Absorption Chiller Vacuum Loss — Non-condensable Gas Accumulation

Question

Accepted Answer

Purge unit failure — non-condensable gas not removed, internal pressure exceeds 5 torr. Check: Manually operate purge unit for 5~10 min and check vacuum gauge pressure change — normal if pressure returns to below 5 torr. If gauge continuously rises (>0.1 torr/hr), suspect pipe leak or purge unit failure What to do: Check purge unit electrical system (solenoid valve, vacuum pump operation) → replace faulty parts. If non-condensable gas is severe, request professional re-evacuation (<10 Pa) and refrigerant water recharge service Vacuum line leak in absorber or condenser section. Check: Inspect all vacuum lines with helium leak detector — check flanges, welds, and service valves in order. Pressure rise rate: if leaking, pressure rises >0.1 torr/hr What to do: Repair leak by welding or replacing packing and gasket. After repair, re-evacuate and verify target vacuum — evaporator 3~5 torr, absorber 4~6 torr LiBr solution concentration drop or cooling water overheating causes poor absorption. Check: Sample LiBr solution — check concentration 55~60% (normal), pH 9.5~10.5. Measure cooling water inlet temperature — above 32°C causes poor absorption and gas separation What to do: If LiBr concentration is abnormal, adjust by diluting with distilled water or adding LiBr. Check and replenish corrosion inhibitor (lithium chromate 0.3%). Adjust cooling water inlet to 29~32°C — check cooling tower operation

Absorption Chiller Vacuum Loss — Non-condensable Gas Accumulation

Likely causes

Purge unit failure — non-condensable gas not removed, internal pressure exceeds 5 torr

Vacuum line leak in absorber or condenser section

LiBr solution concentration drop or cooling water overheating causes poor absorption

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