Solar control characteristics of Cu2Se coatings
TL;DR: In this article, the solar control properties of Cu2Se thin film coatings were investigated and the results are presented, which show that they exhibit superior solar control characteristics in certain respects over the metallic and PbS coatings and have comparable characteristics with CuxS films.
Abstract: Solar control coatings required for architectural glazing applications in tropical locations warrant much attention due to their vital role in energy conservation. The solar control properties of Cu2Se thin film coatings were investigated and the results are presented. It was observed that Cu2Se coatings have moderate optical transmittance and low reflectance in the visible region and high reflectance and low transmittance in the IR region. These characteristics are useful for the above purpose. The evaluation of their solar control parameters in the visible and IR region showed that they exhibit superior solar control characteristics in certain respects over the metallic and PbS coatings and have comparable characteristics with CuxS films.
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TL;DR: In this article, the authors presented a mathematical model and results of numerical simulations of a double sheet ventilated glass window, where the incident solar radiation heats up the air between the glass sheets creating buoyancy forces that induces upward flow of air.
Abstract: This paper presents a mathematical model and the results of numerical simulations of a double sheet ventilated glass window. The incident solar radiation heats up the air between the glass sheets creating buoyancy forces that induces upward flow of air. The two-dimensional transient model is formulated based upon the fundamental equations of mass conservation, momentum and energy, the associated constant and time varying boundary conditions and is solved by finite difference approach and the ADI (alternating direction implicit) scheme. The numerical grid and the time increment were optimized and the numerical results were validated against available data. Results of the temperature field along and across the channel are obtained for different spacing between the glass sheets and incident radiation conditions. The effects on the solar heat gain coefficient and the shading coefficient were also presented and discussed.
64 citations
TL;DR: In this paper, a mathematical model with numerical simulations of the heat transfer across a simple glass window is presented, which is two-dimensional, transient based upon the energy equation with a source term to account for the solar radiation absorbed through the glass sheet.
Abstract: 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.
47 citations
TL;DR: In this paper, the authors presented a study on a ventilated window composed of two glass sheets separated by a spacing through which air is forced to flow, and the model is one dimensional and unsteady based upon global energy balance over the glass sheets and the flowing fluid.
Abstract: This paper presents a study on a ventilated window composed of two glass sheets separated by a spacing through which air is forced to flow. The proposed model is one dimensional and unsteady based upon global energy balance over the glass sheets and the flowing fluid. The external glass sheet of the cavity is subjected to variable heat flow due to the solar radiation as well as variable external ambient temperature. The exchange of radiation energy (infrared radiation) between the glass sheets is also included in the formulation. Effects of the spacing between the glass sheets, variation of the forced mass flow rate on the total heat gain and the shading coefficients are investigated. The results show that the effect of the increase of the mass flow rate is found to reduce the mean solar heat gain and the shading coefficients while the increase of the fluid entry temperature is found to deteriorate the window thermal performance.
41 citations
TL;DR: In this paper, the structure of the films was analyzed using Grazing Incidence X-ray Diffraction (GIXRD) and High Resolution Transmission Electron Microscopy (HRTEM) analyses.
Abstract: Cu2Se nanocrystal (NC) films of different nanocrystal sizes were synthesized using vacuum deposition technique. The structure of the films was analyzed using Grazing Incidence X-ray Diffraction (GIXRD) and High Resolution Transmission Electron Microscopy (HRTEM) analyses. Band gaps of the films were found to decrease with increase in grain size. Analysis of the Raman spectra of the Cu2Se NC films showed that the exciton-phonon coupling in the films could be tuned by varying the grain size. DC conductivity of the films was found to increase and the activation energy for conduction to decrease with increase in the grain size of the samples. The grain size dependent conductivity along with the optical properties of the Cu2Se NC films may find practical applications such as window material for solar cells.
20 citations
TL;DR: In this paper, the thermal behavior of a ventilated double glass window with a solar reflective film is numerically investigated and validated against results available in the literature, and the results show that in order to reduce the heat gain in the internal ambient, the optimum spacing between the glass sheets should be at least 2.5 cm.
