Research On Simplified Model Of Energy Consumption Calculation Of Double Skin Facade

The double skin facade(DSF)is an improved form of the traditional single skin fagade and is widely used in modern buildings.However,the heat transfer mechanism of the double skin facade is complicated,and the existing research methods generally have problems such as excessive theoreticality and slow calculation speed,which are difficult to meet the needs of actual engineering calculations.This paper proposes a new method that uses CFD simulation technology and an improved lumped model to establish the room heat gain of the DSF.An experimental device of the DSF was designed and built to study the thermal and energy consumption performance of the DSF.The experimental data validate the method and showed that the method can be used in the design of DSF.The main contents are as follows:(1)The heat transfer of the DSF was experimentally studied under the condition of no solar radiation,and the relevant factors affecting the thermal insulation performance were explored through a small scale DSF system.The experimental results show that cavity ventilation,the temperature differences between indoor and outdoor,seasonal patterns and cavity depth all have a significant effect on the heat transfer process of DSF.And there is an optimal cavity depth to achieve the best insulation performance.The comprehensive heat transfer coefficient obtained in the experimental study can also be used in the subsequent study of DSF under solar radiation.(2)The Fluent software was used to establish the CFD model of the DSF without solar radiation,and the model was validated by the above experimental data.The CFD model was then used to study the performance of the full-scale DSF.The effects of cavity depth,facade height,temperature difference,and seasonal patterns on the thermal insulation performance of the DSF without solar radiation were analyzed.The simulation results show that the optimal cavity depth of the facade is related to the size of the cavity openings.(3)Based on an improved lumped method,the heat transfer model of DSF was established.The model simplifies the outer skin and the ventilated cavity as part of the external environment.Then the numerical relationship between the cavity heat transfer coefficient and solar radiation was established,which simplifies the heat transfer calculation while ensuring the accuracy.The model is suitable for evaluating the energy consumption of the DSF at design stage.At the same time,an experimental device of DSF with a size of 1.3m × 1.1m ×0.88m was built,and the accuracy of the model was verified by the measured data.On the basis of experimental and simulation studies,the relationship between room heat gain and solar radiation,inner skin temperature and indoor air temperature is discussed.Then a linear formula for calculating room heat gain is obtained by fitting the experimental data.(4)A CFD model of natural ventilation DSF with solar radiation is proposed,and the heat transfer coefficient in the cavity is obtained by CFD method.Combined with the dynamic heat transfer model described above,this paper establishes the energy consumption estimation method of the DSF in design stage.The main processes include:input boundary parameters,use CFD model and dynamic heat transfer model to predict the temperature of the inner skin and indoor air temperature,use the linear formula to calculate the hourly room heat gain.In this paper,the heat transfer process of the DSF is studied through experiments and CFD methods.Then an energy consumption calculation method of DSF is established.This method combines the accuracy of the CFD technology and the simple and fast of the lumped method,which can not only meet the needs of engineering accuracy,but also simplify the calculation process and facilitate the engineering staff to master.It is suitable for the design stage of DSF.