CN113567374B - Method for calculating solar energy coefficient of heat gain of photochromic glass - Google Patents
Method for calculating solar energy coefficient of heat gain of photochromic glass Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/55—Specular reflectivity
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/59—Transmissivity
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/55—Specular reflectivity
- G01N2021/558—Measuring reflectivity and transmission
Abstract
The invention relates to a method for calculating solar energy coefficient of photochromic glass, which is characterized in that a transmittance-time curve of the darkening process and a transmittance-time curve of the light-time curve are obtained through testing the darkening process and the light-time curve of the light-time curve are obtained through testing, sunlight range spectrums of the darkening end time and the light-time curve are obtained through testing, and solar energy coefficient of the darkening end time and the light-time curve of the light-time curve are calculated according to solar transmittance and reflectance. The solar energy coefficient of heat gain can be well applied to evaluate the energy consumption performance of the photochromic glass in the actual building, and is convenient for the engineering application and popularization of the photochromic glass.
Description
Technical Field
The invention relates to a method for calculating solar energy coefficient of photochromic glass, in particular to a calculation flow and a method for calculating solar energy coefficient of photochromic glass, which can be used for energy consumption calculation.
Background
The photochromic glass, namely the photochromic glass for short, can be colored after light irradiation, and can be restored to the original state after the light irradiation is stopped for a period of time. The light transmittance of the solar energy collector can be changed along with the change of the radiation light intensity, so that the solar energy collector can control the sunlight to enter, so that the indoor environment always has proper brightness and temperature, the use of an air conditioner is effectively reduced, and the energy reduction and consumption reduction of a building are realized.
The solar heat gain coefficient is also called solar total transmittance, and refers to the ratio of the amount of heat obtained in a solar radiation chamber passing through the light-transmitting envelope to the amount of solar radiation projected onto the outer surface of the light-transmitting envelope, is a key index for evaluating the energy consumption performance of the light-transmitting envelope such as glass in a building, and is an important parameter for guiding the research and development of color-changing glass materials.
However, since the solar transmittance of the photochromic glass is changed from time to time under the action of illumination, a method for calculating the solar heat gain coefficient of the photochromic glass in the actual environment is lacking, so that the energy-saving performance of the photochromic glass in the building cannot be evaluated, and the photochromic glass with which performance is suitable for being installed in different types of buildings cannot be accurately determined. This undoubtedly hinders the progress of mass production of the photochromic glass, and greatly limits the application and popularization of the photochromic glass in actual buildings.
Disclosure of Invention
In view of the shortcomings of the prior art, the invention aims to provide a method for calculating the solar energy coefficient of the photochromic glass, which is simple and practical and is convenient for application and popularization of the photochromic glass in actual buildings.
In order to achieve the above object, the present invention provides a method for calculating solar heat gain coefficient of photochromic glass, comprising the following steps:
1) The method comprises the steps that light rays with certain test light intensity are emitted by an excitation light source in a darkroom to continuously irradiate the photochromic glass from an initial time to a time t1, wherein the time t1 is a darkening end time, and the initial time to the time t1 is the darkening time of the photochromic glass; continuously detecting visible light transmittance of the photochromic glass by using a transmittance detector from the initial time to the time t1, so as to obtain a transmittance-time curve of the darkening process of the photochromic glass;
2) Turning off the excitation light source at the time t1, performing a test of the reproduction process to the time t2, wherein the time t2 is the reproduction end time, and the time t1 to the time t2 is the photochromic glass reproduction duration; continuously detecting the visible light transmittance of the photochromic glass by using a transmittance detector during the time from the time t1 to the time t2, so as to obtain a transmittance-time curve of the photochromic glass in the process of recovering the light;
3) Test of transmittance and reflectance of photochromic glass at the end of darkening:
3a) Standing the photochromic glass in a darkroom to completely restore the sample to an initial state; the excitation light source is utilized to emit the light with certain test light intensity to continuously irradiate the photochromic glass for a dimming time, and then the light is immediately transferred to a spectrophotometer for testing to obtain the transmittance of the photochromic glass in the sunlight spectrum range;
