Investigation On The Comprehensive Performance Of Novel Photovoltaic/Thermal Window/Wall And Their Impact On Indoor Environment

Currently,the building run carbon emissions account for around 21%of the total carbon emission of our society,and the CO2 emissions produced by building run mainly come from the consumption of fossil energy in the building run process.Reducing building energy consumption and carbon emissions,and increasing the use of renewable energy in buildings are the powerful driver for achieving the "dual carbon"goal,and it is also the top priority in "14th Five-Year Plan".Solar energy is clean,stable and widely distributed renewable energy,while buildings have a large radiation receiving area,which is a favorable carrier for solar energy utilization.Therefore,the combination of solar energy utilization technology and building envelope is the important method to achieve zero-carbon and zero-energy buildings.Building facades(windows and wall)are the main part of the envelope of modern buildings,and are also a research hotspot of building integrated solar energy.In view of a series of problems of PV window and PV wall at present,such as low electrical efficiency,poor indoor luminous/thermal environment,low solar energy utilization rate,and poor seasonal/climate suitability,this thesis proposed two novel solar PV/T comprehensive utilization system suitable for building exterior walls and exterior windows,respectively:(1)CdTe double-skin ventilated window(CdTe-DSV window).The CdTeDSV window combines the CdTe PV glass with passive cooling/heating technology.While generating electricity,it has multiple functions such as improving indoor luminous environment,shading in summer,and heating in winter.Its innovations include:applying semi-transparent and high-efficiency CdTe PV glass to building exterior windows,and can significantly improve electrical efficiency and indoor luminous environment;possessing a variety of work modes,and can meet the building air-conditioning demand in different seasons or different climates;utilizing the waste heat of PV glass for passive cooling/heating to realize the comprehensive PV/T utilization of solar energy on the surface of building exterior windows.(2)built-out multifunctional PV/T wall(EMFPV/T wall).The EMFPV/T wall combines crystalline silicon cells with passive heating technology and active hot water technology.While generating electricity,it has various functions such as heating in winter,cooling in summer,and supplying hot water in non-heating seasons.Its innovations include:Combining the traditional solar water-heating system and the solar air-heating system to achieve passive heating in winter and active cooling in summer,and can meet the building air-conditioning demand in different seasons;ensuring the PV efficiency throughout the whole year,and realizing the continuous solar utilization of PV/T throughout the whole year,and having a high annual utilization rate of solar energy;The PV cells are placed outside the glass cover to further improve the PV efficiency and reliability of the PV wall.On the basis of the above research,a control strategy based on artificial neural network(ANN)was proposed to regulate the work mode of CdTe-DSV window and MFPV/T wall to achieve the maximum utility of the system.For the above-mentioned CdTe-DSV window and EMFPV/T wall,as well as the ANN control method,the following works were mainly conducted in this thesis:(1)the CdTe-DSV window was proposed and the experimental platform was built.The solar heat gain performance,thermal insulation performance,power generation performance and daylighting performance of the window were dynamically tested.The experimental results showed that the solar heat gain coefficient of the window was 0.28 and the PV efficiency was 7.1%in the internal circulation mode,the solar heat gain coefficient was 0.11,the electrical efficiency was 6.2%in the external circulation mode,and the thermal insulation coefficient at night was 2.05W/m2K,the useful illuminance index of the window was 84%during the experiment period.The CIE standard chromaticity diagram method and the EnergyPlus daylighting model were used to evaluate the indoor luminous environment of the CdTe-DSV window.The results showed that compared with ordinary double-skin windows,the CdTe-DSV window could reduce the CCT of indoor light by 700～900 K,and maintain the CRI above 95.The window could improve the indoor UDI by 19%,prolonged the illuminance uniformity period by 68.7%,and reduced glare period by 64.1%.(2)The thermal-electrical model of the CdTe-DSV window was established and verified,and the model was used to evaluate the heat gain performance of the system and indoor thermal comfort.The calculation results showed that compared with ordinary single-layer window and CdTe single-layer PV window,the CdTe-DSV window could reduce heat gain in summer and heat loss in winter,and prolonged indoor thermal comfort time.Based on the above thermal-electrical-daylight model,the comprehensive building energy consumption performance of the CdTe-DSV window in cold regions,hot regions,and cold-winter and hot-summer regions was analyzed,and the structure of the window was optimized.The results showed that compared with ordinary double-skin windows,the optimized CdTe-DSV window could reduce net building energy consumption by 11.2%,25.8%,and 6.6%in Hefei,Haikou,and Harbin.(3)The EMFPV/T wall was proposed and the experimental platform was built.the water-heating performance,air-heating performance and power generation performance of the system were dynamically tested.The experimental results showed that in the PV/air mode,the maximum temperature difference between the inlet and outlet of the air cavity of the wall was around 9℃,the average electrical efficiency of the wall throughout the day was 13.8%,and the average thermal efficiency was 18%.In the PV/water mode,the temperature of the water tank increased first and then decreased.The temperature rise of the water tank could reach a maximum of 26℃.The average electrical efficiency of the wall throughout the day was 14.09%,and the average thermal efficiency was 9.07%.(4)The thermal-electrical model of the EMFPV/T wall was established andverified,and the thermal,electrical and exergy performance of the built-in and builtout multi-functional PV/T walls was simulated and compared based on the established model.The simulation results showed that compared with the built-in multifunctional PV/T wall,the power generation of the EMFPV/T wall was higher,but the heat gain was reduced.Considering the difference in energy quality between heat and electricity,the proposed wall had higher exergy efficiency.The thermal-electrical model of the EMFPV/T wall was linked into building energy simulation software.Based on this simulation method,the annual energy consumption performance of the EMFPV/T in the cold-winter and hot-summer regions was simulated.The simulation results showed that compared with the ordinary external walls,the energy saving rates in Nanjing,Shanghai,Wuhan and Chongqing were 43.5%,48.2%,36.4%and 34.6%.(5)An operation control strategy of building integrated PV/T system based on ANN was proposed.this strategy was used to control the work modes of CdTe-DSV window and EMFPV/T wall.The calculation results showed that compared with the traditional control strategy,the ANN control strategy could prolong the indoor thermal comfort time and reduce the building cooling and heating load.Using the numerical model of the CdTe-DSV window and the MFPV/T wall,the energy saving potential of the ANN-controlled two systems in the plateau area was calculated.The results showed that the energy saving rates of each plateau city were 114%in Mexico City,66%in Quito,63%in Bogota,51%in Lhasa,49%in La Paz,40%in Xining.