The difference in heat transfer between foam concrete insulation board and organic foam insulation board:
(1) Radiation heat transfer. As far as radiant heat transfer is concerned, it is only related to the temperature difference and the structure and characteristics of the material, and the structure and features of the article mainly refer to the transmission and reflection performance of heat radiation, which is also related to the color depth and surface state of the content. The color of the foam concrete insulation board is darker than that of the organic foam board. Microscopically, the former is more comfortable to crystallize than the latter, and the surface roughness must be lower than the latter. It is difficult to judge the level of heat transfer capacity of the two heat radiation.
(2) Conduction heat transfer. As far as conduction heat transfer is concerned, it is only related to the temperature difference and the nature of the material. As far as the quality of the content is concerned, the constituent elements of foamed concrete are Si, 0, Ca, H and some other metal elements, all of which exist in compound form, There are no free electrons that can quickly transfer heat; the constituent parts of organic foam insulation boards are C, H, and N. These elements also exist in the form of compounds, and there is no free electron that can quickly transfer heat. The difference lies in the chemical bond. Different, it can be seen that the heat conducted by the two thermal insulation materials is intensified by the vibration of heated atoms and transferred through chemical bonds. Ordinarily, to receive the same energy, the vibration amplitude of a large-mass particle is generally smaller than that of a small-mass grain. In this sense, the thermal conductivity of the foam concrete insulation board should be lower than that of the organic foam board.
(3) Convection heat transfer. In terms of convective heat transfer, if the medium in the hole is air, the air convective heat transfer is only related to the temperature difference and the hole size of the material. Generally speaking, the pores of the foam concrete insulation board are much larger than the organic foam insulation board. It is not difficult to find when the same temperature difference is added to the foam concrete insulation board. The natural foam insulation board of the same thickness, the temperature difference carried by a single hole of the foam concrete insulation board and the natural foam insulation board is different, that is, the former is much larger than the latter. As a result, the convective heat transfer capacity of the old is much higher than that of the second.
(4) Phase change heat transfer. In terms of phase change heat transfer, the foam concrete slab contains a certain amount of free water, some easily lost crystal water or adsorbed water, which may cause phase change heat transfer of moisture during testing and use; organic foam insulation The board has a robust hydrophobic effect, so there is no phase change heat transfer problem of humidity, but the foaming agent and flame retardant used in its production often contain volatile components and cause phase change heat transfer. Since the heat of vaporization of water is higher than that of ordinary low-boiling organics, and the volatile components in the organic foam insulation board will become less and less over time, the phase change heat transfer capacity of the foam concrete insulation board must be higher than natural foam insulation board.
From the above analysis, it can be seen that in terms of radiation and conduction heat transfer, there is no significant difference between the foam concrete insulation board and the organic foam insulation board. Still, in terms of convection and phase change heat transfer, the former is significantly higher than the latter or Said heat resistance performance is significantly inferior to the latter. In the field of building exterior wall insulation, to truly realize the replacement of organic foam insulation boards by foam concrete insulation boards, it is necessary to research the structure and composition of foam concrete to reduce its thermal conductivity effectively.
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