3b) Standing the photochromic glass in a darkroom to enable the sample to completely recover to an initial state, and immediately transferring the photochromic glass to a spectrophotometer for testing after the excitation light source is reused to emit light with certain test light intensity to continuously irradiate the photochromic glass for a dimming period of time so as to obtain the reflectance of the photochromic glass in the sunlight spectrum range;
4) Test of transmittance and reflectance of photochromic glass at the end of the review:
4a) Standing the photochromic glass in a darkroom to completely restore the sample to an initial state; the excitation light source is utilized to emit the light with certain test light intensity to continuously irradiate the photochromic glass for a dimming duration, then the photochromic glass is kept away from light and is kept stand for a dimming duration, and then the photochromic glass is immediately transferred to a spectrophotometer for testing, so that the transmittance of the photochromic glass in the sunlight spectrum range is obtained;
4b) Standing the photochromic glass in a darkroom to completely restore the sample to an initial state; the excitation light source is utilized to emit the light with certain test light intensity to continuously irradiate the photochromic glass for a dimming duration, then the photochromic glass is kept away from light and is kept stand for a dimming duration, and then the photochromic glass is immediately transferred to a spectrophotometer for testing, so that the reflectance of the photochromic glass in the sunlight spectrum range is obtained;
5) And calculating the solar heat gain coefficient SHGC1 at the dimming end time according to the transmittance and reflectance data of the photochromic glass at the dimming end time, and calculating the solar heat gain coefficient SHGC2 at the dimming end time according to the transmittance and reflectance data of the photochromic glass at the dimming end time.
Preferably, the steps 1) to 4) are performed in a dark room at a temperature of 20 ℃.
Preferably, the light intensity of the excitation light source is 5-10 kaleidos.
More preferably, the light source is a xenon arc lamp.
Preferably, in the step 1), the time t1 is a time when the transmittance change rate on the transmittance-time curve of the dimming process is reduced to less than 0.5.
Preferably, in step 3) and step 4), the light wavelength range of the solar spectral range is selected to be 200nm to 2500nm.
Preferably, in the step 2), the end time t2=t1+n·t1 of the restoration is performed
Wherein the value of N is determined as follows:
counting the solar radiation intensity distribution in a set period of time of the photochromic glass target usage place; counting the time period with sunlight irradiation as a-b; counting the time periods a-b, wherein the solar radiation intensity is 0 and the number of hours greater than the test light intensity is N 1 、N 2 Then n=n 1 /N 2 。
More preferably, the set period is based on a solar radiation intensity month average value of about 10 years, and a year of which the solar radiation intensity is close to the solar radiation intensity month average value of about 10 years is selected from solar radiation intensity data of about 10 years as the set period.
Preferably, in the step 5), the solar heat gain coefficient calculation formula is
Wherein:
g is the solar radiation absorption coefficient of the non-light-transmitting part in the door and window and curtain wall, and has no dimension;
A g the area of the light-transmitting part in the door and window and curtain wall;
ρ is the solar absorption ratio of the opaque portion;
k is the heat transfer coefficient of the non-light-transmitting part in the door and window and curtain wall;
α e the heat convection coefficient of the outer surface;
A f the area of the non-light-transmitting part in the door, window and curtain wall;
A w the area of the door and window and curtain wall;
the algorithm of g is calculated according to the regulations of the national standard 'determination of visible light transmittance, sunlight direct transmittance, solar total transmittance, ultraviolet transmittance and related window glass parameters' GB/T2680.
As described above, the method for calculating the solar energy coefficient of the photochromic glass has the following beneficial effects: in the method for calculating the solar energy coefficient of the photochromic glass, according to the test of the darkening process and the re-lighting process of the photochromic glass, the transmittance-time curve of the darkening process and the transmittance-time curve of the re-lighting process of the photochromic glass sample are obtained, the transmittance and the reflectance of the darkening end time and the re-lighting end time in the sunlight spectrum range are respectively obtained through the test, and the solar energy coefficient of the photochromic glass at the darkening end time and the re-lighting end time is calculated according to the transmittance and reflectance data of the photochromic glass at the darkening end time and the re-lighting end time. The solar energy coefficient of heat gain can be well applied to evaluate the energy consumption performance of the photochromic glass in the actual building, and is convenient for the engineering application and popularization of the photochromic glass.
