Investigation On Self-insulation Property And Microthermal Mechanism Of Phase Change Microcapsule Modified Mortar

In today’s world of huge energy consumption,buildings account for roughly half of the energy use.From low carbon energy saving to the present carbon neutral concept proposed,it is critical to do design and creating appropriate green construction materials or technology.Many energy-saving technologies have been created in recent years,both domestically and internationally,and the use of phase change materials in construction has increasingly gained popularity.To solve the problems of poor compatibility and detachment from the substrate in the application of phase change materials in construction materials,this thesis uses melamine-formaldehyde-urea wrapped with n-octadecane to produce phase change material microcapsules by in situ polymerisation.The addition of phase change microcapsules to cement mortar can improve the thermal storage capacity of cement,but the mechanical properties will be significantly reduced,therefore,equal amount of steel slag is introduced to replace part of cement to solve this problem.The finite element model of phase change microcapsule and phase change microcapsule modified mortar was constructed by COMSOL software,and its thermal insulation performance was analyzed and predicted.The coupling feedback between simulation and experiment was used to explain the heat conduction theoretically from the microscopic mechanism.Optical microscopy was used to observe the effects of the number of prepolymerization,reaction time,and solution speed on the initial morphology of the microcapsules;scanning electron microscopy,differential scanning calorimetry(DSC),and thermogravimetric analysis were used to analyze the microscopic morphology,thermal storage properties,and thermal stability of the phase change microcapsules.The findings demonstrate that the microcapsules made at a reaction speed of 500 rpm,the number of prepolymerization was 3 times,and a reaction time of 1.5 h have a nice morphology,are spherical in shape,and have a uniform particle size.The enthalpy of phase transition is also shown to be 177.8 J/g.Its structural and thermal management qualities were studied after equal volumes of steel slag powder were used in place of cement to create a steel slag cement mortar.The findings of the study indicate that the power of the steel slag cement mortar is generally inferior than the power of the purified cement mortar.The study demonstrates that the pure cement mortar’s power is typically higher than the slag cement mortar’s.As steel slag content and particle size grow,the distance between the cement mortar’s internal and external temperatures diminishes.The best performance combination is10 % steel slag in a 0.5 mm steel slag particle size.The results of the investigation into the impact of phase change microcapsules on the ability of slag cement mortar to regulate temperature revealed that the temperature discrepancy across both interior and exterior of the phase change slag cement mortar grew with increasing dosage.When the dosing is 15% and the difference between the inner and outer surface temperature is the highest at various heating temperatures,the mechanical strength of the mortar is lower than that of pure cement mortar.However,the mechanical properties are not significantly impacted by the equivalent replacement of steel slag.The phase change process of phase change microcapsules affected by external environment was simulated by COMSOL software,and it was found that the liquid content inside the core material gradually increased and the solid content gradually decreased when the external temperature approached the phase change temperature;Then,the thermal insulation effects of phase change mortar and pure cement mortar at different temperatures were simulated and analyzed,and it was found that the inner surface temperature of phase change mortar decreased by 0.3 ℃,0.9 ℃ and 1.6 ℃respectively compared with that of pure cement mortar.