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אסיף מאגר המחקר החקלאי
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The effect of screen texture on air flow and radiation transmittance: Laboratory and field experiments
Year:
2014
Source of publication :
Acta Horticulturae
Authors :
Cohen, Shabtai
;
.
Pirkner, Moran
;
.
Shahak, Yosepha
;
.
Tanny, Josef
;
.
Teitel, Meir
;
.
Volume :
1015
Co-Authors:

Tanny, J., Agricultural Research Organization, Volcani Center, POB 6, Bet Dagan 50250, Israel
Pirkner, M., Agricultural Research Organization, Volcani Center, POB 6, Bet Dagan 50250, Israel
Teitel, M., Agricultural Research Organization, Volcani Center, POB 6, Bet Dagan 50250, Israel
Cohen, S., Agricultural Research Organization, Volcani Center, POB 6, Bet Dagan 50250, Israel
Shahak, Y., Agricultural Research Organization, Volcani Center, POB 6, Bet Dagan 50250, Israel
Shapira, O., Jordan Valley Banana, Experimental Station, Zemach 15132, Israel
Israeli, Y., Jordan Valley Banana, Experimental Station, Zemach 15132, Israel

 

Facilitators :
From page:
45
To page:
52
(
Total pages:
8
)
Abstract:
The area of cultivation under screen covers and in screenhouses is constantly increasing in the semi-arid regions of Israel, Morocco and other countries. Banana screenhouses are currently equipped with transparent shading screens, with a nominal shading of about 8-15%. Two types of screens are widely used, woven and knitted, which differ in their texture and hence in their radiative and aerodynamic properties. However, the market is abundant with a large variety of screens and farmers do not have sound criteria to choose the optimal one. The goal of the present research was to investigate two types of screens of the same nominal shading level, 10%, but different texture: woven and knitted. Wind tunnel experiments and radiation measurements on a roof of a building were done to study pressure drop and radiative properties of the screens, respectively. In a field study a large commercial banana plantation in Northern Israel was covered with patches of the different screen types. In the field, air velocity and global radiation were measured simultaneously below the two different screens. Wind tunnel results showed that over the range of upstream air velocities of 0.4-2.5 m s-1 the pressure drops on the knitted screen were 56% of the values measured with the woven one. Transmittance of the knitted screen sample to global radiation was 97% of the woven screen. In the field, under the knitted screen, horizontal mean air velocity and global radiation were on average larger by 18 and 7%, respectively, than those measured under the woven one. The change in radiation transmittance ratio between the two screens measured in the field as compared to the ratio measured on the roof was probably due to enhanced dust accumulations of the woven screen in the field.
Note:
Related Files :
Air velocity
banana
Radiation
screenhouse
shading
Show More
Related Content
More details
DOI :
Article number:
0
Affiliations:
Database:
Scopus
Publication Type:
article
;
.
Language:
English
Editors' remarks:
ID:
29967
Last updated date:
02/03/2022 17:27
Creation date:
17/04/2018 00:51
Scientific Publication
The effect of screen texture on air flow and radiation transmittance: Laboratory and field experiments
1015

Tanny, J., Agricultural Research Organization, Volcani Center, POB 6, Bet Dagan 50250, Israel
Pirkner, M., Agricultural Research Organization, Volcani Center, POB 6, Bet Dagan 50250, Israel
Teitel, M., Agricultural Research Organization, Volcani Center, POB 6, Bet Dagan 50250, Israel
Cohen, S., Agricultural Research Organization, Volcani Center, POB 6, Bet Dagan 50250, Israel
Shahak, Y., Agricultural Research Organization, Volcani Center, POB 6, Bet Dagan 50250, Israel
Shapira, O., Jordan Valley Banana, Experimental Station, Zemach 15132, Israel
Israeli, Y., Jordan Valley Banana, Experimental Station, Zemach 15132, Israel

 

The effect of screen texture on air flow and radiation transmittance: Laboratory and field experiments
The area of cultivation under screen covers and in screenhouses is constantly increasing in the semi-arid regions of Israel, Morocco and other countries. Banana screenhouses are currently equipped with transparent shading screens, with a nominal shading of about 8-15%. Two types of screens are widely used, woven and knitted, which differ in their texture and hence in their radiative and aerodynamic properties. However, the market is abundant with a large variety of screens and farmers do not have sound criteria to choose the optimal one. The goal of the present research was to investigate two types of screens of the same nominal shading level, 10%, but different texture: woven and knitted. Wind tunnel experiments and radiation measurements on a roof of a building were done to study pressure drop and radiative properties of the screens, respectively. In a field study a large commercial banana plantation in Northern Israel was covered with patches of the different screen types. In the field, air velocity and global radiation were measured simultaneously below the two different screens. Wind tunnel results showed that over the range of upstream air velocities of 0.4-2.5 m s-1 the pressure drops on the knitted screen were 56% of the values measured with the woven one. Transmittance of the knitted screen sample to global radiation was 97% of the woven screen. In the field, under the knitted screen, horizontal mean air velocity and global radiation were on average larger by 18 and 7%, respectively, than those measured under the woven one. The change in radiation transmittance ratio between the two screens measured in the field as compared to the ratio measured on the roof was probably due to enhanced dust accumulations of the woven screen in the field.
Scientific Publication
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