Drawings
Fig. 1 shows darkening and light recovery curves for two photochromic glasses.
Fig. 2 shows a solar radiation intensity distribution diagram of 8760 hours throughout the year for a city.
Fig. 3 shows a statistical plot of solar radiation intensity for a city.
Fig. 4 shows a graph of energy consumption rate calculations for office buildings and libraries.
Detailed Description
Further advantages and effects of the present invention will become apparent to those skilled in the art from the disclosure of the present invention, which is described by the following specific examples.
It should be understood that the structures, proportions, sizes, etc. shown in the drawings are for illustration purposes only and should not be construed as limiting the invention to the extent that it can be practiced, since modifications, changes in the proportions, or otherwise, used in the practice of the invention, are not intended to be critical to the essential characteristics of the invention, but are intended to fall within the spirit and scope of the invention. Also, the terms such as "upper," "lower," "left," "right," "middle," and "a" and the like recited in the present specification are merely for descriptive purposes and are not intended to limit the scope of the invention, but are intended to provide relative positional changes or modifications without materially altering the technical context in which the invention may be practiced.
Referring to fig. 1, the present invention provides a method for calculating solar heat gain coefficient of photochromic glass, comprising the following steps:
1) Continuously radiating the photochromic glass from an initial time (0) to a time t1 by utilizing light rays with certain test light intensity emitted by an excitation light source in a darkroom, wherein the time t1 is a darkening end time, and the initial time to the time t1 are darkening time of the photochromic glass; continuously detecting visible light transmittance of the photochromic glass by using a transmittance detector from the initial time to the time t1, so as to obtain a transmittance-time curve of the darkening process of the photochromic glass;
2) Turning off the excitation light source at the time t1, performing a test of the reproduction process to the time t2, wherein the time t2 is the reproduction end time, and the time t1 to the time t2 is the photochromic glass reproduction duration; continuously detecting the visible light transmittance of the photochromic glass by using a transmittance detector during the time from the time t1 to the time t2, so as to obtain a transmittance-time curve of the photochromic glass in the process of recovering the light;
3) Test of transmittance and reflectance of photochromic glass at the end of darkening:
3a) Standing the photochromic glass in a darkroom to completely restore the sample to an initial state; the excitation light source is utilized to emit the light with certain test light intensity to continuously irradiate the photochromic glass for a dimming time, and then the light is immediately transferred to a spectrophotometer for testing to obtain the transmittance of the photochromic glass in the sunlight spectrum range;
3b) Standing the photochromic glass in a darkroom to enable the sample to completely recover to an initial state, and immediately transferring the photochromic glass to a spectrophotometer for testing after the excitation light source is reused to emit light with certain test light intensity to continuously irradiate the photochromic glass for a dimming period of time so as to obtain the reflectance of the photochromic glass in the sunlight spectrum range;
4) Test of transmittance and reflectance of photochromic glass at the end of the review:
4a) Standing the photochromic glass in a darkroom to completely restore the sample to an initial state; the excitation light source is utilized to emit the light with certain test light intensity to continuously irradiate the photochromic glass for a dimming duration, then the photochromic glass is kept away from light and is kept stand for a dimming duration, and then the photochromic glass is immediately transferred to a spectrophotometer for testing, so that the transmittance of the photochromic glass in the sunlight spectrum range is obtained;
4b) Standing the photochromic glass in a darkroom to completely restore the sample to an initial state; the excitation light source is utilized to emit the light with certain test light intensity to continuously irradiate the photochromic glass for a dimming duration, then the photochromic glass is kept away from light and is kept stand for a dimming duration, and then the photochromic glass is immediately transferred to a spectrophotometer for testing, so that the reflectance of the photochromic glass in the sunlight spectrum range is obtained;
5) And calculating the solar heat gain coefficient SHGC1 at the dimming end time according to the transmittance and reflectance data of the photochromic glass at the dimming end time, and calculating the solar heat gain coefficient SHGC2 at the dimming end time according to the transmittance and reflectance data of the photochromic glass at the dimming end time.
