纳米透明隔热涂料的研制

将纳米ATO与水性聚氨酯通过一定的工艺制备出纳米隔热涂料,在常温下将之涂在玻璃表面制成低辐射玻璃。光学性能分析表明其具有较好的隔热效果,6mm厚白玻璃涂布后遮阳系数SC小于0.67,且可见光透过率较高,大于63%,并且玻璃表面光滑平整可视性好,具有良好的市场前景。     

Solar optical properties of windows

To properly calculate dynamic solar gain in buildings, one must know the optical properties of the window in detail. In this paper, we develop a complete set of calculation procedures for determining the solar transmittance, reflectance, and absorptance of a window composed of an arbitrary number of partially transparent layers. Any layer may have a thin-film multilayer coating, such as an anti-reflection coating for increasing solar transmittance, a solar control film for reducing solar heat gain, or a transparent heat-reflecting mirror for improving thermal resistance. The results of sample calculations are given over the range of incidence angles for conventional and advanced energy conserving window designs.     

红外灯辅助喷雾热解法制备可控锑掺杂氧化锡透明热反射薄膜

本文以乙二醇为溶剂及配位剂,以冰乙酸为酸性催化剂,采用溶胶−凝胶法制备均一稳定的具有不同锑掺杂浓度的二氧化锡（SnO2）溶胶,再通过红外灯辅助喷雾热解法制备性能优异的可控锑掺杂SnO2薄膜,并对薄膜微结构、光电性能进行表征。结果表明：薄膜以四方金红石结构存在,结晶完全;方阻值随锑掺杂浓度和成膜厚度的增加而降低;薄膜在可见光区的平均透过率可达79%左右,且在中远红外光区的平均反射率可达80%左右。此外,通过改变锑掺杂浓度和成膜厚度,能够有效地调节薄膜的红外反射率与反射起点波长,从而满足不同气候条件对热反射和热发射的不同要求。     

Development of a mathematical model for a curved slat venetian blind with thickness

This article is about the development of a mathematical model for a venetian blind. The model is used for determining the performance of the glass window installed with a venetian blind in term of heat transmission. The blind, whose optical properties are considered nonspecular, is modeled as an effective layer. The optical properties of the effective layer are mainly dependent on the slat angle, slat properties and solar profile angle. The effect of slat curvature and the effect of slat thickness are included in the developed model. The shortwave optical properties of the effective layer, transmittance, reflectance and absorptance, are classified as the optical properties for direct radiation and the optical properties for diffuse radiation. The analysis for optical properties due to the interreflection of the direct radiation between the adjacent slat surfaces is done by using radiosity method on a 6 surface closed enclosure. The effect of the slat curvature and thickness causes the shaded area blocked by the blind itself increased in certain cases. The optical properties for diffuse radiation of the effective layer are determined considering the incident diffuse radiation from the sky and from the ground. The optical properties calculated from the developed model are also compared to the results obtained from the three previous models. The validation of the results predicted by the developed mathematical model is performed by comparing the predicted results with the experimental results. The results that used to validate in this study is the ratio of the transmitted radiation through the glass window installed with venetian blind to the incident radiation on the glass window. It is shown from the comparison that the developed mathematical model for the venetian blind included the curvature and thickness effect yields quite accurate predicted results.     

Effect of rapid thermal annealing on optical properties of zinc sulphide thin films

Zinc sulphide (ZnS) thin films were prepared on clean surface glass substrates by thermal evaporation under pressure of 10^?5?Torr. Thickness of thin films was uniform 55?nm measured by ellipsometry. These films were also kept into a quartz glass tube for rapid thermal annealing at 30 and 60?s by using a 500?W halogen lamp for crystalline the structure. The cubic structure of the films was verified by X-ray diffraction and the intensity of predominant peak increases with annealing time. The optical absorption study was carried out by UV–ViS–NIR spectrometer in the range of 200–800?nm. The optical band gap changes from 3.48 to 3.08?eV, with rapid thermal annealing. Thermo electric power studies confirm the n-type nature of ZnS thin films and thermoelectric power increases with increase in temperature. This study is important because ZnS is potentially important material for antireflection coating and window layer material in hetero-junction solar cells.     

