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Shell-and-Tube Chilled Water Evaporator Tube Freeze Damage — During Winter Shutdown

Likely causes

Ambient temperature drop without draining chilled water side

Check: freeze expansion cracks copper tubes

What to do: Locate leak — pressurize chilled water side with nitrogen (0.5 MPa) to identify leaking tubes; plug individual tubes before considering full bundle replacement

Insufficient antifreeze (glycol) concentration

Check: freezing above design freezing point

What to do: Insert stainless steel taper plugs at both ends of damaged tubes and weld seal; plugging up to 10% of total tubes is within performance tolerance

No circulation after chilled water pump stops

Check: stagnant water freezes locally

What to do: Measure glycol concentration with a refractometer — verify freeze protection to at least –10 °C (approx. 30% ethylene glycol); adjust as needed

Long shutdown with TXV/solenoid valve open on refrigerant side

Check: residual liquid refrigerant causes sub-zero temperatures

What to do: Inspect freeze protection heater — confirm controller setpoint at +5 °C, measure resistance to check for heater burnout

Deteriorated insulation transmitting outdoor cold directly to piping

Check: Inspect with instruments or visually

What to do: Install automatic drain valve (motorized ball valve) on chilled water side — add circuit to open automatically when outdoor temp reaches –3 °C

Field tip

Performance loss estimate after plugging: each plugged tube reduces effective heat transfer area by approx. 1%. Up to 10% plugging means only 1–2% capacity loss — operation can continue.

All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.

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