The Preparation Of Phase Change Microcapsules And Its Application Of Phase Change Thermal Storage Performance In Building Materials

In recent years, with the increase of building energy consumption, the researchers increased the research on the phase change energy storage technology in the field of building energy conservation. A large number of phase change material is introduced into the building energy-saving materials to achieve the energy saving effect. But so far phase change material can't still perfectly achieve the effect of conctrolling the ambient temperature. They have some faults such as the phenomenon of cold , poor stability and corrosive to the skeleton structure, and more importantly, the narrow temperature range of the phase transition temperature can not be good for effective regulation for the environment with a large range of temperature.Therefore, the subject adopts paraffin which has some advantages such as high latent heat, low vapor pressure when melting, chemical stability, and almost has no supercooling phenomenon, phase separation and corrosion as phase change materials. Paraffin is packed into the microcapsules, and separated with the reinforcing material to assure to the skeleton material, which can make paraffin maintain the solid state during phase change. In this issue, phase change microcapsules can be made by emulsification technology with paraffin as a core material, urea-formaldehyde resin as wall. DTA curves of Microcapsules are measured, and latent heat of the phase change material can be obtained and the stability can be proved after the repeating phase transition. The microcapsules obtained will be added to the cement paste matrix, obtained by storage temperature materials, and DTA curves of phase change materials in the building can be measured and their latent heat and repeating stability can be obtained after phase change. In software simulation, FLUENT is flow calculation software which is a widely used and more accurate, Using this software, its environment built with the phase change material can be simulated, which can be compared intuitively with the experimental results.Under the understanding of the phase transitions, heat transfer and FLUENT software, the effect of phase change material controlling the temperature of the environment can be observed and simulated. Origin7.5 image processing software can be used to sort, fit, analyze the experimental data, and the characterization of phase change materials can be gotten to express the effect of controlling a certain environmental temperature, which confirms that phase change materials can play an effective role in building energy efficiency. The study on the content and major achievements of this article is as follows:(1)Through experiments, it is found that mixing speed, temperature and the amount of paraffin have an impact on micro-capsule size, appearance during synthesis. When the speed is 450rmin, paraffin amount used is 280g, and the temperature is 63~65℃, the appearance of micro-capsule is smooth, and the distribution of particle size is uniform.(2)Through experiments, the stability of phase change microcapsules has been studied. In experiments, it's found that micro-capsule is stabile in alkaline environments, and is easily damaged in the acidic environment; it's also found that the stability of micro-encapsulation is good under thermal cycling.(3)Differential Thermal Analysis method will be applied on the phase change Micro-capsule and the cement cylinder containing Microcapsule. It is found that temperature-control capability of phase change cement material is several times to a dozen times more than that of the normal cement material.(4)In the experiment, with the amount of micro-capsule increasing, micro-capsule has better ability of controlling the rise of temperature, and the heating rate and the cooling rate is lower. Then the adiabatic temperature rise of concrete containing Microcapsule has been tested, and it's found that phase change microcapsules can effectively reduce the hydration temperature rise of concrete.(5)Temperature control effectiveness of floor slab with different contents of micro-capsule simulated with CFD software, and it's found that micro-capsule can effectively reduce fluctuations of temperature inside wall board; and then under the situation on different dosage of micro-capsule and different phase variable temperature, controlled temperature effect of phase variable micro-capsule on hydration temperature rise of large volume concrete has been simulated, and it's found that micro-capsule whose phase change temperature is low can have more effective of controlling the rise of temperature.