In the method for calculating the solar energy coefficient of the photochromic glass, according to the test of the darkening process and the re-lighting process of the photochromic glass, the transmittance-time curve of the darkening process and the transmittance-time curve of the re-lighting process of the photochromic glass sample are obtained, the transmittance and the reflectance of the darkening end time and the re-lighting end time in the sunlight spectrum range are respectively obtained through the test, and the solar energy coefficient of the photochromic glass at the darkening end time and the re-lighting end time is calculated according to the transmittance and reflectance data of the photochromic glass at the darkening end time and the re-lighting end time. The solar energy coefficient of heat gain can be well applied to evaluate the energy consumption performance of the photochromic glass in the actual building, and is convenient for the engineering application and popularization of the photochromic glass.
According to the method for calculating the solar energy coefficient of the photochromic glass, the duration of the darkening process and the re-lighting process of the photochromic glass is determined through testing; obtaining a transmittance-time curve of a darkening process and a transmittance-time curve of a light restoration process of the photochromic glass under a stable environment and a light source; measuring solar light range transmittance and reflectance at the end of the darkening process (time t 1) and at the end of the light recovery process (time t 2); and calculating the solar energy coefficient under two moments by using a formula. The method is simple and practical, and is convenient for application and popularization of the photochromic glass in actual buildings.
In order to make the test data accurate and stable and reduce errors caused by environmental influences, the steps 1) to 4) are completed in a darkroom with the temperature of 20 ℃. The "darkroom" is a special dark darkroom environment space used for optical test and is common knowledge of the person skilled in the art.
As a preferred embodiment, in the step 1), the photochromic glass sample is continuously irradiated with an excitation light source having a light intensity of 5 to 10 kaleidos when testing the transmittance-time curve of the darkening process; the light source is turned off when the transmittance-time curve of the recovery process is tested. The light source can be a xenon arc lamp or the like. The transmittance-time curve of the darkening process is a curve of the transmittance of the photochromic glass which changes with time when the light source is continuously irradiated; the transmittance-time curve of the light recovery process is a curve of the transmittance of the photochromic glass over time when the light source is turned off.
After darkening of the photochromic glass to a certain extent, the extent to which it continues to darken is very small and very slow, and as a preferred embodiment, in said step 1), the time t1 is the time at which the transmittance change rate on the transmittance-time curve of the darkening process falls below 0.5, the transmittance change rate being the tangential slope (or derivative value dy/dt thereof) at any point on the transmittance-time curve. Considering practical applications, the darkening of the photochromic glass is negligible after the transmittance change rate drops below 0.5.
As a preferred embodiment, in the step 3) and the step 4), the solar light with more than 98% energy in the range of 200-2500 nm is considered, and for the sake of simple test, the light wavelength range of the solar light spectrum range is selected to be 200-2500 nm, so that the method is more suitable for engineering practice conditions. The calculation formulas of the solar heat gain coefficients SHGC1 and SHGC2 are the calculation formulas of the solar heat gain coefficients of the conventional glass specified by national standard specifications. In the step 5), the calculation formula of the solar energy coefficient of heat gain is as follows
Wherein:
g is the solar radiation absorption coefficient of the non-light-transmitting part in the door and window and curtain wall, and has no dimension;
A g the area of the light-transmitting part in the door and window and curtain wall;
ρ is the solar absorption ratio of the opaque portion;
k is the heat transfer coefficient of the non-light-transmitting part in the door and window and curtain wall;
α e the heat convection coefficient of the outer surface;
A f the area of the non-light-transmitting part in the door, window and curtain wall;
A w the area of the door and window and curtain wall;
the algorithm of g is calculated according to the regulations of the current national standard 'determination of visible light transmittance, sunlight direct transmittance, solar total transmittance, ultraviolet transmittance and related window glass parameters' GB/T2680, namely:
g＝τ e +q i
τ e the direct transmittance of sunlight of the sample,
q i the secondary heat transfer coefficient to the indoor side,
ρ e the direct reflectance of sunlight of the sample,
α e -sunlight direct absorption ratio of sample, alpha e ＝1-τ e -ρ e
h i -inner surface heat transfer coefficient, h i ＝8W/m 2 ·K
h e -external surface heat transfer coefficient, h e ＝23W/m 2 ·K
Wherein the method comprises the steps of
E (lambda) -relative spectral distribution of solar radiation
Deltalambda-wavelength interval in nm
τ (λ) -solar spectral transmittance of sample
ρ (λ) -the solar spectral transmittance of the sample.