Solar optical properties of thin films of Cu, Ag, Au, Cr, Fe, Co, Ni and Al

The optical properties of metal coated glass substrates have been investigated. Thin films of various thicknessesof the noble metals: Cu, Ag, Au, the transition metals: Cr, Fe, Co, Ni and the free electron-like metal Al were thermally evaporated onto glass substrates. The front and backside reflectance and the transmittance between 0.35 and 15 μm were measured. The obtained data were used to calculate the integrated values of solar reflection and transmission as a function of metal film thickness. The application of metal films on domestic windows as sun-screens and heat-mirrors are discussed. It is concluded that Cu is the best coating in a window system if good heat insulating properties are desired. This is due to its ability to remain continuous at very thin film thicknesses. An infra-red reflectance of 86 per cent combined with a solar transmittance of 55 per cent was obtained for a 70film. For solar heat-protection Au-films are found to be superior owing to their transmittance peak in the middle of the visible wavelength region. The transition metals are less selective than the noble metals, but due to their flat response-curves in the visible range they cause a smaller change in colour of the transmitted and reflected light.     

Solar-control films

The magnitude of the transmittance of solar radiation through glass is dependent upon its angle of incidence, the emissivity of the glass surface and the length that the light beam travels through the glass. To alter the emissivity of a glass surface a solar-control film can be attached to it. However, none of the present generation of ‘solar’ films that are applied to transparent glass surfaces is able to inhibit insolation gain during the summer while providing satisfactory thermal-radiation insulation with respect to energy leaving the building during the winter. This is because different wavelengths of radiation need to be inhibited for these two processes to be successful, namely short-wave radiation in the case of insolation and long-wave radiation for thermal insulation. Neither of these films inhibits glare satisfactorily. As expected, the energy transmittance and rate of heat gain by the affected room decrease as the angle of incidence (of the energy source, i.e. the sun, with respect to the glass) increases. Also the magnitude of this rate of heat gain depends upon the type (reflective, insulating or absorptive) of solar-control film applied to the glass.     

Optimization of antireflection coating for VO2-based energy efficient window

Vanadium dioxide (VO₂) films have been proposed as energy efficient window coatings for their thermochromism, with which the solar energy transmission in the IR region may be controlled passively. These coatings suffer from low visible (or luminous) transmission (380–760 nm in wavelength), which hinders their practical uses. We here consider an antireflection (AR) coating for the VO₂-based window. Optical calculation was first performed upon a basic structure for thermochromic window composed of a VO₂ layer on glass with an AR layer of refractive index n and thickness d. Optimization was carried out on n and d for a maximum integrated luminous transmittance (T_lum). The calculation demonstrates that the optimal n value changes with thickness of VO₂, and at n≈2.2 it gives the highest T_lum enhancement from 32% (without AR coating) to 55% for 50-nm VO₂. Experiment was done on a structure of 50-nm VO₂ on quartz glass using ZrO₂, of which n≈2.2 matching the best n value, as AR coating. Formation of an optimized structure, ZrO₂ (56 nm)/VO₂ (50 nm)/quartz, was done by sputtering, and its optical properties were characterized with spectrophotometry. An improvement of T_lum from 32.3% to 50.5% was confirmed for the semiconductor phase with similarity also for the metallic one. The IR switching properties were not much deteriorated.     

磁控溅射电致变色非晶态氧化钨薄膜

利用平面磁控反应溅射在具有透明导电膜的玻璃基片上沉积氧化钨膜层。Ｘ射线衍射分析结果表明，基片在室温状态下得到的膜呈非晶态。以０．２Ｎ浓度的ＨＣｌ为电解液，用电化学方法研究了Ｈ＋注入及抽出后氧化钨膜光学性能的变化及这种变化与膜的制备参数之间的关系。获得了沉积氧化钨膜近于最佳的工艺条件。在纯氧气氛下，溅射功率密度１．２Ｗ／ｃｍ２，溅射气体压强１．３Ｐａ时，制备的非晶态氧化钨膜，在５０次电化学循环后，漂白态与着色态的可见光透射率之差约为０．５７，其电化学循环的变色寿命也长。光电子能谱（ＸＰＳ）分析表明，Ｈ＋注入后着色态膜内出现了Ｗ５＋、Ｗ４＋。对电致变色机理也作了讨论。     

Visual and energy performance of switchable windows with antireflection coatings

The aim of this project was to investigate how the visual appearance and energy performance of switchable or smart windows can be improved by using antireflective coatings. For this study clear float glass, low-e glass and electrochromic glass were treated with antireflection (AR) coatings. Such a coating considerably increases the transmittance of solar radiation in general and the visible transmittance in particular. For switchable glazing based on absorptive electrochromic layers in their dark state it is necessary to use a low-emissivity coating on the inner pane of a double glazed window in order to reject the absorbed heat. In principle all surfaces can be coated with AR coatings, and it was shown that a thin AR coating on the low-e surface neither influences the thermal emissivity nor the U-value of the glazing. The study showed that the use of AR coatings in switchable glazing significantly increases the light transmittance in the transparent state. It is believed that this is important for a high level of user acceptance of such windows.     

