Performance Analysis Of PV-ETFE Cushion System Under Multiphysical Conditions

As a new type of building material,ETFE(Ethylene-tetrafluoroethylene)membrane has many advantages such as light weight,impact resistance,high light transmittance,stable chemical property and good self-cleaning property.It is widely used in large-span buildings.The flexible photovoltaics(PV)has good flexibility and high temperature adaptability.If the ETFE cushion and the PV are combined into a building integrated photovoltaic(BIPV)building,the solar photovoltaic can easily converted solar irradiation into photoelectricity and heat for the cushion which can effectively reduce building energy consumption.Because the performance of PV-ETFE cushion has complex long-term,time-varying and dynamic characteristics,it is difficult to measure its performance parameters comprehensively,so it is necessary to establish a reasonable numerical analysis model,analyze the comprehensive performance of the cushion system and reveal more profound problems.In addition,PV absorbs external light radiation and then the surface temperature rises sharply,its photoelectrical properties will certainly be affected.Besides,ETFE film has property of high temperature sensitivity and its mechanical properties will also have a certain response with temperature changes.Therefore,it is necessary to study the electro-thermo-mechanical properties of PV-ETFE composite from the aspect of material.First of all,based on the performance test of the three-layer PV-ETFEcushion in summer,the photoelectric-thermal-structural performance of the cushion system was summarized.Based on the analysis results of actual test environment and the cushion performance,we set up the multiphysical model and the thermos-fluid coupling model respectively with respect to irradiance,the temperature field,structural field and inner liquid field of PV-ETFE cushion.Then,multiphysical coupling model was established in COMSOL Multiphysics.Membrane mechanical properties,thermal field and internal fluid field distribution of the three-layer PV-ETFE cushion were obtained.After that the results between the experiment and numerial simulation were compared to verify the rationality and accuracy of the numerical model.All the results in this chapter could serve as a reference in the process of design and construction for PV-ETFE cushion.Finally,the material composite method of flexible thin film solar cells and ETFE films was studied.Uniaxial tensile tests of different forms of flexible OPV-ETFE composites were carried out under the illumination condition of 1000 W/m~2 irradiation.The stress-strain curves,temperature and voltage variation curves were obtained and the interaction between photoelectric-thermal-mechanical properties is analyzed.The fifth chapter built a numerical analysis model of flexible OPV-ETFE composite to study its photothermal-mechanical properties and then analyzed of coupling properties of OPV-ETFE materials in multi-physical field.This study can serve as a foundation research for the flexible OPV-ETFE air cushion system.