Plate heat exchangers (PHE)

Plate heat exchangers (PHEs) form a broad family of devices designed to transfer heat efficiently between fluids by utilising thin metal plates. Although they share the same basic principle – heat transfer via corrugated plates – the designs vary considerably depending on pressure, temperature, maintenance requirements and the properties of the fluids.

Different types of plate heat exchangers:

1. Gasketed Plate Heat Exchangers (GPHE)
   This is the most common and versatile type. Plates are arranged in parallel within a frame, with elastomeric gaskets between the plates. The fluids flow through alternating channels.
   
   Characteristics:
   – Easy to open for cleaning or replacement
   – Highly configurable (plates can be added or removed)
   – Limited by the gasket material (temperature and chemical resistance)
   
   Applications:
   – HVAC systems
   – Food industry
   – General industrial heat recovery
   
   
2. Brazed Plate Heat Exchangers (BPHE)
   Plates are permanently joined by soldering (often with copper or nickel), without gaskets.
   
   Characteristics:
   – Compact and robust
   – No risk of leakage due to gaskets
   – Cannot be dismantled
   
   Applications:
   – Cooling systems
   – Heat pumps
   – Tap water systems
   
   
3. Welded plate heat exchangers
   This design completely eliminates the need for gaskets by using welding. Both fully welded and semi-welded versions of this heat exchanger are available.
   
   Fully welded:
   The plates are fully welded together to form a solid block.
   – Suitable for corrosive media and extreme conditions
   – No risk of gaskets failing
   – Difficult to clean
   
   Semi-welded:
   Plates are welded in pairs (cassettes), with gaskets between the pairs.
   – One medium flows through welded channels
   – The other flows through channels with gaskets
   
   Applications:
   – Chemical industry
   – Oil and gas
   – Refrigerants such as ammonia
   
   
4. Plate & Shell (PSHE)
   A hybrid of plate and tube heat exchangers, in which a welded plate pack is housed within a cylindrical shell.
   
   Characteristics:
   – Combines the efficiency of plate heat exchangers with the pressure resistance of welded heat exchangers
   – Highly resistant to thermal stresses
   
   Applications:
   – Petrochemical industry
   – High-pressure steam applications
   
   
5. Spiral heat exchanger
   They are spiral-shaped, unlike other plate heat exchangers. Two metal plates are rolled up to form spiral-shaped channels. The advantage is that this heat exchanger is resistant to fouling, but it is less flexible and difficult to scale up.
   
   Characteristics:
   – One channel per medium reduces blockages
   – Self-cleaning effect due to flow
   
   Applications:
   – Wastewater treatment
   – High-viscosity liquids or liquids containing solid particles (slurries)