Abstract: In the present study, the thermal behavior of a ventilated double glass window with a solar reflective film is numerically investigated and validated against results available in the literature. The objectives of the study are to develop a validated robust thermal model for the ventilated double glass window, make it versatile so that it can incorporate different inserts (such as reflective and absorptive films, etc.), different glass sheets and different fluids and can be integrated with other available design tools. The proposed ventilated double window is composed of two glass sheets separated by a gap forming a channel having a solar reflective film on the internal surface of outer glass sheet. The model is based on the equations of mass, momentum and the energy conservation equations in steady state. Boussinesq approximation is used to evaluate buoyancy term. The discretization of conservative equations is done using the finite volume method. A numerical code is developed and validated against available experimental and numerical results. Thermal performance of the ventilated double glass window is assessed under different conditions and the results show that in order to reduce the heat gain in the internal ambient, the optimum spacing between the glass sheets should be at least 2.5 cm. The solar reflective film in a ventilated double glass window can reduce the penetrating solar energy by about 64.7% in comparison with a traditional double glass window.
17 citations
References
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12 Dec 1989
TL;DR: In this article, the possibilities of producing large area coatings with very low capital investment is an inherent attraction of chemical bath deposition technique, which makes the chemically deposited metal chalcogenide films as a low-capital alternative to the commercially available magnetron sputtered metallic coatings in the production of solar control glazings.
Abstract: Chemically deposited PbS, CuxS and PbS-CuxS thin films possess a range of solar control characteristics suitable for architectural window glazing applications in locations with a generally warm climate or subjected to extreme climates. The possibilities of producing large area coatings with very low capital investment is an inherent attraction of chemical bath deposition technique. This aspect makes the chemically deposited metal chalcogenide films as a low-capital alternative to the commercially available magnetron sputtered metallic coatings in the production of solar control glazings.
10 citations
12 Nov 1987
TL;DR: In this paper, thin metal coatings have been used for several years as selective radiation filters in architectural window applications, usually produced by vacuum deposition techniques such as evaporation or sputtering, and coatings are deposited either directly onto glass, or onto polyester film which is then laminated to glass.
Abstract: Thin metal coatings have been used for several years as selective radiation filters in architectural window applications. These coatings are usually produced by vacuum deposition techniques such as evaporation or sputtering, and coatings are deposited either directly onto glass, or onto polyester film which is then laminated to glass. Recently, metal coatings have begun to be used as reflectors in lighting and other applications.
10 citations
TL;DR: In this article, CdTe thin films were studied in this regard for use as an effective solar control coating and the films were characterized with respect to the film parameters such as film thickness, substrate temperature and deposition rate.
Abstract: Solar control coating refers to solar radiation filters applied on glazings of buildings in tropical countries. CdTe thin films were studied in this regard for use as an effective solar control coating. The films were characterized with respect to the film parameters such as film thickness, substrate temperature and deposition rate. On calculating the solar control parameters of various films, it was observed that the solar control parameters of the films depend on the above film parameters. CdTe films were found to be a better solar control coating than the commercial metallic coatings and exhibit comparable characteristics with CuxS and PbS films.
9 citations
12 Nov 1987
TL;DR: In this article, dual-target reactive magnetron sputtering was used to produce 0.3pm-thick ZnO films with -1% luminous absorptance, thermal infrared reflectance, and dc resistivity of ≈5 x 10-4 Ω cm.
Abstract: ZnO:Al films were produced by dual-target reactive magnetron sputtering. The effects of different deposition conditions were investigated. Under optimized conditions, 0.3-pm-thick films had -1% luminous absorptance, ≈85 % thermal infrared reflectance, and a dc resistivity of ≈5 x 10-4 Ω cm. Rutherford Backscattering Spectrometry showed that the Al content was ≈2 at.%. Transmission electron microscopy showed that the crystallite size was ≈50 nm for films deposited onto unheated substrates.
4 citations