A Smart Window for Angular Selective Filtering of Direct Solar Radiation

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Rustam S. Zakirullin
Keyword(s):  
Solar Radiation ◽  
Light Transmission ◽  
Slope Angle ◽  
Optical Filter ◽  
Time Of Day ◽  
Direct Solar Radiation ◽  
Smart Window ◽  
Smart Windows ◽  
Solar Radiation Intensity ◽  
Parallel Strips

Thin-film grating coatings are proposed for smart windows to angular selective filtering of solar radiation. The gratings are formed by absorptive, reflective, or scattering parallel strips (made of chromogenic or other materials) alternating with directionally transmissive strips (untreated surface of pure glass) on two surfaces of the window pane(s). The smart window with grating optical filter has angular selective light transmission and partially or completely blocks the direct solar radiation in a preset angular range and transmits the scattered and reflected radiation without using the daylight redistribution devices. The results of numerical simulation and experimental confirmation of optimum slope angle of the strips on the pane(s), their widths, and relative position on two surfaces to minimize the directional light transmission of the window at the preset date and time of day taking into account orientation of the window to the cardinal, the latitude of the building, and the seasonal and daily distribution of the solar radiation intensity are demonstrated.

scholarly journals Smart window for angular selective filtering of solar radiation

2019 ◽  
Vol 124 ◽  
pp. 01002
Author(s):  
R. Zakirullin ◽  
I. Odenbakh
Keyword(s):  
Solar Radiation ◽  
Light Transmission ◽  
Slope Angle ◽  
Optical Filter ◽  
Angular Range ◽  
Smart Window ◽  
New Approach ◽  
Direct Radiation ◽  
Daily Change ◽  
Parallel Strips

A new approach to angular selective filtering of the solar radiation without using the sunlight redistribution devices is proposed. Parallel strips of chromogenic materials on two surfaces of the pane(s) form an optical filter having angular selective light transmission. Clarified methods to calculate the optimum slope angle of the strips on the pane(s), their widths and relative position on two surfaces considering the seasonal and daily change in the solar radiation, the location of the building and the window’s azimuth are presented. Such a smart window blocks the direct radiation in a preset angular range and transmits the scattered and reflected radiation that is provides comfortable daylighting indoors.

scholarly journals Diffraction in grating optical filters with angular-selective light transmission

2020 ◽  
Vol 44 (3) ◽  
pp. 343-351 ◽  
Author(s):  
R.S. Zakirullin
Keyword(s):  
Light Transmission ◽  
Incidence Angle ◽  
Slope Angle ◽  
Optical Filters ◽  
Time Of Day ◽  
Light Transmittance ◽  
Smart Windows ◽  
Input And Output ◽  
Parallel Strips ◽  
Complex Movement

The effect of diffraction on the directional light transmittance of grating optical filters designed for smart windows is studied. The filter has an angular selective light transmission due to two thin-film gratings formed by "non-transmissive" (absorptive, reflective or scattering) parallel strips on the surfaces of a single or double glazed window. Methods are considered for calculating the op-timal slope angle of two filter’s gratings, their relative position on the opposite window surfaces and the widths of the strips of both gratings to minimize light transmission on a specific date and time of day for a given latitude and longitude of the building and azimuth of the window. A meth-od has been developed for calculating the diffraction at the input and output gratings of the filter with regard for a complex movement of the Sun relative to the window and a corresponding change in the incidence angle of the solar beams on the gratings. To evaluate a decrease in the light transmittance of the filter due to diffraction, an additional factor is introduced into the calcu-lation equation. Geometric parameters of the filters and diffraction are calculated. The values of the diffraction factor are 0.9999992 and 0.9999998 for single or double glazed windows, respec-tively, i.e., the influence of diffraction on the light transmittance of the grating filter can be ne-glected.

Daylighting Dynamic Control by Smart Window with Grating Optical Filter

2021 ◽  
pp. 27-32
Author(s):  
Irina A. Odenbakh
Keyword(s):  
Solar Radiation ◽  
Dynamic Control ◽  
Optical Filter ◽  
Thermal Conditions ◽  
Working Hours ◽  
Time Of Day ◽  
Light Transmittance ◽  
The Sun ◽  
Smart Window ◽  
Solar Radiation Intensity

A smart window with a novel grating optical filter is proposed, which supplies dynamic daily and annual control of window transmission without the use of blinds and similar devices. The filter attenuates direct solar radiation, letting in diffused and reflected radiation, thus creating more comfortable conditions for daylighting, insolation, and sun protection in rooms. A method for calculating the grating filter is changed and numerical modelling is conducted to show the capabilities of the new method of dynamic control of transmission. The optimal geometric parameters of the filter for a single-glazed smart window at a given azimuth of the window orientation are determined. The hourly values of the light transmittance of the filter during daylighting hours are calculated for the 15th day of each month from April to September, and the theoretical angular characteristics of the transmission of the filter, corrected for reflection and absorption, are constructed. The average monthly values of the theoretical and corrected light transmittance of a smart window are obtained, based on the results of calculations every hour compared to the time of day when the azimuths of the Sun and the window are equal. It is shown that the smart window with the built-in grating optical filter provides the minimum transmission at a given time of the day, taking into account the azimuth of the window, the geographic coordinates of the building, the seasonal and daily distribution of the solar radiation intensity on the calculated day of the year, and in the rest of the time, with the most demanded protection from solar radiation, the filter functions within acceptable limits. It is stated that the smart window with the built-in optical filter is most suitable for rooms with a long stay of people during daylight hours that is for office, educational, industrial, etc. rooms, in order to provide comfortable daylighting and the required insolation and thermal conditions during working hours.