In order to facilitate engineering practice application and popularization, the light glass recovery time t2 can be determined as follows:
in the step 2), the end time t2=t1+n·t1 of the recovery process is calculated
Wherein the value of N is determined as follows:
counting the solar radiation intensity distribution in a set period of time of the photochromic glass target usage place; counting the time period with sunlight irradiation as a-b; counting the time periods a-b, wherein the solar radiation intensity is 0 and the number of hours greater than the test light intensity is N 1 、N 2 Then n=n 1 /N 2 . The set period is based on a solar radiation intensity month average value of about 10 years, and a year with solar radiation intensity close to the solar radiation intensity month average value of about 10 years is selected from solar radiation intensity data of about 10 years to serve as the set period.
The "set period" involved in the aforementioned "statistics of solar radiation intensity distribution within set period of use of photochromic glass target" may be selected as required, and as a preferred embodiment, the set period may be selected as a typical meteorological year of use of photochromic glass target, statistics of solar radiation intensity distribution within 8760 hours of typical meteorological year; counting the time period with sunlight irradiation as a-b; in the period a-b, the solar radiation intensity is 0 and the number of hours greater than the test light intensity is N1 and N2 respectively in 8760 hours of the whole year, and then N=N1/N2. The typical weather year is based on a solar radiation intensity month average value of about 10 years, and a year with solar radiation intensity close to the solar radiation intensity month average value of about 10 years is selected from solar radiation intensity data of about 10 years as the typical weather year.
The method for testing transmittance and reflectance of photochromic glass is described in "test method for measuring solar transmittance and solar absorption ratio of materials by a spectrophotometer in GB T25968-2010" and other documents, and is common knowledge in the art, and will not be described in detail herein.
According to the method for calculating the solar energy coefficient of the photochromic glass, according to the transmittance-time curve of the darkening and the re-lighting process of the photochromic glass, the photochromic glass gradually changes color to saturated transmittance when the transmittance is larger than the radiation intensity; at a radiation of 0, the initial transmittance will be gradually restored. Considering the solar irradiation characteristics in a typical day, the lowest transmittance that can be achieved by the photochromic glass is the saturation transmittance, and the highest transmittance is the recovery transmittance that can be achieved for a recovery period. Thus, the solar heat gain coefficient of the photochromic glass is a range interval of solar heat gain coefficients at the end of the darkening process and at the end of the restoration process. The solar transmittance and reflectance at the two moments are measured, and the SHGC1 and the SHGC2 are calculated by using a formula, namely the solar heat gain coefficient range of the photochromic glass. The value can be well applied to evaluate the energy consumption performance of the photochromic glass in actual buildings.
The following describes a method for calculating solar heat gain coefficient of photochromic glass according to the present invention by using an application case.
