Research On Solar Energy Photo-thermal Utilization Of Glass Window Containing Nano-PCM

Glazing window has the advantages of good lighting,ventilation and aesthetics,which is extensively used in buildings.However,due to high light transmission and weak thermal inertia of window,the indoor photo-thermal environment is affected and the energy consumption of window is significantly higher than that of other part.Filling with translucent phase change material paraffin can improve its thermal performance.Nevertheless,the low thermal conductivity and long phase transition time of paraffin lead to low energy storage/release efficiency,which restricts its photo-thermal efficiency in practice.Adding high thermal conductivity nanoparticle into paraffin can improve the thermal performance of paraffin and regulate the solar photo-thermal transmission process,but it is greatly affected by parameters such as particle type,volume concentration and size.Therefore,controlling the photo-thermal transmission process of solar energy in glazing window containing Nano-PCM by optimizing the nanoparticle parameter is an effective method to achieve the solar energy utilization,as well as improve the thermal storage performance of glazing window and reduce building energy consumption.In this paper,the research on the photo-thermal utilization of glazing window containing Nano-PCM was investigated.First,the physical parameters of paraffin containing nanoparticle were measured by experiments.And based on the experiment data,the heat transfer performance of paraffin-filled glazing window with or without nanoparticle were comparative analysis by software FLUENT,and the feasibility of improving the photothermal performance of paraffin containing nanoparticle was verified.Next,for engineering calculations and parameter optimization,the one-dimensional photo-thermal transfer model of glazing window containing Nano-PCM was established,and the impact of volume concentration,size and phase change layer thickness on the photothermal transfer was investigated,and then the parameters were optimized.Finally,the performance of glazing window containing Nano-PCM was evaluated in terms of energy consumption,economy,payback period and environmental benefits.The main contents of this paper are as follows:1)Based on the two-step method,several sets of paraffin containing nanoparticles with different particle types,volume concentration and size were prepared.Next,the thermal conductivity and transmittance spectra of paraffin containing nanoparticles in solid phase and liquid phase were investigated experimentally.Finally,the optical constants such as refractive index and absorption coefficient of paraffin containing nanoparticles were obtained by means of double-thickness method,which was used to supplement the two-dimensional heat transfer simulation of glazing window containing Nano-PCM.2)The two-dimensional unsteady heat transfer model of glazing window containing NanoPCM was established and the UDF code was compiled based on the external environmental conditions,and the influence of heat transfer performance under different seasonal and typical daily environmental time-varying factors were numerically investigated.3)To simplify the calculation model,a one-dimensional “radiation-heat conduction-phase transformation” coupled photo-thermal transfer model of glazing window containing Nano-PCM was established,and the effect of particle type,volume concentration,size and phase change layer thickness were investigated and the parameters were optimized.4)Based on the optimized results,the application effect of glazing window containing Nano-PCM was evaluated in terms of energy consumption,economy,payback period and environmental benefits in the whole life cycle.The research results enriches the physical properties parameters database of paraffin containing nanoparticles,and proves the advantages of glazing window containing NanoPCM in term of photo-thermal performance.Meanwhile,the parameters including volume concentration,size and phase change layer thickness were optimized,as well as the energy consumption,economy,payback period and environmental benefits were evaluated.The results can provide scientific reference for the engineering application and development of glazing window containing Nano-PCM,and provide an effective solution for achieving energy saving and improving indoor light and thermal environment.