Sisteme de orientare a convertoarelor solare/Tracking systems for solar energy convertorsSisteme de orientare a convertoarelor solare/Tracking systems for solar energy convertors

Prof.dr.eng. Mircea Neagoe

03. Solar radiation

Radiaia extraterestr (B0) se mparte, prin traversarea stratului atmosferic, n radiaie solar direct (B) i radiaie solar difuz (D), cele dou componente formnd radiaia global (G).

Modeling the beam solar radiation B [W/m2]Modeling the beam solar radiation B [W/m2]

+=

sin4.99.0exp Ro

TBB

= cos* BB

( )[ ]ooo NB 72.29856.0cos0334.011367 +=

33/16/16

Extraterrestrial solar radiation

Available beam solar radiation (clear sky)

Received beam solar radiation

where: n day number of the year; TR beam radiation loss factor; incidence angle;

Braov (TR 3)Braov (TR 3) incidence angle incidence angle

*sinsin*)cos(coscoscos * +==eqPVsr ee

Radiaia solar direct este maxim (Bmax = B) pe direcia razei solare

CCR FBB =Available beam solar radiation (cloudy sky)

cos* = RR BB

Fcc_Braov valori Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

obinute experimental 0.28 0.27 0.36 0.36 0.38 0.44 0.48 0.455 0.44 0.45 0.4 0.29

+=

sin4.99.0exp Ro

TBB

= cos* BB

Available beam solar radiation (clear sky)

Received beam solar radiationCCR FBB =

Available beam solar radiation (clear sky)

Received beam solar radiation (Legea lui Lambert)

Modeling the diffuse solar radiation D [W/m2]Modeling the diffuse solar radiation D [W/m2]

44/16/16Radiaia solar difuz este maxim (Dmax = DH) n plan orizontal

CD_Braov valori Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

obinute experimental 0.21 0.26 0.27 0.26 0.28 0.27 0.28 0.27 0.27 0.27 0.25 0.18

recomandate n calcul 0.22 0.27 0.27 0.27 0.27 0.27 0.27 0.27 0.27 0.27 0.27 0.27

Expresiile radiaiei difuze disponibile i captate ntr-un plan orizontal HD , n cazul celor patru sisteme de orientare, n premisa cerului real estimat (Fcc < 1):

DISPONIBIL: CAPTAT :

ECUATORIAL ( ) sinsincoscoscos)( 0 += RD BBC ( )*****0 sinsincoscoscos)( += RD BBC PSEUDO

ECUATORIAL coscos)( 0 = RD BBC **0 coscos)( = RD BBC AZIMUTAL sin)( 0 RD BBC = *0 sin)( RD BBC = PSEUDO-

AZIMUTAL coscos)( 0 = RD BBC **0 coscos)( = RD BBC

Expresiile radiaiei difuze disponibile i captate ntr-un plan oarecare XD , n cazul celor patru sisteme de orientare,:

DISPONIBIL: CAPTAT :

ECUATORIAL ( )

2sinsincoscoscos1 ++

= HD ( )

2sinsincoscoscos1 ***** ++

= HD

PSEUDO ECUATORIAL 2

coscos1 += HD 2

coscos1 ** += HD

AZIMUTAL 2sin1 +

= HD 2sin1 *+

= HD

PSEUDO-AZIMUTAL 2

coscos1 += HD 2

coscos1 ** += HD

Modeling the global solar radiation G [W/m2]Modeling the global solar radiation G [W/m2]

55/16/16

+= tan

21tan 1

H

HG B

D( ) ( )2sin1

sincos)*(max GHGHXXGX

DBDBGG

++

=+===

Available global solar radiation

Received global solar radiation

+=

+=

XXX

HHH

DBGDBG

+=

+=

XXX

HHH

DBGDBG

***

***

Available MAXUMUM global solar radiation Gmax

Received direct solar radiation family for tracking steps analysis: the case of a pseudo-equatorial tracker during the SS in Bv/Ro

Variations of the received direct solar radiation: a the available radiation; a0 for a tilted fixed panel (*= 0) ; b for panel with *=67; c for *=63 ; d for

*=53 ; e for *=40 ; f for *=32; g for *=22 .

Eficiena de captare a radiaie solare

B, D, G [%] Eficiena de captare a radiaie solare directe (B), difuze (D), respectiv globale (G), descris ca mrime medie i ca mrime instantanee;

eficiena instantanee de captare este raportul ntre radiaia solar receptat pe suprafaa convertorului solar (B*, D*, respectiv G*) i radiaia solar disponibil (B, D,respectiv G).

eficiena medie de captare este raportul ntre energia radiaiei directe captate de suprafaa convertorului solar (E(B*), E(D*), respectiv E(G*)) i energia radiaiei solare disponibile (E(B), E(D), respectiv E(G)).

;*;*;*

maxGG

DD

BB

BH

DB ===

;)(*)(;)(

*)(;)(*)(

max

___ GEGE

DEDE

BEBE

medBH

medDmedB ===

References:References:

1.1. GoswamiGoswami, D.J., , D.J., KreithKreith, K., , K., KreiderKreider, J.F.: Principles of Solar Engineering,, J.F.: Principles of Solar Engineering,Philadelphia, PA, George H. Buchanan Co., 1999. Philadelphia, PA, George H. Buchanan Co., 1999.

2.2. Messenger, R., Messenger, R., VentreVentre, J.: Photovoltaic System Engineering, Boca Raton,, J.: Photovoltaic System Engineering, Boca Raton,London, New York, Washington, CRC Press, 2000.London, New York, Washington, CRC Press, 2000.

3.3. Stine, B.W., Stine, B.W., HarriganHarrigan, R.W.: Solar Energy Fundamentals and Design, , R.W.: Solar Energy Fundamentals and Design, West Sussex, USA, John Wiley & Sons, 1985.West Sussex, USA, John Wiley & Sons, 1985.

4.4. ***, Catalogue: Planning and Installing solar thermal systems, L***, Catalogue: Planning and Installing solar thermal systems, London, ondon, James & James, James & James, EarthscanEarthscan, 2005, 2005

5.5. DIACONESCU, D., VISA, I., BURDUHOS, B., DINICU (POPA), V.: DIACONESCU, D., VISA, I., BURDUHOS, B., DINICU (POPA), V.: Analysis of the SunAnalysis of the Sun--Earth angles used in the design of the solar Earth angles used in the design of the solar collectors' trackers, Bulletin of the Transilvania University ofcollectors' trackers, Bulletin of the Transilvania University of Brasov, Brasov, Vol.13(48), 2006, ISSN 1223 Vol.13(48), 2006, ISSN 1223 9631, pg. 999631, pg. 99--104.104.

6.6. VISA, I., DIACONESCU, D., DINICU (POPA), V., BURDUHOS, B.: VISA, I., DIACONESCU, D., DINICU (POPA), V., BURDUHOS, B.: On the Incidence Angle Optimization of the DualOn the Incidence Angle Optimization of the Dual--Axis Solar Trackers, Axis Solar Trackers, 11th International Research/Expert Conference TMT 11th International Research/Expert Conference TMT -- Trends in the Trends in the Development of Machinery and Associated TechnologyDevelopment of Machinery and Associated Technology, , HamammetHamammet, , Tunisia, 05Tunisia, 05--09 09 septembrieseptembrie 2007, ISBN 9958617342007, ISBN 995861734--X, pg. 1111X, pg. 1111--1114.1114.