Research On Optimization Of Heat Transfer Of Envelope Structure Under Solar Radiation

Solar radiation is the main heat source that a building obtains from outside,and it has an important impact on the heat transfer of the envelope.At this stage,the thermal design of the building envelope,heating and air conditioning load design,and building energy consumption calculations usually consider the influence of solar radiation It adopts two methods of outdoor comprehensive temperature and heat transfer coefficient correction coefficient to calculate the heat transfer of the envelope structure.Among them,in the heating design of the heating zone,the heat transfer coefficient correction factor is commonly used to calculate the building energy consumption index,so as to weigh the energy saving effect of the building,but the current specification clearly specifies the recommended value of the heat transfer coefficient correction factor in the main city of the heating zone The consideration of solar radiation is under the condition of steady-state heat transfer,and the consideration of specific environmental conditions is relatively rough.How to improve the accuracy of considering solar radiation heat in heating calculation is particularly important.In response to the above problems,the author carried out the following research.First,it briefly introduces the three basic heat transfer methods of heat conduction,convection and radiation of the building envelope,the surface heat transfer and the structure itself.At the same time,understand the basic performance of solar radiation,focusing on the heat transfer effect of solar radiation in non-transparent envelopes and transparent envelopes.The theoretical calculation method of heat is used to derive the formula,and the method of using its parameters is detailed.Secondly,using the external surface temperature in the measured data and the heat flux intensity through the envelope as the standard,the results calculated by the two theoretical methods considering the effect of solar radiation,such as the outdoor comprehensive temperature and the heat transfer coefficient correction coefficient,are compared with the measured data.difference.The study found that the average value of the external surface temperature when the outdoor comprehensive temperature and the correction coefficient are used for the south-outer wall of Xi'an is 2.7? and 7.7? lower than the measured average temperature of the south-outer wall respectively;and the Kunming area is 3.5? and 9.2? lower.The average heat flux intensity when the outdoor comprehensive temperature and the correction coefficient are applied to the south outer wall of Xi'an area is 31% and 52.7% lower than the average heat flux intensity measured by the south outer wall respectively;and the Kunming area is 50.7% and 68.3% lower,respectively.The result analysis concludes that when the surface heat transfer coefficient is fixed,the outdoor integrated temperature is used to calculate the heat transfer of the envelope structure is closer to the actual measured value than the correction coefficient,and the reasons for the difference between the two theoretical calculation results are briefly analyzed.Finally,by comparing the difference between the theoretical calculation results of the outdoor comprehensive temperature and the correction coefficient and the actual measurement,the unsteady heat transfer is used to consider the thermal effect of solar radiation on the envelope structure to optimize the heat transfer coefficient correction coefficient of the external wall of the heating building.And compare the difference of correction coefficient before and after optimization.The results show that the optimized heat transfer correction coefficient can reduce the heat transfer heat consumption of the envelope structure,which further reduces the heating and heating energy and effectively saves energy.The recommended value of the correction coefficient of the heat transfer coefficient of the external wall of different orientations has different degrees of deviation from the optimized value,of which the southward deviation is the largest.At the same time,the optimized correction coefficient is used in energy consumption calculation and building unbalanced insulation design,which can effectively improve the accuracy of solar radiation on the thermal effect of the envelope structure in energy consumption calculation and building unbalanced insulation design.