附着液滴的玻璃层太阳辐射传递模型

针对液滴和玻璃层的太阳辐射传递特点,提出附着液滴玻璃层的太阳辐射传递模型。将入射的太阳辐射进行直散分离,基于蒙特卡洛射线追踪法对直射辐射光学性能进行计算,同时将入射角进行离散,分别在各角度范围内采用蒙特卡洛射线追踪法的直射辐射原理计算散射辐射光学性能。为了对模型进行验证,通过实验测试液滴覆盖率和太阳入射角对附着液滴玻璃层光学性能的影响,并与模型计算结果进行比较。结果表明：实验结果与计算结果差别较小,总透过率最大误差仅约为0.05,模型的准确性较高。附着液滴的玻璃层能有效降低太阳辐射透过率,且太阳辐射透过率随液滴覆盖率的增大而减小,随入射角的增大而减小。     

U-values, optical and thermal coefficients of composite glass systems

This paper presents a different approach for thermal effective windows, i.e. windows which reduce energy transmitted into or out of the room. The idea is to use a double-sealed glass filled with pcm whose fusion temperature is determined by solar-thermal calculations. The investigation is divided into two main parts: modeling of the heat and radiation transfer through the composite window and the optical investigation of the pcm-filled window. A one-dimensional thermal model for the composite window was developed to predict the resulting effects due to variation of the geometrical and pcm thermal properties. Optical investigations using photo-spectrometry were realized on single glass, double glass filled with air, and double glass filled with pcm. The transmittance and reflectivity tests indicate large reductions in the infrared and ultraviolet radiations while maintaining the good visibility. The effects of thickness of glass and spacing were also analyzed.     

The electrochromic properties of hydrated nickel oxide films formed by colloidal and anodic deposition

Hydrated nickel oxide NiO_xH_y films were deposited onto indium tin oxide (ITO) coated glass by two methods (i) colloidal precipitation and (ii) anodic electrodeposition. The electrochromic properties of hydrated nickel oxide films were studied by transmittance measurements (UV/VIS/NIR), and Fourier transform infrared reflectance spectroscopy as a function of the key deposition parameters. The solar transmittance was calculated for films switched in both bleached and coloured states. The best results were achieved for films produced by anodic electrodeposition from stable solutions with solar transmittance T_s(bleached) = 0.82 and T_s(coloured) = 0.22. Corresponding optimum values for the films produced by colloidal precipitation were solar transmittance T_s(bleached = 0.82 and T_s(coloured) = 0.47. Fourier transform spectrophotometry was used for elucidating changes in hydration, hydroxylation and for the characterization of structural characteristics in the bleached and coloured states. It was found that free OH stretching vibration at 3647 cm⁻¹ corresponds to Ni(OH)₂ for both anodic and colloidal deposited films in the reduced (bleached) state. In the oxidised state hydrogen bonded OH at 3360 cm⁻¹ is observed.     

Lighting and energy performance of solar film coating in air-conditioned cellular offices

In subtropical Hong Kong, the principal objectives of fenestration design include eliminating direct sunlight and decreasing cooling loads. To avoid the problems of glare, excessive brightness and thermal discomfort, occupants may block the windows with internal shading devices, resulting in poor daylighting performance and very small amount of electric lighting energy savings. Recently, the advances in thin film coatings for window glass products provide a means of substantially reducing heat gain without proportionally reducing daylight transmittance. It has been suggested that film coatings together with photoelectric lighting control systems could minimise the electric lighting and cooling requirements without causing undue visual and thermal discomfort to the occupants. This paper presents field measurements on solar control film coatings in fully air-conditioned offices in Hong Kong. Solar heat gains, indoor illuminance levels and the electricity consumption by the fluorescent luminaires were systematically recorded and analysed. Measurements were made for two cellular offices, one with solar control film coating on the window glass and the other without. The findings showed that the solar film coating could cut down energy expenditures for air-conditioned buildings, especially for spaces with large glazing areas subject to substantial amount of direct sunlight. Results are presented and the design implications discussed.     

