Study On Application Of Phase Change Microcapsule In Solar Composite Air Conditioning System

The global energy structure is in the period of optimization and transformation in recent years,and the development of renewable energy such as solar energy is rapid.Although the energy supply and consumption pattern dominated by coal will not change in a short period of time,with the growth of renewable energy consumption increasing year by year,the development and utilization of solar driven composite air conditioning system can reduce the use of conventional energy effectively as well as carbon emissions.Because of the intermittent and dispersive characteristics of solar energy,the energy utilization rate of the existing solar composite air conditioning system is generally low,which can not fully reflect the advantages of the solar composite air conditioning system.Therefore,in order to improve the energy utilization rate of solar energy composite air conditioning system,on the basis of literature and data research,a solar energy composite air conditioning system with cold storage based on phase change microcapsules is put forward in this paper.Firstly,the thermodynamic analysis of the system is carried out based on the refrigeration cycle of the system,and the calculation model is established.Based on the generator temperature and evaporator temperature,three different mass fractions of phase change microcapsule suspensions,5wt.%,10 wt.% and 15 wt.%,were selected respectively.The physical properties of the suspensions are analyzed and the main physical parameters of the suspensions are calculated.Secondly,heat transfer characteristics of the cold storage device is analyzed,and the simulation of the cold storage device is built by Fluent according to different mass fraction,different evaporation temperature and different media.The results show that due to the influence of physical properties on natural convection,the cold storage capacity decreases with the increase of mass concentration before the start of phase change.When the phase change temperature is reached,the temperature of the suspension with large mass concentration decreases faster,and the overall cold storage performance is betterthan that of the suspension with low mass concentration.Moreover,the higher evaporation temperature is not conducive to the formation of natural convection,and the same cold storage capacity needs longer cold storage time.Compared with ice storage,under the same evaporation temperature,compared with phase change storage,with the formation of ice storage layer,the blocking effect on heat transfer is strengthened.The distribution will be more uneven,and the increasing rate of the storage capacity gradually lags behind the phase change storage.Lastly,the exergy analysis model of whole process is came forward,and the whole process of a building in Zhengzhou area in typical day conditions is analyzed.MATLAB is used to optimize the operation scheme of cold storage and cooling release.The results show that: the use of cold storage device can improve the overall performance coefficient of the system,and the phase-change cold storage has the highest exergy efficiency,reducing the consumption of primary energy;during the whole cooling season,the optimization scheme with the least power consumption can save more than 300 RMB,and the optimization scheme with the least power consumption can save more than200kW·h of electricity.To some extent,the optimization of the distribution of cooling release capacity improves the efficiency of the whole process and the utilization rate of primary energy.It provides data support for the operation control strategy of the energy storage solar composite air conditioning system with phase change microcapsules.A new type of phase change material is selected as the cold storage working medium of the solar energy composite air conditioning system in this paper,and a solar composite air conditioning system with cold storage based on phase change microcapsules is constructed.On this basis,combined with the characteristics of phase change material energy storage,and the analysis of the whole process of the system,the operation control strategy of the solar composite air conditioning system with cold storage is optimized,which provides theoretical support for the popularization and application of solar composite air conditioning.