High capacity mechanical water-vapor compression vacuum ice machines for district cooling and heating

The theoretical advantages of the refrigeration cycle using the vacuum ice cooling process based on a water vapor refrigerant cycle are well known and have already been demonstrated in various small scale applications. The advantages include: low energy consumption, reduced capital investment in heat exchangers and coolant piping systems, and lower overall operating and maintenance costs. However, the commercial development of large scale water vapor refrigerant systems for the production of pumpable ice slurries have heretofore been hampered by the limitations of the available compressor technology and by problems associated with the transportability of ice slurries. These factors led to the development and installation of a 3 MW(ref) vacuum ice machine in South Africa - the first of its kind - for application in the cooling of deep level gold mines. The process developed uses direct contact heat transfer in evaporation and condensation with water vapor as the sole refrigerant. The system employs a unique two stage centrifugal compressor system designed and developed specifically for large flow rates and high compression ratios. The vacuum compressor technology is an extension of existing technology based on the results of thirty years of development evolution in commercial seawater desalination systems. The present papermore » describes the technical characteristics of the machine recently developed for the above application and the equipment used to produce and transport concentrated ice slurries. The commercial use of the water vapor compression cycle for cooling or heating systems and for various potential industrial applications are described as well.« less