Simulation Optimization And Experimental Study On Performance Of Two-stage Phase Change Heat Storage Heating System

At present,our country’s urban heating system is constantly improving,and the phase change heat storage heating system with phase-changing heat storage device is also an attempt in recent years.The phase change heat storage device uses the phase change characteristics of its internal phase change material to change the time and space distribution of energy,with the peak valley electricity price policy to achieve the purpose of"peak-filled",and achieve the increase in heating system.The phase-changing heat storage heating system is still largely improved in a low-conducting coefficient of the phase change material.According to the basis of step phase change heat storage,the development potential of two-stage phase change heat storage heating system is explored through numerical simulation and experimental studies.This paper uses the Fluent software to establish a two-dimensional model of the two-stage series phase-in-storage device and determine the optimal series.Take the degree of simultaneous synchronous factor,multi-stage average thermal energy transfer efficiency and accumulation heat ratio as evaluation indicators,analysis of phase change temperature,phase change latent heat,thermal conductivity ratio of two-stage phase change heat storage device performance The influence,thereby determining the significance and optimal combination of each influencing factors using three-factor-four-level orthogonal analysis.The results showed that the second stage phase change temperature 59°C,phase change latent heat 250 k J/kg,the two-stage thermally conductive coefficient ratio of 1 has the best integrated performance.According to the results of the numerical simulation,the two-stage phase change heat storage heating system test bench is set,and the thermal performance of the device and the thermal performance of the system are performed.First,the performance of the two-stage series apparatus and parallel devices under the same conditions is compared with the indicator,the release heat and the accumulation heat ratio.Second,the change law of the performance of the two-stage series phase change heat storage devices under different conditions by changing the inlet temperature,initial temperature and flow of the device.The experimental results show that the heat storage capacity of the two-stage series of secondary series devices in the PCM_70°C/PCM_59°C can be increased by 53%compared to the PCM_70°C/PCM_70°Csingle-stage parallel device,and the amount of release heat can be increased by 66%,the maximum ratio of heat storage and release heat can be increased by 16%.Increasing the water temperature and flow rate can increase the heat accumulation of the two-stage phase change heat storage device,increasing the flow rate can increase its release heat,and increase the initial temperature to the release heat increase is not obvious.Finally,in the experiment of the phase change heat storage heating system,the load change changes in the load simulation water tank are achieved with the difference between the heating temperature standard and the effective heating,and the electric boiler is combined with the two-stage phase change heat storage device.Test the heating performance of two-stage phase change heat storage heating system within24 hours within a different heat load.The results show that the effective heating time of the two-stage phase change heat storage device under low heat load can reach 1.47,and the heat storage temperature and flow rate are used to increase the heat storage temperature and the flow rate of the heat storage stage,which can make the effective heating time long coefficient from 0.58 to 0.9,the heating of the electric boiler can meet the heating demand.