Simulation Study Of Heat Transfer Characteristic Of Double Skin Facades

Doub1e skin facades can bring beautiful architecture outline ,comfortable indoor environment and good effect of energy saving. Nevertheless,the design of double skin facades is a comp1icated job which needs to consider many factors synthetically. If only we know its heat transfer characteristic,we can correctly design a system of double skin facades meeting the local climate well. Because of the variety and complexity of its effect factors,the domestic study of doub1e skin facades is still at the stage of start. The reference documents about it are not enough so that double skin fades are not widely used in our country. So it is necessary to know its heat transfer characteristic wel1 by study,then we can provider reference to engineering designers and evidence for the establishment of the criterion concerned.Based on the research projects supported by the Hunan Natural Science Fund(NO.08JJ3093),this paper adopts the method of nodal network simulation and computational fluid dynamics(CFD) simulation to study the single storey double skin facade and its heat transfer characteristic. And the thesis consists of the following contents:1. The thermal network model of an external respiration double skin facade building in Changsha is established to analysis the influences of glass type and airspace width for its heat transfer characteristic by Window6.2 software.The major results are detailed as follows: the effects of glass type and airspace width on heat transfer characteristic are very remarkable. To choose the glass type for purpose of improving the heat transfer characteristic and adding to the beauty of the architecture outline. To increase the airspace width can improve its thermal performance. The width about 500mm is the best project in the hot summer and cold winter area in China. In that design, the double skin facade can not only improve the heat transfer characteristic, but also economize building area.2. FLUENT is used to study the characteristic according to the CFD theory in this paper. RNG k-εand P1 model is used to simulate the air flow and solar radiation in the system of double skin facades ,and comparative research of experiment and simulate is also done.The major results are detailed as follows: the CFD results are validated against experiment data from the foreign literature and very good agreement between the prediction and measurement is achieved. The temperature and velocity fields are calculated to unveil there is a recirculation zone of the outlet and the corner. This recirculation zone has a high temperature because absorption of solar radiation heat for quite a long time. We must avoid this phenomenon when designing.3. The comparative research of two simulation method is done.The major results are detailed as follows: these two methods have the advantage of high goodness of fit and satisfactory effect. These two simulation methods are worth learning each other. The method of combining two or three methods is more and more mature, and it is worth popularizing in engineering practice.4.According to the study,a system of double skin facades which is suitable to use in the hot summer and cold winter area is designed. When planning optimum design of the double skin facade, the main factors considered by the designer are as follows: the airspace width, glass type, sun shade design, ventilating form choice and operation strategy. To consider all these factors for purpose of building energy saving.The method of nodal network simulation and computational fluid dynamics simulation are adopted to design a best energy saving effect with stage of double skin facade planning and design.