cap02-Sun and radiation

Architecture and solar energy Energy and environment

by Moisès Morató

Sun, earth and radiation


by Moisès Morató

R= 6.400 Km

R= 700.400 Km

150.000.000 Km

The sun and the earth

SUN EARTH


by Moisès Morató

R= 6.400 Km

R= 700.400 Km

EARTH


by Moisès Morató

R= 700.400 Km

EARTH


by Moisès Morató

R= 6.400 Km

R= 700.400 Km


by Moisès Morató

0,53º (2D) 0,00027 Sr (3D)

22.995 “suns” / hemisphere

The sky can be filled by near 23.000 suns.


by Moisès Morató

Solar radiation.


by Moisès Morató

R= 6.400 Km

R= 700.400 Km

The power of sun:

1.400 W/m2 of power at 150 milions of Km

570.000.000 ton de H2 a 560.000.000 ton de He per second =

400.000.000.000.000.000.000 de MW


by Moisès Morató

Absolut radiation of the estratosferic radiation in the earth:

1. 4 0 0 W / m2 o f p o w e r


by Moisès Morató

The movement of earth around the sun.


by Moisès Morató

Inclination of axis of rotation

N

S

1 rev. at day

Source: M. Morató.

E W


by Moisès Morató

Inclination of axis of rotation

N

S 23,45º E c l i p t i c p l a n e

1 rev. at day

Source: M. Morató.

I n c l i n a t i o n o f a x i s :

Constant = 23,45º

E

W


by Moisès Morató

1 revolution every 365’25 days

1 revolution every day

The seasons

day/night

Image: M. Morató.

E c l i p t i c p l a n e


by Moisès Morató

Declination

N

S

+ 23,45º

E c l i p t i c

p l a n e

Source: M. Morató.

N

S - 23,45º

S u m m e r W i n t e r


by Moisès Morató

Declination

Source: M. Morató.

+ 23,45 º

- 23,45 º

0 º 0 º

+ 23,45 º


by Moisès Morató

The seasons

Source: M. Morató.

summer (north hemispheri) winter (north hemispheri)


by Moisès Morató

The seasons

Position in summer (north hemispheri) at 12:00 at noon

Source: M. Morató.


by Moisès Morató

The seasons

Position in summer (north hemispheri) 12:00 midnight

Source: M. Morató.


by Moisès Morató

The seasons

Position in winter (north hemispheri) in the 12:00 at noon

Source: M. Morató.


by Moisès Morató

The seasons

Position in winter (north hemispheri) at 12:00 midnight

Source: M. Morató.


by Moisès Morató

Which is the movement of the Sun from the Earth ?

Source: M. Morató.


by Moisès Morató

Source: M. Morató.

The Cercasol tool (findsun)

The movement of the Sun from the earth


by Moisès Morató

Source: M. Morató.

ex: How to follow the sun in BCN ?


by Moisès Morató

Source: M. Morató.

1.- Put the axis in direction North


by Moisès Morató

Source: M. Morató.

2.- Inclinate the axis = latitude of place = 41º


by Moisès Morató

Source: M. Morató.

3.- Incline the arrow = declination of the day

N= day of year (N =1 of January)


by Moisès Morató

Soltice of summer (21 June)

Source: M. Morató.

Equinox spring and autumn (21 March/ 22 September)

Soltice of winter (21 december)

declination (+ 23,45º) declination (0º) declination (- 23,45º)

The 3 special positions of the year


by Moisès Morató

Source: M. Morató.

4.- Rotate (left rotation): 1 revolution at day.


by Moisès Morató

Source: M. Morató.

South

Polar

latitude

1 turn at day

summer

winter

spring-autumn


by Moisès Morató

Source: M. Morató.

declination (- 23,45º)

South

West

Est

North

12:00 solar (Noon) Ex: Track on solstice of

winter (41 º lat North)


by Moisès Morató

Source: M. Morató.

declination (0º)

12:00 solar (Noon) Ex: Track on equinocces (41º

Lat North)

South West

Est North


by Moisès Morató

Source: M. Morató.

12:00 solar (Noon)

Ex: Track on solstice of summer (41 º lat North)

South West

Est

North


by Moisès Morató

Source: M. Morató.

