With the rapid growth of China's economic level, the continuous improvement of industrialization level, and the accelerating urbanization process, it is estimated that by 2020, China's high energy-consuming building area will reach 70 billion m2, and the annual building energy consumption will reach 410 million tons. Standard coal and 1.2 trillion kWh. The use of energy-saving and environmentally-friendly new building materials to strengthen the thermal insulation performance of building envelopes is an essential way of producing energy conservation.
Phase change energy storage technology is a method of energy storage by utilizing phase change materials (PCM material) to absorb or release a large amount of latent heat of phase change during phase change. The ambient temperature remains relatively stable during energy storage, which is ideal.
Phase change energy storage concrete combining phase change technology and foam concrete is a new type of foam concrete made of concrete material and incorporating phase change material in the practical preparation process. As the wall and roofing material in the building envelope structure, it can better maintain the indoor temperature stability, improve the indoor thermal comfort, and reduce the energy consumed by the use of temperature control equipment such as air conditioners and heating in the room: energy saving and environmental protection.
At present, most of the applications in the concrete foam field are solid-liquid phase change materials. During the phase change process, the solid-liquid phase change material will be converted from a solid-state to a liquid state, and it will flow directly in the building. To maintain a stable state, it will not flow to the outside during use. Usually, some carriers are used to absorb and accommodate the PCM material, and a phase change energy storage building material having a stable shape and having heat storage and discharge capability is prepared. There are several ways to combine PCM metal and foam concrete:
(1) Impregnation method
The impregnation method is to directly soak the foam concrete in the liquid phase change material and adsorb the phase change material in the pore by the capillary adsorption force of the foam concrete pore. This method has low cost, convenient operation, low requirements on the experimental environment, and is suitable for on-site supervision.
(2) Direct addition method
Direct addition means that the phase change material is directly added to the raw material of foam concrete as a component of the building material in the preparation stage of foam concrete. The method is simple in operation, low in cost, and the phase change material can be uniformly distributed in the building material. The amount of the phase change material can be controlled.
(3) Porous material adsorption method
The porous material adsorption method is similar to the principle of the impregnation method. It refers to a porous material having a high porosity and a large specific surface area as a carrier, and a PCM phase change material is sucked into the micropores of the porous material to form a composite phase change material. The finished content can be added to the foam concrete as aggregate to create a phase change energy storage building material with heat storage and release capability. Commonly used porous materials are expanded perlite, diatomaceous earth, ceramic sand, activated carbon, and expanded graphene. The porous material plays a supporting role in the phase change material in the phase change process. It can effectively reduce the leakage of the phase change material into a liquid state so that the composite phase change material can maintain the solid shape and the whole phase change process. It's performance.
(4) Microcapsule method
The microcapsule method is to coat the phase change materials with a stable polymer film and seal it in a microcapsule formed by a polymer film to build a solid particle having a core-shell structure. The microcapsule method not only solves the volume change and liquid phase leakage of the solid-liquid phase change material products during the phase change process but also improves the heat transfer efficiency of the phase change material products, mainly eliminating the phase change materials in the phase change. The phenomenon of supercooling and phase separation in the process also avoids the direct contact of phase change materials with the external environment, reduces the volatilization toxicity of some phase change materials, improves the durability of phase change energy storage building materials, and prolongs the construction.