Theoretical And Experimental Investigation On The Diffuse-to-diffuse Radiation Of VDSF With Blinds

Solar radiation has an important influence on the energy consumption of air conditioning and lighting in buildings with VDSF. Inorder to reduce energy consumption, avoid direct solar radiation and make full use of diffuse solar radiation for lighting as possible. Inevitably, the indoor diffuse radiation will become to heat gain and affectionthe air conditioning loads. So it is necessary to develop a model to calculate out the heat gain of indoor diffuse radiation.The indorr diffuse radition include direct-to-diffuse radiation and diffuse-to-diffuse radiation and scholars have made a lot of research on the former. While researchers usually make approximations to the latter, we call this method as approximate model. The parameters of diffuse-to-diffuse in approximate model are considered as constant and the diffuse-to-diffuse radiation directly pass through the blind gap is ingored. The approximate model can not simulate the process of diffuse-to-diffuse of blind because of that limitation. So the integral modelbe developed to solve that problem.Firstly, divide the incident angle into four parts and calculate the parameters of diffuse-to-diffuse in each part independently. The integrated transmittance of sky diffuse radiation and ground diffuse radiation is calculated through integral. Then the integrated transmittance of blind is calculated through law of conservation of energy; the influence of various factors on the parameters of diffuse-to-diffuse of blind is studied.Then, the experimental platform is built and single variable experiment is conducted. By changing the blind angle and the weather condition, the diffuse-to-diffuse transmittance of VDSF with blinds and indoor solar heat gain are calculated and compared with the results obtained by experiment and approximate model.Finally, use the integral model and the approximate model to simulate the temperature of each layer of VDSF and contrast the results with the experiment value to study the affection of diffuse-to-diffuse radiation on the thermal performance of VDSF.Study results show that the heat gain of indoor diffuse-to-diffuse radiation is the main reason of the indoor solar heat gain. The integral mode can simulate the process of diffuse-to-diffuse more accurately than the approximate model, it plan a important role in calculating the energy consumption of air conditioning and lighting in buildings with VDSF.