15.07.2015   EuroSun2008-2

Determination of Field Boundary Line

Solar rays reflected by heliostats at any location in the heliostat field should totally go into the receiver aperture. Therefore, the field boundary line should be determined by the condition that the facula reflected to receiver aperture by heliostat should be in the range of aperture.

Assume that, the receiver aperture plane is notated as Plane a, and the plane which is perpendicular to OiE and point E(0,0,Ht) is the foot of a perpendicular is notated as Plane bt. From the solar

ray divergence angle of 32′, which has been reported earlier [6], the facula on Plane bt reflected

Function of facula on Plane bi reflected by Heliostat i is deduced by formula (2) and (3),

■B|-VB.2 -4AC <y<-B, + ,/B,2 -4A, C,

 

2 A

 

2 A

 

z = Xx + УУ + H

 
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And

0.009308 I 2 2 ,, 2 0.009308 / 2 2 ,, 2

xє[———— 2— Vx, + У + Ht, +—2— + У + Ht ].

Put the facula on Plane bt into some area elements dsj ( (j=l,2,3,…is the elements’ number).

Assume that dsj is relatively small enough, and its coordinates is expressed as Sj (x]bi, y]bi, z]bi), so that:

 
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image055
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(6)

 

If the shape of receiver aperture is rectangle, it can be assumed that the height and width of receiver aperture are Lr and Wr respectively. When element ds1ai is in the range of receiver aperture, its coordinates need to satisfy the following condition.

 

-1W < x}. <1W

2 r a 2 r

L. , L.

-ysinaR < ya, <уsinaR

 

(7)

 

When all elements ds]ai are in the range of receiver aperture, Heliostat i is in the range of heliostat

field, otherwise Heliostat i is out of in the range of heliostat field. According by this, calculating and distinguishing all locations in a large area around the tower, field boundary line can be educed.

 

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