Ex: Position of the “Cercasol” at 23 of December in others places on the earth

N

S

N

S

N

S

N

S S


by Moisès Morató

The nature of the radiation on earth

Source: M. Morató.


by Moisès Morató

Radiation Power

Source: M. Morató.

Radiation Energy

W / m2 kWh / m2 units

mean Instantaneous energy

captured energy in a interval of time

Power (W/m2)

Time (s) t1 t2

X (W/m2) Z (kWh/m2)

t2

Meaning of power and energy radiation

Power at time t2 is Energy captured between time t1

and t2 is


by Moisès Morató Architecture and solar energy

1. 4 0 0 W / m2 o f p o w e r

Image: Google earth.

Sun, earth and radiation

The nature of the radiation on earth


by Moisès Morató

λ (µm)

visible IR UV

S h o r t w a v e

Distribution of the solar radiation spectrum:

0,5 1,0 1,5 2,0 2,5 3,0

Intensity

0,4 0,7

1. 4 0 0 W / m2 o f s o l a r p o w e r


by Moisès Morató

Stratospheric radiation and Radiation at level of the sea in a clear day

1. 4 0 0 W / m2 o f p o w e r

Image: Google earth.

9 0 0 W / m2 o f p o w e r

1.400 W/m2

900 W/m2

4% 48% 48%

2% 40% 58%


by Moisès Morató

Source: www.oksolar.com.


by Moisès Morató

Source: www.oksolar.com.

Average daily radiation on the earth: 170 W/m2/day = 4 kWh/m2/day

7,2 kWh/m2

4,8 kWh/m2

2,5 kWh/m2

4,4 kWh/m2

3,9 kWh/m2

< 2 kWh/m2


by Moisès Morató

Source: NASA.

0

4

8

0

4

8

0

4

8

0

4

8

0

4

8

0

4

8

0

4

8

J F M A M J J A S O N D

Theoretical distribution of monthly radiation by latitude (kWh/m2/day)

+ 90º

+ 60º

+ 30º

+ 0º

- 30º

- 60º

- 90º

+ 90º

+ 60º

+ 30º

+ 0º

- 30º

- 60º

- 90º


by Moisès Morató

Source: NASA.

Direct and diffuse radiation


by Moisès Morató

Source: Traimar


Source of diffuse radiation

Source of reflected radiation

Source of direct radiation (sun)


by Moisès Morató

Source: Traimar

Global radiation

Direct rad.

Diffuse rad.

Reflected rad.

+

+

=


by Moisès Morató

Source: Traimar

Global radiation

Direct rad.

Diffuse rad. +

Reflected rad.

+

Usually reflected radiation is lower than direct and diffuse radiation then …

=


by Moisès Morató

Source: Google.

In the atmosphere appears the diffuse radiation

Diffuse radiation


by Moisès Morató

Source: Google

Diffuse radiation appears by interaction of direct radiation against atmosphere molecules



by Moisès Morató

Direct and diffuse radiation in a homogeneous clouded sky

100 %

Source: Moisès Morato. www.cercasol.com


by Moisès Morató

Direct and diffuse radiation (W/m2) in homogeneous clouded skies

100 % 80 % 60 %

40 % 20 %

A B C

D E

Source: Moisès Morato. www.cercasol.com


by Moisès Morató

0

1

2

3

4

5

6

7

8

9

A (100 %) B (80 %) C (60 %) D (40 %) E (20 %)

Irrad

iatio

n (k

Wh/

m2/d

ay)

Source: M. Morató. www.cercasol.com.

Evolution of direct and diffuse radiation (kWh/m2/day) in homogeneous clouded skies


by Moisès Morató

Source: UAB (Universitat de Física)

Real graphs of direct and difusse radiation

A fully clear day (june 2006 BCN)


by Moisès Morató

Real graphs of direct and difusse radiation

clear day cloudy day Source: UAB (Universitat de Física)


by Moisès Morató

Source: M. Morató.

Intensity of diffuse radiation in sky can be higher o lower than the sky without clouds.

Diffuse radiation

cap02-Sun and radiation

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