Applied Research Of Multistage Energy Storage Refrigeration System On Cold Storage

An introduction dealing with the refrigeration method and the working flow of multistage energy storage system using NH3-H2O as working fluid is presented, which is mainly applied in the industrial and commercial energy storage refrigeration system. The principle of the system states that the off-peak electricity is transformed into the refrigerating potential of aqueous ammonia, and stored in solution storage tank. The stored potential can be transformed into cold energy by means of gradual evaporation or absorption, when needing one or multistage cold energy. The system can be utilized to shift electricity load from on peak periods to off peak periods, and has many advantages such as large energy conversion efficiency, low cost, flexible operating mode, simple storage equipment, and multistage range temperature, which make it especially applicable in multistage cold storage or industrial cooling.Based on the computation of ammonia-water thermodynamic properties and the dynamic models of the system working process, the energy transformation and storage dynamic processes according to a typical two-stage cold storage located near by Yangzi River are numerically simulated under the full storage strategy. The regulations or relationships between the main working parameters during the energy charging or discharging time, and the load capacity and variation characteristics of the devices, are obtained by simulation. All these results are useful for understanding of operation characteristics, design or selection of the devices, and also helpful for designing the dynamic control program of the multistage energy storage refrigeration system.In this paper, the influences of reheater on COP, the relations between the increment of solution concentration and COP or storage density, the influences of inlet cooling water temperature and relative cooling load on the parameters of working solution charged into the system and on COP of the system are also discussed. These conclusions provide some theoretical references for the deep research of the multistage energy storage refrigeration system.