Preparation And Properties Of Composite Phase Change Materials For Cold Plate Radiation Cooling

The rapid growt.h of the global economy has led to an increase in energy consumption,with the construction industry accounting for an increasingly large share of energy consumption.The use of new functional building materials with thermal regulation capabilities,especially phase change energy storage materials,can better store and release energy in time and space,thereby improving the energy utilization efficiency of buildings.Incorporating phase change energy storage materials into radiant cooling panels can not only effectively regulate the surface temperature of the panels,but also reduce the energy consumption resulting from indoor temperature fluctuations,thereby increasing the duration of thermal comfort for occupants.Inorganic hydrated salt calcium chloride hexahydrate(CaCl2·6H2O)is a representative phase change material with high latent heat(190 J/g),easy availability,and suitable phase change temperature(29℃),and it is a research hotspot in the field of energy utilization.In this study,CaCl2·6H2O was used as the phase change energy storage base material to prepare a phase change cold storage panel that can be used in radiant cooling systems.Experimental tests and numerical simulations validated the feasibility of the phase change cold storage panel in practical applications,providing directions for exploring phase change radiant cooling.Firsts calcium chloride hexahydrate with a suitable phase change temperature was selected as the energy storage base material,and mannitol was used as the coolant,and carbon powder was used as the nucleating agent to prepare CaCl2·6H2O-mannitol phase change material suitable for cold plate radiant cooling systems.The content of mannitol was optimized through DSC and step cooling curve analysis,and the optimal content of carbon powder as an effective nucleating agent was screened.Subsequently,to address the issue of liquid phase leakages,CaCl2·6H2O-mannitol/SiO2 composite phase change material(CPCM)was prepared by melt blending method,using vapor phase silica(SiO2)as a porous carrier,and the shape stability and thermal reliability of the prepared CPCM composite phase change material were verified through BETS SEM,TG,FT-IR and other performance tests,indicating that it is suitable for radiant cooling systems.Next,CaCl2·H2O-mannitol/SiO2CPCM composite phase change material was integrated into an aluminum clip-in panel to prepare a phase change radiant panel.Two test chambers were constructed using the phase change panel and a regular aluminum clip-in panel,and the temperature distribution in the two test chambers was compared and analyzed.The experimental results showed that compared with the control group,the phase change group not only extended the cooling time,but also smoothed the indoor temperature fluctuations,ultimately achieving a total thermal comfort duration of 7.94 hours,an improvement of 73%in thermal comfort effectiveness compared to the control group,and an extension of 3.34 hours in thermal comfort duration,effectively reducing building energy consumption.Finally,FLUENT was used for simulation calculation and analysis of the internal heat transfer effect of the phase change cold storage panel during the cold storage and release stages,as well as the phase change rate of the phase change material.The simulation results showed that the prepared composite phase change material has good cold storage capacity,which can slow down the rate of indoor temperature rise and increase indoor thermal comfort.