The present invention belongs to the field of air conditioning and refrigerating technology and is used for providing cold source for central air conditioning system. Technologically, the present invention features that under the high-vacuum environment produced by centrifugal force of the impeller rotating at high speed, the cooling water sprayed from the spraying nozzles is evaporated at low temperature and cooled with the vapor being exhausted by the impeller to atmosphere while the cooled water being used as cold source for the central air conditioning system. The wedged rings are used for raising the efficiency of the impeller in producing vacuum. The present invention may be used alone or parallelly. |