Research On Self-responsive Phase Change Energy Storage Water Tank Based On University Cassette Bath Residual Heat Recovery Cascade Utilization System

Energy is the material basis for the survival of human society and the continuous development and progress of society.Based on the characteristics of the university bath system,this article analyzes the PCM screening,the structure and operation of phase change energy storage water tanks,The self-response control system is proposed,and the test of the heat storage and release capacity of the phase-change energy storage tank is set up.First,the PCM was screened based on the selection principles of phase transition temperature range,phase transition latent heat value,subcooling,chemical performance,and economic performance.It was determined that paraffin-based phase change materials were selected as the phase change energy storage tank’s PCM.The step cooling curve method was used to analyze the phenomenon of subcooling and phase separation.The test results show that the final determination of paraffin A as PCM has a phase transition temperature range of 41.4 to 43.5 ° C,a peak of 45 ° C,and a latent heat of phase transition of 175.9J / g.There is no obvious undercooling and phase separation.Secondly,a phase change heat transfer enthalpy method model and a solidification / melting model were established,and the FLUENT numerical simulation software was used to analyze the phase change energy storage conditions.The simulation results show that the phase change unit tube diameter of 30 mm is more conducive to the heat storage and release of the PCM.Increasing the heat storage temperature can reduce the completion time of the phase change energy storage water tank.The flow rate will affect the PCM solidification rate and heat release capacity in the phase change unit.Finally,based on the Siemens S7-200 PLC controller,a self-response temperature control system was proposed,The test results show that the hot water outlet of the phase change energy storage tank to drop to 40 ° C,the more heat is emitted,and the greater the heat release capacity.;When the make-up water temperature is 15 ℃ and the make-up water flow rate is 0.2m3 / h,the heat storage capacity of the phase change energy storage water tank is increased by 27%;as the phase change unit volume ratio in the phase change energy storage water tank increases,the phase change unit volume is fitted.The functional relationship between the ratio and the time when the outlet temperature of the PCM hot water is not added is as follows,where the correlation coefficient is R2 = 0.9672,and the correlation coefficient is close to 1,confirming that the phase change energy storage water tank can release more hot water than the traditional water tank,The stronger the heat storage capacity and the larger the phase change unit volume ratio,the more heat can be provided,providing a certain reference for the application of phase change energy storage water tanks in college baths.