Heat Exchanger Suitable for Medium pressure/temperature, high efficiency?
Plate Heat Exchangers (PHEs)
This is often the go-to choice for high-efficiency duties in medium pressure/temperature ranges.
- Why they’re efficient: Their design creates extremely high turbulence and thin fluid films on both sides, which results in outstanding heat transfer coefficients—typically 3 to 5 times higher than a shell and tube exchanger.
- Pressure & Temperature Range:
- Gasketed PHEs: Suitable for up to ~25-30 bar and 150-200°C (limited by the gasket material).
- Brazed PHEs (BPHE): Suitable for up to ~30-45 bar and 200-250°C.
- Welded PHEs (e.g., Compabloc, Shell-and-Plate): Can handle up to ~40-60 bar and 300-350°C, bridging the gap between gasketed PHEs and shell and tube.
- Advantages:
- Very High Efficiency: Approach temperatures (the difference between the hot outlet and cold inlet) can be as low as 1°C, maximizing heat recovery.
- Compact Size: Requires far less floor space than an equivalent shell and tube unit.
- Modularity: Capacity can be easily increased by adding more plates.
- Low Fouling: High turbulence reduces fouling.
- Disadvantages:
- Gasket Limits: Gasketed types have lower pressure/temperature limits and may not be suitable for certain fluids.
- Cleanability: Welded and brazed types are difficult to clean mechanically.
- Ideal For: HVAC, district heating, beverage processing, and any liquid-to-liquid heat transfer where efficiency and space are priorities.
2. Compact Heat Exchangers (Specifically Plate-Fin)
These are the champions of efficiency in gas-to-gas or gas-to-liquid applications.
- Why they’re efficient: They feature very high surface area density (e.g., 1000+ m²/m³) due to finned passages, leading to exceptional effectiveness (often >90%).
- Pressure & Temperature Range: Typically suitable for medium pressures (up to ~60 bar) and temperatures (up to ~500-600°C, depending on the braze material).
- Advantages:
- Extremely High Effectiveness: The best choice for recovering heat from gas streams due to the extended surface area.
- Very Lightweight and Compact.
- Disadvantages:
- Susceptible to Fouling: Cannot handle dirty or fouling fluids; requires very clean streams.
- High Cost: Complex and expensive manufacturing.
- Cannot be Cleaned: Typically discarded if fouled or leaking.
- Ideal For: Aerospace, cryogenic air separation, natural gas liquefaction (LNG), and gas turbine recuperators.