Exchangers built as a corrugated metal plate pack stacked alternately. The two fluids flow in adjacent channels formed between plates, separated by gaskets or welds. High thermal effectiveness with little volume and mass — a fraction of the size of an equivalent shell-and-tube.
Usual types
- Gasketed — pressed plates with elastomeric gaskets; disassemblable for cleaning; moderate service (< 25 bar, < 180 °C); standard in chilled water, HVAC, dairy.
- Brazed — plates brazed with copper or nickel; compact, non-disassemblable; refrigeration, hydraulic oil.
- Fully welded — coiled plates TIG-welded; support severe service; petrochemical and fine chemistry.
Reliability: gasket degradation (in gasketed units — the dominant mode, life in operating hours and temperature), localized corrosion at plate ribs, fouling in narrow channels (more critical than in shell-and-tube due to the smaller cross-section). Frequent CIP cleaning in most services.