Как выбрать гостиницу для кошек
14 декабря, 2021
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Application of the standards EN13363
The standard EN13363-2 gives a methodology to calculate the optical properties of slat devices, however with two deficiencies: it is assumed that no direct sun may penetrate the blinds. Therefore the range of incidence angles where the method can be applied, is limited and dependent on the tilt angle. Therefore we did not use that model but our own extended model. The heat transport in EN13363-2 is similar to ISO15099 and thus should produce results very close to the WIS program. We tested therefore only the simplified approach of the part 1, where the g-value of solar shading plus glazing is calculated from optical properties (transmittance and reflectance) of the shading device and the g — and U — value of the glazing.
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Table 2: Results for three different models (ISE, WIS, EN) for glazing Silverstar and |
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internal white blinds compared with experimental g-value (exp) |
Using this simplified method of the standard EN13363-1 ("model EN”) a third set of results can be produced and be compared to the data. The optical data for the blinds were the ones used in the ISE model. The EN-model always produced the most conservative data which is reasonable for a simplified standard method.
|
profile angle |
tilt angle |
exp |
ISE |
WIS |
EN |
|
0 |
0 |
0.43 |
0.42 |
0.51 |
0.49 |
|
45 |
0 |
0.10 |
0.12 |
0.15 |
0.14 |
|
60 |
0 |
0.07 |
0.07 |
0.12 |
0.08 |
|
0 |
45 |
0.15 |
0.19 |
0.18 |
0.21 |
|
45 |
45 |
0.04 |
0.05 |
0.06 |
0.05 |
|
Table 3: Results for three different models (ISE, WIS, EN) for glazing Silverstar and |
|
external white blinds compared with experimental g-value (exp) |
|
0.70 0.60 0.50 0.40 О a 0.30 0.20 0.10 |
|
0.00 |
|
-90 -60 -30 0 30 60 90 |
|
profile angle [deg] |
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Figure 9: Experimental data in comparison with WIS-model using flat slats and the ISE extended view factor model using curved slats; white integrated blinds with solar control glazing g=47%, tilt angles 0°, 45° and 70° |
Integrated solar shading
For integrated blinds no resistance model had been developed. Therefore for comparison we used the very simple approach of EN13363-1 for integrated blinds. It can be seen from Figure 9 that the maximum g-value is overpredicted although curved slats have been modelled. The problem is not the optical part but the thermal part of the model! The WIS calculation based on ISO15099 gives a reasonable approximation of the experimental data.
From the results one can conclude that the optical calculation model based on the standard are not adequate for the systems investigated as they all are restricted to flat slats, and do not allow situations with direct transmittance to be evaluated. This will be important however, when the transmittance from the ground reflection will be evaluated. To approximate a complex shape of a diffuse lamella with an equivalent curved lamella of same height seems to reproduce the experimental data quite well. Also the heat transport based on a surface coefficient resistance model seems to be adequate whereas the simplified approach of EN13363-1 overpredicts the total solar energy transmittance.