Model description
Validated models are used for the parameter analyses [4]. The validation was carried out in 2007 with measurement data from the four different evacuated tubular solar collectors tested in a test facility at the Technical University of Denmark. In Table 1 the values used and determined in the validation process are shown.
Table 1. Parameters for the four solar collectors.
|
Parameter |
Seido 5-8 |
Seido 1-8 |
Seido 10-20 Curved |
Seido 10-20 Flat |
|
Collector type |
||||
|
Total gross area of the collectors [m2] |
2.07 |
2.07 |
3.53 |
3.53 |
|
Transparent area of the collectors [m2] |
1.38 |
1.38 |
2.25 |
2.25 |
|
Number of tubes [-] |
8 |
8 |
20 |
20 |
|
Glass tube radius [m] |
0.05 |
0.05 |
0.035 |
0.035 |
|
Tube centre distance [m] |
0.120 |
0.120 |
0.09026 |
0.09026 |
|
Collector panel tilt [°] |
67 |
67 |
67 |
67 |
|
Collector azimuth [°] |
0 |
0 |
0 |
0 |
|
Incidence angle modifier for the diffuse radiation [-] |
0.9 |
0.9 |
0.9 |
0.9 |
|
Effective transmittance - absorptance product, [-] |
0.83 |
0.83 |
0.83 |
0.83 |
|
Number of discretizations for the absorber [-] |
41 |
41 |
33 |
15 |
|
Angle dependence of tau-alpha product based on tangent equation [-] |
3.8 |
3.8 |
3.8 |
3.8 |
|
Heat capacity of the fluid in the manifold tube [kJ/kgK] |
3.8 |
3.8 |
3.8 |
3.8 |
|
Heat pipe length [m] |
1.73 |
1.73 |
1.61 |
1.61 |
|
Absorber radius [m] / Absorber width [m] |
0.041 |
0.085 |
0.027 |
0.056 |
|
Angle of strip [°] |
164 |
- |
164 |
- |
|
Thickness of strip [mm] |
0.47 |
0.47 |
0.60 |
0.60 |
|
Thermal conductivity of strip [W/mK] |
238 |
238 |
238 |
238 |
|
Density of strip [kg/m3] |
2700 |
2700 |
2700 |
2700 |
|
Heat capacity of strip [kJ/kgK] |
0.896 |
0.896 |
0.896 |
0.896 |
|
Lowest evaporation temperature [°C] |
15 |
15 |
15 |
15 |
|
Manifold heat exchange capacity rate [W/K] |
10 |
10 |
10 |
10 |
|
Mass of the fluid inside the heat pipe [kg] |
0.0038 |
0.0038 |
0.0038 |
0.0038 |
|
Effective heat capacity of the collector [kJ/K] |
4.04 |
3.41 |
6.31 |
4.94 |
