Risk assessment of R22 air conditioners using R290.

Under the Montreal Protocol, Article 5 countries are proceeding with the phase-out of HCFC R22. One of the most prevalent uses of R22 is in split and window type air conditioners. Because R290 has similar saturated pressure-temperature characteristics and volumetric refrigerating capacity as R22, is miscible with the oils typically used in R22 compressors, is relatively cheap and is reported to yield favourable efficiency, it is often deemed as a desirable option to use in existing R22 systems. However, due to the concerns over charging a flammable refrigerant into systems that have been designed for non-flammable refrigerants, entities such as the Executive Committee of the Montreal Protocol and associated implementing agencies warn against such practices. This study addresses the flammability risk associated with applying R290 in converted R22 air conditioners and compares the risk against equivalent air conditioners that are specifically designed and built for R290. Different levels of conversion are considered in terms of the extent of modification that a technician may apply to the R22 air conditioner, ranging from no changes (“drop-in”) to comprehensive alterations in order to bring the equipment as close as possible in line with standardised design requirements.

根据《蒙特利尔议定书》（Montreal Protocol），第5条缔约方正逐步淘汰氢氯氟烃（HCFC）R22。R22最普遍的应用场景之一为分体式空调与窗式空调。由于R290的饱和温压特性、单位容积制冷量与R22相近，可与R22压缩机常用的润滑油互溶，成本相对较低且据报道能效表现优异，因此常被视为现有R22系统的理想替代工质。然而，由于担忧向原本设计用于非可燃制冷剂的系统中充注可燃制冷剂，《蒙特利尔议定书》执行委员会及相关实施机构等主体警告此类操作存在风险。本研究针对将R290应用于改造后的R22空调系统所引发的可燃风险展开分析，并将该风险与专门为R290设计制造的同类型空调进行对比。研究考量了技术人员对R22空调进行不同程度改造的场景，改造范围从无任何改动（即“直接充注”）到全面改造，以使设备尽可能符合标准化设计要求。