Solar radiation (transparent surface)#

The Solar radiation (transparent surface) block describesthe heat exchange by radiation as it falls on a transparentsurface. The calculation takes into account the angles of surfaceinclination and radiation.

Flux density of solar radiationfalling to the surface taking into account angles of inclination (1) :

(1)#\[ q_{\mathrm{с}\mathrm{о}\mathrm{л}\mathrm{н}}^{\mathrm{'}}=q_{\mathrm{с}\mathrm{о}\mathrm{л}\mathrm{н}}\cdot \mathrm{c}\mathrm{o}\mathrm{s}\theta \]

where:

\(q_{sun}\) - [\(\frac{W}{m^2}\)];

\(\cos\theta\) - cosine of the angle between solar radiation and the normal to the surface.

The heat flux of solar radiation is calculated using the following formula (2) :

(2)#\[ Q_{\mathrm{с}\mathrm{о}\mathrm{л}\mathrm{н}}=q_{\mathrm{с}\mathrm{о}\mathrm{л}\mathrm{н}}^{\mathrm{'}}\cdot F \]

where \(F\) - surface area, [m\(^2\)].

Heat flux according to the Stefan-Boltzmann law (3) :

(3)#\[ Q_{\mathrm{и}\mathrm{з}\mathrm{л}}=\sigma \cdot \epsilon \cdot F \cdot \left(T_{1}^{4}-T_{2}^{4}\right) \]

where:

\(\sigma\) - Stefan-Boltzmann constant;

\(\epsilon\) - degree of surface blackness;

\(F\) - surface area of the radiating body, [m\(^2\)];

\(T_1\) - ambient temperature, [℃];

\(T_2\) - surface temperature, [℃].

Heat flux transferred to the surface (4) :

(4)#\[ Q_{\mathrm{п}\mathrm{о}\mathrm{в}}=A\cdot Q_{\mathrm{с}\mathrm{о}\mathrm{л}\mathrm{н}}+Q_{\mathrm{и}\mathrm{з}\mathrm{л}} \]

where \(A\) - absorption coefficient.

Transmitted heat flux (5) :

(5)#\[ Q_{\mathrm{п}\mathrm{р}\mathrm{о}\mathrm{п}}=T\cdot Q_{\mathrm{с}\mathrm{о}\mathrm{л}\mathrm{н}} \]

where \(T\) - transmission coefficient.

Reflected heat flux (6) :

(6)#\[ Q_{\mathrm{о}\mathrm{т}\mathrm{р}}=\left(1 - \mathrm{A} - \mathrm{T}\right)\cdot Q_{\mathrm{с}\mathrm{о}\mathrm{л}\mathrm{н}} - Q_{\mathrm{и}\mathrm{з}\mathrm{л}} \]

Geometry of surface location

All angles required for the calculation are shown in Fig. 1 :

Fig. 1 Geometry of the surface arrangement#

\(\theta_z\) - angle of inclination between the radiation direction and the vertical, °;

\(\gamma_s\) - angle between the projection of the surface normal on thehorizontal plane and the meridian of the point, °;

\(\gamma\) - angle between the projection of the surface normal on the horizontal plane and the meridian of the point, °;

\(\beta\) - angle of inclination of the surface relative to the horizontal plane, °.

\(*\) - Offsets to the east of south are negative, to the west of south - positive.

\[ \mathrm{c}\mathrm{o}\mathrm{s}\theta =\mathrm{c}\mathrm{o}\mathrm{s}\theta _{z}\cdot \mathrm{c}\mathrm{o}\mathrm{s}\beta +\mathrm{s}\mathrm{i}\mathrm{n}\theta _{z}\cdot \mathrm{s}\mathrm{i}\mathrm{n}\beta \cdot \mathrm{c}\mathrm{o}\mathrm{s}\left(\gamma _{s}-\gamma \right) \]

[1]

1. Properties#

Property	Default value	Description	Units of measurement
Surface area	10	–	m\(^2\)
Absorption factor	0.5	–	–
Transmission factor	0.2	–	–
Emissivity factor	0.5	–	-
Solar radiation flux density	800	–	\(\frac{W}{m^2}\)
Slope, β	60	see Fig. 1	°
Angle between the projection of the surface normal on the horizontal plane and the meridian of the point, \(\gamma\)	0	see Fig. 1	°
Angle of inclination between the radiation direction and the vertical, \(\theta_z\)	20	see Fig. 1	°
Angle between the projection of the radiation direction on the horizontal plane and the meridian of the point, \(\gamma_s\)	0	see Fig. 1	°

2. Inputs and outputs#

Parameters	Input/Output	Description	Units of measurement	Port type
Input	Input	Preceding block temperature	-	Heat exchange
Reflected heat flow	Output	–	W	Heat exchange
Output	Output	–	W	Heat exchange
Transmitted heat flow	Output	–	W	Heat exchange

In order to see the connection capabilities of the block, you need to go to page Description of block ports

Solar radiation (transparent surface)#

1. Properties#

2. Inputs and outputs#

3. Sources#