Fig. 2 is a graph of the direct solar radiation profile obtained by energy consumption simulation software for 8760 hours in a model year. FIG. 3 is a graph showing the statistics of the radiation intensity of 0 and more than 10 Wallows illuminance (in units of irradiation intensity W/m 2 By 683) the number of hours of light intensity. According to statistics, the ratio of the number of hours with irradiation greater than 10 k-grams and 0 is about 1:1.5. Fig. 1 is a transmittance-time curve for the darkening process and a transmittance-time curve for the lightening process for two photochromic glasses tested, the test equipment comprising a xenon arc lamp, a transmittance test equipment and a record storage system. In a darkroom, a darkening process test is carried out by using 10-kaleidos light intensity, a light is turned off when the transmittance change rate is lower than 0.5, a light shielding process test is carried out, the irradiation mode is vertical irradiation, and the test temperature is constant at 20 ℃. As can be seen from fig. 1, when irradiated for 5 minutes, the transmittance change rate of the photochromic glass is lower than 0.5, i.e., the darkening process is 0 to 5 minutes. According to the method for calculating the recovery time length, the recovery process is 5-5+1.5x5 minutesAnd (3) a clock. The solar transmission spectra of the photochromic glass were measured at a time of 5 minutes and a time of 12.5 minutes, respectively. According to the formula in the civil architecture thermal design Specification (GB 50176), the solar energy coefficient of heat gain ranges of the low-transmittance and high-transmittance photochromic solar energy are respectively 0.569-0.680 and 0.732-0.799. And according to the coefficient value, building energy consumption checking calculation is carried out.
A typical city in a summer hot winter warm area is selected as a simulation place, and the weather parameters are respectively the typical weather years of the city. Building models of office buildings and libraries, setting indoor heat interference and air conditioner start-stop work and rest work as office staff/equipment/lamplight work and rest work, and setting proper room temperature ranges in different months slightly different. The window wall ratio of the office building and the library is 0.25 and 0.60 in sequence, the materials and parameters of the non-transparent enclosure structure are software default values, and the specific parameters are shown in table 1.
TABLE 1 thermal parameters of building envelope
Fig. 4 shows a graph of energy consumption rate calculations for office buildings and libraries. In office buildings and libraries, the total annual energy consumption of the low-transmittance photochromic glass is 98-98% and 91-94% of the total energy consumption of common glass in turn; the high-transmittance photochromic glass is 99-99% and 96-99% in turn, and compared with common glass, both the photochromic glass has certain energy-saving effect. The solar energy coefficient calculated by the method is used for actual energy consumption calculation, the energy consumption rate is in the range of 0-3%, the fluctuation range is small, and the method has a certain practical significance for the energy consumption estimation of the photochromic glass with dynamic change in the actual engineering.
Based on the description of the technical scheme, the invention aims to provide a method for calculating the solar energy coefficient of the photochromic glass, which solves the problems that the solar light transmittance of the existing photochromic glass is changed at moment and the energy consumption performance of the existing photochromic glass is difficult to evaluate, and establishes the method for calculating the solar energy coefficient of the photochromic glass through analysis of solar radiation and glass color change characteristics.
In summary, the present invention effectively overcomes the disadvantages of the prior art and has high industrial utility value.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.
Claims (7)
1. A method for calculating solar heat gain coefficient of photochromic glass, comprising the steps of:
1) The method comprises the steps that light rays with certain test light intensity are emitted by an excitation light source in a darkroom to continuously irradiate the photochromic glass from an initial time to a time t1, wherein the time t1 is a darkening end time, and the initial time to the time t1 is the darkening time of the photochromic glass; continuously detecting visible light transmittance of the photochromic glass by using a transmittance detector from the initial time to the time t1, so as to obtain a transmittance-time curve of the darkening process of the photochromic glass;
2) Turning off the excitation light source at the time t1, performing a test of the reproduction process to the time t2, wherein the time t2 is the reproduction end time, and the time t1 to the time t2 is the photochromic glass reproduction duration; continuously detecting the visible light transmittance of the photochromic glass by using a transmittance detector during the time from the time t1 to the time t2, so as to obtain a transmittance-time curve of the photochromic glass in the process of recovering the light; end time t2=t1+n·t1 at the time of the return
