Study On The Dynamic Ice Storage Unit With Double Evaporator

Rapid economic growth in china has led to a sharp increase in annual electricitydemand, so power supply and demand situation will be still tense. By using demandside management, ice storage technology can achieve peak load leveling, which is oneimportant way to ease the contradiction between electric power construction and newelectricity demand. Ice storage technology can reduce the capacity of refrigeration unitand the running cost of air conditioning system. Therefore, ice storage technology hasbeen more widely used in our country.On the basis of the traditional single-evaporator dynamic ice storage unit, adynamic ice storage unit with double evaporator has been proposed. The main feature ofthe system is that ice-making condition and chilled water condition use differentevaporator. The honeycomb plate evaporator and the falling film evaporator wererespectively used in the ice-making condition and the chilled water condition, whichmay improve the coefficient of performance of the unit. The unit can make the best useof valley-load electric power to storage ice at night. When cool thermal storage loadcan’t meet air-conditioning cooing load, the unit efficiently runs the mode of chilledwater condition, which can take the economic advantages of ice storage air conditioningsystem and will not bring about excessive capacity. At the same time, the main featuresof the system components and the process of selection and design were introduced.A multi-function performance test-bed that can test the performances of dynamicice storage units and chillers has been designed on the basis of GB/T10870-2001, GB/T26194-2010and other relevant standards. The overall design scheme of the test-bed wasproposed. The unit adopted the means of liquid secondary refrigerant and the heatbalance as the testing methods of the test-bed. When testing the condition of chilledwater, the method of water blending in the pipeline was applied. The unit has a simplestructure and has the characteristic of energy saving, which can quickly reach thedesired testing conditions. The design calculation of the test-bed was concretelyexpounded. The test-bed with measurement and control system of high accuracy canmeet the requirements of the relevant performance testing standards, and theexperimental results of the double evaporator ice storage system have achieved thetarget of unit designed, which showed that under the chilled water and ice-makingconditions the unit had excellent performance. By means of the phase change heat transfer theory, heat transfer analysis andice-making optimization of the dynamic ice storage unit with dual evaporator had beencarried out. One-dimensional phase change model was utilized to approximatelyanalysis the process of ice-making. The relations between ice thickness, ice-makingvelocity and time at different inlet temperature of chilled water for ice-making wereinvestigated. Based on the heat transfer theoretical analysis, a calculation method of theoptimum ice-making time was programmed and in theory the optimum ice-makingtimes at different inlet temperatures of ice-making chilled water were given.