How Does a Plate Heat Exchanger Work?
The fundamental principle is indirect heat transfer through conduction. Here’s a step-by-step breakdown:
- Plate Stack: Multiple plates are clamped together in a frame between a fixed “frame plate” and a movable “pressure plate.”
- Gaskets: Each plate has a gasket that seals the channels and directs the fluids. The gasket pattern is designed so that the two fluids flow in alternating channels.
- Flow Pattern: The most common flow pattern is counter-current flow. The hot fluid flows down one set of channels, while the cold fluid flows in the opposite direction through the adjacent channels. This configuration is the most efficient for heat transfer.
- Heat Transfer: As the fluids flow through their respective channels, heat from the hot fluid passes through the thin metal plate into the cold fluid.
- Separation: The gaskets ensure the two fluids never mix, keeping them completely separate throughout the process.
The corrugated or wavy pattern on the plates (often called “herringbone”) is crucial. It serves three main purposes:
- Increases Turbulence: This disrupts the fluid flow, breaking up the boundary layer and significantly improving heat transfer efficiency.
- Increases Surface Area: More area is available for heat to be exchanged.
- Provides Mechanical Strength: The patterns help the thin plates withstand pressure.