Wherein the value of N is determined as follows:
counting the solar radiation intensity distribution in a set period of time of the photochromic glass target usage place; counting the time period with sunlight irradiation as a-b; in the time interval a-b, the solar radiation intensity is 0, and the number of hours greater than the test light intensity is N1 and N2 respectively, wherein N=N1/N2;
the set time period is based on a solar radiation intensity month average value of about 10 years, and a year of which the solar radiation intensity is close to the solar radiation intensity month average value of about 10 years is selected from solar radiation intensity data of about 10 years to serve as the set time period;
3) Test of transmittance and reflectance of photochromic glass at the end of darkening:
3a) Standing the photochromic glass in a darkroom to completely restore the sample to an initial state; the excitation light source is utilized to emit the light with certain test light intensity to continuously irradiate the photochromic glass for a dimming time, and then the light is immediately transferred to a spectrophotometer for testing to obtain the transmittance of the photochromic glass in the sunlight spectrum range;
3b) Standing the photochromic glass in a darkroom to enable the sample to completely recover to an initial state, and immediately transferring the photochromic glass to a spectrophotometer for testing after the excitation light source is reused to emit light with certain test light intensity to continuously irradiate the photochromic glass for a dimming period of time so as to obtain the reflectance of the photochromic glass in the sunlight spectrum range;
4) Test of transmittance and reflectance of photochromic glass at the end of the review:
4a) Standing the photochromic glass in a darkroom to completely restore the sample to an initial state; the excitation light source is utilized to emit the light with certain test light intensity to continuously irradiate the photochromic glass for a dimming duration, then the photochromic glass is kept away from light and is kept stand for a dimming duration, and then the photochromic glass is immediately transferred to a spectrophotometer for testing, so that the transmittance of the photochromic glass in the sunlight spectrum range is obtained;
4b) Standing the photochromic glass in a darkroom to completely restore the sample to an initial state; the excitation light source is utilized to emit the light with certain test light intensity to continuously irradiate the photochromic glass for a dimming duration, then the photochromic glass is kept away from light and is kept stand for a dimming duration, and then the photochromic glass is immediately transferred to a spectrophotometer for testing, so that the reflectance of the photochromic glass in the sunlight spectrum range is obtained;
5) Calculation of the darkening end time based on the photochromic glass transmittance and reflectance data at the darkening end timeSolar heat gain coefficient SHGC 1 Calculating the solar heat gain coefficient SHGC at the time of the end of the restoration according to the transmittance and reflectance data of the photochromic glass at the time of the end of the restoration 2 。
2. The method of calculating the solar heat gain coefficient of a photochromic glass of claim 1, wherein:
the steps 1) to 4) are completed in a darkroom with the temperature of 20 ℃.
3. The method of calculating the solar heat gain coefficient of a photochromic glass of claim 1, wherein:
the light intensity of the excitation light source is 5-10 kaleidos.
4. A method of calculating the solar heat gain coefficient of a photochromic glass according to claim 3, wherein: the light source is a xenon arc lamp.
5. The method of calculating the solar heat gain coefficient of a photochromic glass of claim 1, wherein:
in the step 1), the time t1 is the time when the transmittance change rate on the transmittance-time curve of the dimming process is reduced to less than 0.5.
6. The method of calculating the solar heat gain coefficient of a photochromic glass of claim 1, wherein:
in the step 3) and the step 4), the light wavelength range of the solar spectrum range is selected to be 200nm to 2500nm.
7. The method of calculating the solar heat gain coefficient of a photochromic glass of claim 1, wherein:
in the step 5), the calculation formula of the solar energy coefficient of heat gain is as follows
Wherein:
g is the solar radiation absorption coefficient of the non-light-transmitting part in the door and window and curtain wall, and has no dimension;
A g the area of the light-transmitting part in the door and window and curtain wall;
ρ is the solar absorption ratio of the opaque portion;
k is the heat transfer coefficient of the non-light-transmitting part in the door and window and curtain wall;
α e the heat convection coefficient of the outer surface;
A f the area of the non-light-transmitting part in the door, window and curtain wall;
A w the area of the door and window and curtain wall;
the algorithm of g is calculated according to the regulations of the national standard 'determination of visible light transmittance, sunlight direct transmittance, solar total transmittance, ultraviolet transmittance and related window glass parameters' GB/T2680.
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