate-tube bundle. The end faces of the plate-tube bundle exhibit several flat flow channels. The spacing between the plates in the bundle is maintained by recesses on the plate bundle elements. The plate-tube bundle is assembled inside the shell, and the longitudinal expansion difference between it and the shell is eliminated by a sliding seal. The cross-section of the equipment is generally circular, but there are also rectangular, hexagonal, etc.