Brazed Plate Heat Exchanger Freeze Fracture

Question

Accepted Answer

Insufficient water flow (below 30% of rated, < 5 L/min). Check: stagnant water freezes What to do: Check water flow: measure inlet/outlet differential pressure (normal 20~40 kPa), confirm flow ≥ 5 L/min with flowmeter Refrigerant evaporating temperature too low (setpoint error below -10°C, EEV over-open). Check: Inspect with instruments or visually What to do: Adjust EEV superheat setpoint: target SH 5~8 K, reduce opening to maintain evap temp ≥ -5°C Water pump stops under low load while refrigerant continues circulating. Check: residual water freezes What to do: Verify interlock logic: water pump off → refrigerant pump/compressor off simultaneously Inadequate pipe insulation in winter. Check: water freezes at plate inlet What to do: Replace damaged BPHE and reinstall insulation (≥ 25 mm thickness) on inlet/outlet pipes Poor water quality (scale > 0.5 mm). Check: flow channel blockage → localized freezing What to do: Scale inspection: clean annually with 10% citric acid solution circulating for 30 minutes

Brazed Plate Heat Exchanger Freeze Fracture

Likely causes

Insufficient water flow (below 30% of rated, < 5 L/min)

Refrigerant evaporating temperature too low (setpoint error below -10°C, EEV over-open)

Water pump stops under low load while refrigerant continues circulating

Inadequate pipe insulation in winter

Poor water quality (scale > 0.5 mm)

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