To overcome the ozone layer depletion problem, the Indonesian government has ratified the Montreal protocol and its amendments. The import of R-12 refrigerant to Indonesia has been banned since the end of 1997. Meanwhile, most of Indonesian milk cooling units use R-12. Therefore, it is expected that these cooling units have to be switched to other refrigerant soon. Almost all of Indonesian milk cooling units belong to small or medium dairy cooperatives that cannot aflord to retroï¬t their systems to R-134a. In this research, a milk-cooling unit designed for R-12 was directly switched to propane/butane refrigerants (propane-isobutane, and propane/n-butane refrigerants) without any modiï¬cation. The performances of the milk-cooling unit operated with propane/isobutane, propane/n-butane and R-12 geï¬igerants were investigated. It was found that propane/n~bntane refligerant is the most eflicient, and followed by propane/isobutane and R-12. Results of several other milk cooling units were also reported.
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