Choose a Plate Heat Exchanger when:
- Space is limited.
- The fluids are fouling (like cooling tower water or viscous liquids).
- The approach temperature is very close (e.g., cooling a liquid from 40°C to 20°C with water entering at 15°C).
- The fluids are clean or contain only small particles.
- Pressures are below 25 bar and temperatures below 150°C (for gasketed types).
- You need the ability to easily clean or modify the heat transfer area.
Choose a Shell and Tube Heat Exchanger when:
- Pressures are very high (e.g., in power plants or high-pressure chemical processes).
- Temperatures are very high (e.g., superheated steam).
- One of the fluids contains large particulates, fibers, or is a gas that can be routed on the shell side.
- Robustness and a proven design are the top priorities for a critical, high-duty application.
- The application involves phase change (condensation, vaporization), though specialized plate designs are now competing in this area.