Study On Thermal Insulation And Insulation Performance Of Horizontal Closed Cavity Of Phosphogypsum Cavity Mould Beamless Floor

The heat exchange between buildings and the external environment is mainly realized through the building envelope structure.Therefore,improving the thermal insulation performance of the building envelope structure and reducing the energy consumption of buildings have important practical significance for the realization of national energy saving and emission reduction goals.As a new type of building floor structure,phosphogypsum cavity formwork beamless floor has both the function of building envelope structure and its own thermal insulation performance has a greater impact on the energy consumption of buildings.Phosphogypsum cavity formwork beamless floor is mainly composed of concrete rib beam,concrete slab and phosphogypsum cavity.The thermal conductivity of concrete material is larger,and the shape is relatively fixed,so the heat transfer performance is difficult to change.The thermal conductivity of phosphogypsum cavity material is lower,and there is air layer in the middle.Reasonable optimization will make the thermal insulation performance of phosphogypsum cavity obtain.Raise.Therefore,in order to improve the thermal insulation performance of the phosphogypsum cavity mould beam-less floor,we should start with the phosphogypsum cavity.In this paper,phosphogypsum cavity as the main research object,its thermal insulation performance was studied.The main research contents and results are as follows:(1)The heat transfer of the phosphogypsum cavity is a coupled heat transfer process in which three heat transfer modes coexist.By analyzing how to reduce the heat transfer of the three heat transfer modes to reduce the total heat transfer,it is considered that changing the convective heat transfer ratio changes the heatconduction and radiation heat transfer.More reasonable;among the many factors affecting the thermal insulation effect of the air layer,reducing the thickness of the air layer is the most reasonable way to improve the thermal insulation effect of the cavity.(2)The thermal conductivity of phosphogypsum was measured by the thermal conductivity tester;the thermal conductivity of the main parts of the phosphogypsum cavity was measured by the thermal insulation performance testing device of building envelope and the multi-channel temperature and heat flow tester;the air layer was separated by corrugated paper,which proved that changing the thickness of the air layer could change the heat transfer of the phosphogypsum cavity,thereby changing its heat transfer coefficient.(3)Using FLUENT finite element software,the steady-state heat transfer process of the phosphogypsum cavity under the experimental condition is simulated,and the heat transfer coefficient of the phosphogypsum cavity under the steady-state heat transfer state is obtained.The air flow velocity in the phosphogypsum cavity under the thermal insulation state is faster,and the Grashov number Gr in the air layer is much larger than the criterion for the change of heat transfer law.The air flow in the air layer is turbulent.(4)The thermal resistance of the non-beam floor of the phosphogypsum cavity mold is much larger than that of the ordinary reinforced concrete floor slab.The use of a phosphogypsum cavity mold without a beam cover requires a small amount of insulation measures.Can meet the specification requirements.(5)The simplified model of phosphogypsum cavity is used to change the inner air layer thickness,and the optimum air layer thickness is obtained by numerical simulation.A double-air-layer phosphogypsum cavity was designed,and its heat preservation performance was improved,and its fabrication was simple,the weight increased less,and the construction difficulty was not increased.