scholarly journals Preparation and Properties of Thermoresponsive P(N-Isopropylacrylamide-co-butylacrylate) Hydrogel Materials for Smart Windows

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Jae-Hyung Park ◽  
Ji-Won Jang ◽  
Jae-Hak Sim ◽  
Il-Jin Kim ◽  
Dong-Jin Lee ◽  
...  
Keyword(s):  
Light Transmission ◽  
Crosslinking Agent ◽  
Three Dimensional ◽  
Light Transmittance ◽  
Solar Light ◽  
Solution Temperature ◽  
Smart Window ◽  
Thermoresponsive Polymers ◽  
Smart Windows ◽  
Hydrogel Films

Thermoresponsive polymers that exhibit phase transition in response to temperature change can be used as material for smart windows because they can control solar light transmission depending on the outside temperature. The development of thermoresponsive polymers for a smart window that can be used over a wide temperature range is required. Therefore, to obtain smart window materials that can be used at various temperatures, three-dimensional thermoresponsive P(NIPAm-co-BA) hydrogels were prepared by free radical polymerization from main monomer N-isopropylacrylamide, comonomer butyl acrylate, and crosslinking agent N,N′-methylenebisacrylamide (MBAm) in this study. This study examined the effect of BA content on the lower critical solution temperature (LCST) and the solar light transmittance of crosslinked P(NIPAm-co-BA) hydrogel films. The LCST of hydrogel films was found to be significantly decreased from 34.3 to 29.5°C with increasing BA content from 0 to 20 mol%. It was found that the transparent films at T=25°C (T<LCST) were converted to translucent films at a higher temperature (T=45°C) (T>LCST). These results suggested that the crosslinked P(NIPAm-co-BA) hydrogel materials prepared in this study could have high potential for application in smart window materials.

ATMOSPHERIC REFRACTION AND TEMPERATURE GRADIENT

1962 ◽  
Vol 16 (1) ◽  
pp. 24-31 ◽  
Author(s):  
P.V. Angus-Leppan
Keyword(s):  
Temperature Gradient ◽  
Solar Radiation ◽  
Radiation Intensity ◽  
Time Of Day ◽  
Vertical Temperature Gradient ◽  
Vertical Temperature ◽  
Atmospheric Refraction ◽  
Intensity Measurements ◽  
Solar Radiation Intensity

The coefficient of refraction is far from constant. It varies chiefly because of changes in the vertical temperature gradient of the atmosphere. From measurements of vertical angles between points of known heights, observed angles of refraction can be deduced. By the use of simultaneous meteorological measurements, various methods of calculating refraction are developed. It is necessary to derive a formula representing temperature as a function of height and time of day. Calculated refraction compares accurately with observed, especially when solar radiation intensity measurements are used.

scholarly journals Smart Window Based on Angular-Selective Absorption of Solar Radiation with Guest–Host Liquid Crystals

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 131
Author(s):  
Seong-Min Ji ◽  
Seung-Won Oh ◽  
Tae-Hoon Yoon
Keyword(s):  
Liquid Crystal ◽  
Energy Consumption ◽  
Liquid Crystals ◽  
Solar Radiation ◽  
Applied Voltage ◽  
Incident Light ◽  
Selective Absorption ◽  
Smart Window ◽  
Direct Sunlight ◽  
Smart Windows

In this study, we analyzed angular-selective absorption in a guest–host liquid crystal (GHLC) cell for its application in smart windows. For reducing the energy consumption, angular-selective absorption is desired because the light transmitted through windows during the daytime is predominantly incident obliquely from direct sunlight. Owing to the absorption anisotropy of guest dichroic dyes, a GHLC cell can absorb the obliquely incident light, while allowing people to see through windows in a normal view. Therefore, the cell can provide a comfortable environment for occupants, and reduce the energy required for cooling by blocking the solar heat incident from the oblique direction. The GHLC cell can be switched between the transparent and opaque states for a normal view. The rising (falling) time was 6.1 (80.5) ms when the applied voltage was 10 V.

scholarly journals Design, Fabrication, and Characterization of Thermal and Optical Properties of Nano-Composite Self-Cleaning Smart Window

2021 ◽  
Author(s):  
Mehdi Jafari Vardanjani ◽  
Mehdi Karevan
Keyword(s):  
Optical Properties ◽  
Energy Consumption ◽  
Light Transmission ◽  
Smart Window ◽  
Smart Windows ◽  
Smart Glasses ◽  
Present Design ◽  
Injection Mechanism ◽  
Fabrication And Characterization

Abstract Polymer-based smart windows have recently received attention due to their capabilities in energy consumption reduction. A smart window provides desired optical properties when heated/cooled by using solar energy when the ambient temperature requires regulation. The main issue here is the design and fabrication of such a smart element which is the main axis of the current research. The window in the proposed design operates in such a way that the percentage of light transmission depends on the presence of nanofluid between the two walls and refractive index conformity between the fluid and the polymeric walls; Therefore the percentage of light transmission will be at its minimum value (45%) in the absence of fluid and it will be at the maximum value (80%) at the presence of fluid. The fundamental steps of the present design includes design, fabrication, and characterization of the materials. In this regard experiments to determine the mechanical, physical, structural, optical, and thermal properties of components have been performed after considering, designing, and manufacturing various samples. The results show that the proposed smart offers acceptable performance with a fast switching rate and even more than other similar smart glasses due to the usage of discharge/injection mechanism. In overall, the product can be used as a smart transparent element in various structures such as buildings and even vehicles to regulate energy consumption and/or block the view for security purposes.

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