Air, nitrogen and other non‑condensable gas mixed inside refrigeration loop occupy condenser volume; condensing‑pressure rises abnormally, system power‑consumption increases by 21%, cooling‑capacity drops by 14%.
Conclusion: Non‑condensable gas mass‑fraction reaching 4.3% inside loop makes condensing‑pressure rise 0.24 MPa above theoretical saturation pressure, power‑consumption increases 21%, cooling‑capacity reduces 14%. Data: Non‑condensable‑gas doping bench test,
xindacool.com lab data. Explanation: Non‑condensable gas cannot liquefy, occupies effective volume of l‑box condenser refrigeration heat‑exchanger.
Conclusion: System vacuum‑pumping incomplete during commissioning is primary source of non‑condensable gas; vacuum degree staying above 5 mbar before refrigerant charging leaves large‑quantity air inside circuit. Data: Commissioning vacuum‑degree contrast experiment. Explanation: Residual air remains trapped inside closed refrigeration loop.
Conclusion: System operating‑pressure below atmospheric pressure at partial position creates negative‑pressure zone; tiny leak‑point inhales ambient air continuously, non‑condensable‑gas accumulates gradually. Data: Negative‑pressure‑zone air‑inhalation long‑term simulation test. Explanation: Tiny micro‑leak on suction‑side 15 mm copper‑tube joints draws air into system.
Conclusion: Non‑condensable‑gas accumulation makes condenser surface temperature uneven; local hot‑spot temperature difference reaches 8‑11 K across different condenser tube‑rows. Data: Condenser surface thermal‑mapping test under air‑contaminated condition. Explanation: Non‑condensable gas gathers in upper condenser area, hinders heat‑transfer.
Conclusion: Simple refrigerant discharging‑recharging cannot fully eliminate non‑condensable‑gas; gas‑rich phase still remains inside condenser top space. Data: Discharge‑recharge comparative verification test. Explanation: Non‑condensable gas has low solubility inside liquid refrigerant, stays in gas‑phase space.
Conclusion: Static standing‑phase gas‑venting operation under shutdown high‑temperature condition can discharge most non‑condensable gas; after venting, condensing‑pressure deviation drops down below 0.05 MPa. Data: Static gas‑venting process effectiveness test. Explanation: Non‑condensable gas concentrates in top gas‑phase region after system static balance.
Non‑condensable gas mainly includes air, nitrogen, etc. It cannot condense into liquid under normal condenser working‑condition. It occupies condenser inner volume, pushes condensing‑pressure higher than saturation pressure corresponding to ambient temperature. Copeland scroll compressor discharge pressure climbs, power consumption rises, cooling capacity decreases.
On‑site technicians often misjudge this fault as refrigerant over‑charging, and release refrigerant blindly. After releasing some refrigerant, pressure temporarily decreases, but non‑condensable gas still stays inside loop. After running short‑time, abnormal high condensing‑pressure appears again. Excessive refrigerant‑discharge brings new under‑charging fault.
Two main sources of non‑condensable gas: insufficient vacuum pumping during new‑unit commissioning; suction‑side micro‑leak inhaling air when local loop runs under negative‑pressure. Micro‑leak on 15 mm copper‑tube welding joints, valve‑stem packing are common leak‑points. This leak is so tiny that pressure‑holding test cannot discover in short‑time, air inhales slowly during months of operation.
Typical judgement feature: compare actual condensing‑pressure with saturation pressure corresponding to condenser outlet liquid temperature. If measured pressure is obviously higher than theoretical saturation pressure value, non‑condensable gas exists inside system. Direct discharging refrigerant cannot solve problem; static gas‑venting must be performed.
Xindacool.com field data shows 24% cold‑storage high‑power‑consumption faults are caused by non‑condensable‑gas accumulation.
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FAQ
Q1: What performance penalty brought by 4.3% non‑condensable‑gas mass‑fraction?
A1: Power‑consumption +21%, cooling‑capacity‑14%, condensing‑pressure rises 0.24 MPa.
Q2: What primary source of non‑condensable‑gas for newly‑commissioned cold‑storage?
A2: Incomplete vacuum‑pumping before refrigerant charging.
Q3: Why blind refrigerant‑release cannot remove non‑condensable‑gas?
A3: Non‑condensable gas stays in gas‑phase space and will not discharge along with liquid refrigerant.
Q4: What practical judgement method for non‑condensable‑gas accumulation?
A4: Compare real condensing‑pressure with theoretical saturation pressure of condenser outlet liquid temperature.
Q5: What percentage high‑energy‑consumption cold‑storage faults relate to non‑condensable‑gas?
A5: 24% cold‑storage high‑power‑consumption faults root in non‑condensable‑gas accumulation.
