| In recent years, a huge consumption of electricity of air-conditioned in modern building account for the total electricity consumption in buildings by 50%. Air conditioning is not only a great power, and the peak hours of cooling load match the peak period of electricity in the city, which exacerbated the imbalance of peak power shortage and the contradictions of the lack of electricity, so thermal storage air conditioning systems can better solve this problem. In order to meet domestic requirements on storage air-conditioning, so small-scale ice-storage air conditioning system came into being, but ice charging and discharging of the small-scale ice-storage air conditioning system is in the research stage at home and abroad, therefore, this paper will use the mathematical model to further study on characteristics of the thermal storage of small-scale ice-storage air-conditioning system.In ice storage process, the inside and outside of ice-on-coil exist complex phase-change process, namely, the phase-change process of vaporization and the phase-change process of solidification, this paper only consider the phase change process of solidification on the tube outside.This paper will reserch a tube sections and section of pipe sections in a storage tank, and set up the mathematical model of direct evaporation coil freezing process, and use FLUENT simulation software to simulate the six groups working conditions of different evaporation temperature and different initial fluild temperature with two-dimensional numerical simulation. For the specific characteristics of the study objects, I determine the step size of grid for the 1mm after repeated accounting,then simulate straight pipe sections and the cross-section of pipe sections which exist ice water two-phase states,which use the VOF model of multiphase flow model and interface tracking method.The numerical simulation begins after the mathematical model builted , under the guidance of this numerical model, the simulation compltetes the storage process which has the design cycle of ice storage for 3h, and simulates the six conditions of the storage process ,which is the evaporation temperature of -5℃, -10℃, -15℃and initial temperature of 10℃and 15℃, and simulates the temperature distribution inside the ice storage tank, ice thickness outside the ice-on-coil, the rate of ice storage and the quantity of ice storage with the changes of ice storage time .Through the analysis of simulation results, we know the ice-melting characteristics of the outside of ice-on-coil ice storage system, namely, the thermal storage process can be roughly divided into three phase which is sensible heat express ice storage phase, latent heat express ice storage stage and the latent heat slow ice storage phase.The ice storage capacity is on behalf of the sum of sensible heat ice storage and latent heat ice storage, which can know the variation characteristics of the entire ice storage process.It shows that the ice storage capacity has the fastest-growing stage about the former 1/5 period and the latter growth trend has gradually slowed down; evaporation temperature of refrigerant influence the entire process of ice storage and the curvature which change with time of ice storage capacity is different with the different of the evaporation temperature; the initial fluild temperature has less influence to ice storage capacity, which mainly exist in the process of sensible heat ice storage stage.Finally, the results of numerical simulation compare with the results of experimental, which shows that numerical simulation have the better response to the experimental situation, and further verifys the reliability of numerical simulation, and this paper select the best ice storage parameter.
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