The plate heat exchanger is composed of a set of corrugated stainless steel metal plates with holes in the corners of the heat transfer plate for the passage of two heat transfer fluids. The heat transfer principle of heat exchanger is basically divided into three forms: hybrid, heat storage and partition heat transfer. The heat transfer principle of the plate heat exchanger is the dividing wall heat transfer principle.
(1) Convection heat transfer
Convection and heat conduction are both basic methods of heat transfer. For the heat transfer process in engineering, the fluid is always in direct contact with the solid wall. Therefore, the transfer of heat relies on the continuous movement and mixing of fluid particles (convection). On the other hand, it relies on the heat conduction caused by the temperature difference between the fluid and the solid wall and the fluid everywhere. This process in which convection and heat conduction exist simultaneously is called convective heat transfer.
(2) Phase change heat
In the convection heat exchange, the heat exchange process of the condensation of steam or the boiling or evaporation of liquid occurs, which is collectively referred to as phase change heat. Since the state of matter changes during this type of heat exchange process, the situation is much more complicated than convective heat transfer in a single-phase fluid, and the general convective heat transfer problem only refers to single-phase fluids.
(3) Heat conduction
In the plate heat exchanger, the heat transfer of the plates and the scale layer is heat conduction. Since the thickness of the plate and the scale layer is small compared with the size of the plate surface, the heat conduction process can be regarded as one-dimensional heat conduction along the thickness direction.