SEMI HERMETIC AND HERMETIC AMMONIA COMPRESSOR PACKAGES

摘要

Not only environmental concerns that make ammonia, one of the oldest refrigerants in industrial use so attractive among old and new users, its excellent thermal properties also enables design and installation of systems with high COPs as compared to HFCs. The main disadvantage of ammonia, however, is toxicity, smell and flammability. For this reason, most ammonia refrigeration systems are of indirect type using secondary refrigerants. There is, therefore, a need for systems with reduced refrigerant charge in order to increase safety and reliability of ammonia refrigeration systems. Miscible oil, compact heat exchangers, electronic expansion valves and semi hermetic compressors have been developed and as a result systems with drastically reduced refrigerant charge have been introduced into the market. This paper reports on the development of semi hermetic ammonia compressor packages coupled with interior permanent magnet motors.