纳米氮化锆薄膜的光学性能研究

采用射频磁控溅射法在载玻片和硅片上制备了纳米氮化锆薄膜。结果表明,纳米氮化锆薄膜(10～29nm)呈非晶态,其光学特性在波长380～2700nm的范围内平均可见光透过率为82.86%,平均反射率低至10.78%。扫描隧道谱(SIS)分析表明薄膜禁带宽度E_g为2.99 eV,在可见光范围内光子多为透过,反射和吸收较弱。从薄膜的X光电子能谱图(XPS)可知,薄膜表面存在大量的ZrO_2,对于纳米级的氮化锆薄膜而言,表面相ZrO_2对整体光学性能的影响较大。     

Investigations into the functioning of a supply air window in relation to solar energy as determined by experiment and simulation

‘Supply air windows’ under optimum flow conditions function as an efficient heat reclaim device. Heat escaping from the room, through the inner glass pane, is entrained in the air flow between the inner and outer sashes and returned to the room. A low-E coating to the inner glass acts as a barrier to radiation heat loss across the window so very low U-values can be achieved. These same characteristics enable the window to function as a passive solar component. Its efficiency is inferior to that of a dedicated passive solar device due to its transparency, but even so at modest levels of incident solar gain a worthwhile proportion is entrained into the air flow and supplied to the rooms as pre-heated ventilation air supply. These characteristics have been established by laboratory, test cell investigations, and simulations using computational fluid dynamics and ESP-r, a whole building dynamic thermal modelling tool.     

Characterization and degradation testing of nickel pigmented anodic alumina solar selective absorber films produced by alternate and reverse periodic plating technique

Nickel pigmented anodic alumina solar selective absorber films have been prepared using alternate and reverse periodic plating technique. The films show favorable characteristics, high absorptance (α?=?0.97), low emissivity (??=?0.16), for the use as solar selective absorber materials. The effect of the alternate and reverse periodic plating parameters on the optical and films microstructural properties has been studied. Optical and structural properties of the films are investigated using X-ray diffraction, TEM, SEM, EDS, UV/VIS/near IR. These investigations reveal that the nickel particles in alumina pores are spherical with average crystals size ranged from approximately 150–300?Å. The optical characteristics of the films with the preparation conditions are compared. The stability of the films to high temperatures and humidity has been tested. The results from these tests show that the reverse periodic plated films are more sensitive to degradation process mainly nickel oxidation.     

ITO/ATO/TiO2 triple-layered transparent conducting substrates for dye-sensitized solar cells

A novel transparent conductive oxide film based on the triple-layered indium tin oxide (ITO)/antimony-doped tin oxide (ATO)/titanium oxide (TiO₂) has been developed for dye-sensitized solar cells by using radio frequency magnetron sputtering technique. Effects of the absence and presence of TiO₂ layer and the ITO layer thickness were investigated. Deposition of ATO layer was found to stabilize the thermal instability of ITO. Little change in sheet resistance and optical transmittance was observed by introduction of insulating thin TiO₂ layer on top of the ATO layer, whereas photovoltaic performance was significantly influenced. The conversion efficiency was improved from 4.57% without TiO₂ layer to 6.29% with TiO₂ layer. The enhanced photovoltaic performance with addition of TiO₂ layer was attributed mainly to the improved adhesion and partially to the reduced electron loss at the ITO/ATO conductive layer. Increase in the ITO layer thickness resulted in a slight decrease in photocurrent due to the reduced optical transmittance. When compared with the conventional fluorine-doped tin oxide (FTO), the ITO/ATO/TiO₂ conductive material exhibited similar photocurrent density but higher photovoltage and fill factor, resulting in better conversion efficiency.     

Modeling and simulation of a simple glass window

This paper presents a mathematical model with numerical simulations of the heat transfer across a simple glass window. The model is two-dimensional, transient based upon the energy equation with a source term to account for the solar radiation absorbed through the glass sheet. Variable incident solar radiation and external ambient temperature are considered in the numerical simulations. The governing equations and the associated boundary conditions are discretized by the finite difference approach and the ADI scheme. Numerical simulations are realized for the cases of clear and absorbing glass to show the effect of the glass thickness on the total heat gain, the solar heat gain and the shading coefficient.     

PCM glazing systems

This paper presents a different approach for thermal effective windows, i.e. windows that reduce the energy transmitted into or out of a room. The idea is to use a double sealed glass filled with a phase change medium (PCM) whose fusion temperature is determined by solar–thermal calculations. The PCM used is polypropylene glycol. The investigation includes modelling of the heat and radiation transfer through a composite window and optical investigation of conventional and PCM filled windows, testing of the window and comparison with numerical simulations. A one-dimensional model for the composite glass window is developed to predict the thermal performance as a function of the geometrical parameters of the panel and the PCM used. Optical measurements were realized using photo-spectrometry to determine the transmittance, reflectance and absorptance. The specimens used include single glass of different thicknesses, double glass of different gap spacing and thicknesses filled with air or PCM, and finally coloured PCM. The results indicate big reductions in the energy transmitted, specially in the infra-red and ultraviolet regions, while maintaining a good visibility. © 1997 by John Wiley & Sons, Ltd.