Design And Performance Analysis Of Thermoelectrochromic Energy-saving And Energy-storage Smart Windows Based On Thermosensitive Hydrogel Composite Materials

With the rapid development of the economy and the increasing demand for occupant comfort,the energy demand for global buildings continues to grow.Improving the building envelope,especially the building window which is easy to lose energy,is crucial to reducing building energy consumption.The new smart window can not only provide excellent vision but also effectively regulate the transmittance of sunlight and reduce the energy consumption of temperature control equipment.At present,the development of smart windows is mainly thermochromic smart windows with passive strategy and electrochromic smart windows with active strategy.However,the two methods have their advantages and disadvantages.Researchers are devoted to combining passive strategy with an active strategy to improve people’s demand for building comfort,and at the same time play a synergistic effect on saving building energy consumption.Therefore,in this paper,based on the thermochromic smart window,the photothermal-electrochromic composite material of thermosensitive hydrogel was developed.Using the coupling strategy of passive and active technologies,the thermo-electrochromic smart window was designed to explore its controllable optical performance,phase change performance,and energy saving/enery storage performance.The research mainly includes the following three parts:(1)Design and performance analysis of smart window based on PNIPAm/PPy photothermal conversion composite thermochromic hydrogelHere,thermochromic PNIPAm/PPy NPs composite hydrogels were obtained the by in-situ polymerization growth method.Under the optimized PPy NPs concentration(0.125 mg/m L),the photothermal conversion efficiency reached 53.21%,and the phase transition of PNIPAm/PPy NPs could be rapidly achieved after 3 min of Xe lamp irradiation.After being irradiation for 20 min,the simulated indoor temperature was 3.5°C lower than that of the traditional glass window.Furthermore,the effect of PPy electrochromic film on the phase transition performance of PNIPAm was explored.The PPy film was immobilized on the FTO conductive glass by an electrochemical deposition method,and the design of the PNIPAm/PPy integrated intelligent window was obtained by encapsulation.Based on colour regulation,the time of phase transition was 9.5 min longer than that of PNIPAm.(2)Dual-function smart windows based on HPC/PANI with dynamic and fast thermal response for building energy-saving/storageHere,a type of dynamic and fast phase transition of a thermochromic hydroxypropyl cellulose(HPC)hydrogel was designed,whose phase transition can be triggered by the dynamic photothermal effect of optothermal-electrochromic polyaniline(PANI)films.The thermoelectrochromic device(T-ECD)not only exhibits wide range adjustment of phase transition temperature(20-49?C),switchable colour tones(light yellow to purple),visible luminous transmittance(15.70-75.53%),and high solar modulation efficiency(60.89%).In addition,a field test further demonstrates that the house model equipped with the T-ECD can reduce the indoor temperature by 13.3°C compared with that using a traditional glass window.Furthermore,combined with photovoltaic devices for energy storage,building window energy saving/energy storage integration.(3)Design and performance analysis of high efficiency thermo-electrochromic smart window for energy storage based on PANI/MXene heterojunction electrodeHere,the MXene film transparent conductive layer material was prepared by the interface self-assembly method.PANI/MXene composite film was synthesized by electrochemical polymerization on the surface of MXene film.The experimental results show that PANI is successfully polymerized and grown in the interlayer and surface of MXene,showing a loose network structure.the improvement of hydrophilicity of PANI/MXene is beneficial to ion migration and adsorption in the electrolyte.The specific capacitance of PANI/MXene film is 21.54 m F/cm~2 at a low current density(0.1 m A/cm~2),which is significantly higher than that of pure PANI film(11.54 m F/cm~2).When the power density is 1.92 m W/cm~2,the energy density can reach 618.42 m Wh/cm~2,and the energy density of the PANI/MXene electrode is significantly better than that of the pure PANI electrode.It shows that the intelligent window has high energy storage performance,showing a good prospect for window energy storage applications.