What is Plate and Frame Heat Exchanger?
What is a Plate and Frame Heat Exchanger (P&FHE)?
A Plate and Frame Heat Exchanger is the most common type of gasketed plate heat exchanger (gasketed PHE). It consists of a pack of corrugated metal plates clamped together in a frame. The name “plate and frame” specifically describes this style, which has a removable, serviceable frame, distinguishing it from brazed or welded plate exchangers.
Core Principle: Two fluids flow on either side of thin, corrugated metal plates. Heat is transferred from the hot fluid to the cold fluid through the plate material. The plates are sealed by gaskets, which also arrange the flow of the fluids into alternating channels.
Key Components and Their Functions
The design is modular and relatively simple, comprising three main groups of parts:
1. The Frame (The Support Structure):
- Fixed Frame Plate (Head): A heavy, stationary plate to which the carrying bar and guide bar are connected. It has inlet and outlet ports for the fluids.
- Movable Pressure Plate: The plate at the other end that can be moved along the carrying bar. When the unit is tightened with bolts, this plate compresses the plate pack to form a seal.
- Upper Carrying Bar & Lower Guide Bar: Support the plate pack and ensure the plates are aligned correctly when the unit is assembled or opened.
2. The Plates (The Heat Transfer Surface):
- Plates: Thin sheets of metal (typically stainless steel 316, titanium, or other alloys) pressed with a corrugated (wavy) pattern. This pattern serves critical functions:
- Increases Turbulence: Disrupts laminar flow, drastically improving heat transfer efficiency.
- Enhances Strength: Adds rigidity to the thin plates to withstand pressure.
- Provides Contact Points: Ensures the correct gap is maintained between plates.
- Port Holes: Holes in the corners of each plate that align to form continuous passageways for the two fluids to enter and exit the plate pack.
3. The Gaskets (The Sealing System):
- Gaskets: Elastomer seals fitted around the ports and the perimeter of each plate. They are the key to the design’s flexibility and serviceability. They have two jobs:
- Prevent Leakage: Seal the fluids within their channels and prevent them from mixing.
- Direct the Flow: The specific arrangement of the gaskets (see image below) ensures that the two fluids are directed into alternating channels without ever mixing.
Common Applications
Plate and Frame Heat Exchangers are used wherever efficient, compact, and serviceable heat transfer is needed:
- HVAC: District heating and cooling systems, heat recovery loops.
- Food & Beverage: Pasteurization of milk, juice, and beer. Their cleanability meets strict sanitary (3-A) standards.
- Marine Industry: Central cooling systems for engine jacket water.
- Chemical Industry: Heating and cooling of process streams where the fluid is not overly viscous or particulate-laden.
- Power Industry: Cooling hydraulic oil and closed-loop water systems.
- Pharmaceutical: Requires sanitary conditions and clean-in-place (CIP) capabilities.