Collector

To view the Trough System Costs page, click Dish Collector on the main window's navigation menu. Note that for the trough input pages to be available, the technology option in the Technology and Market window must be Concentrating Solar Power - Dish Stirling System.

The collector consists of parabolic mirrors, a support structure, and two-axis tracking system. The mirrors focus direct normal solar radiation on the aperture of the receiver. The receiver aperture size is typically optimized to maximize the quantity of reflected solar radiation that enters the receiver and minimize convection and radiation losses out of the aperture.

The relevant sections of the thesis Stirling Dish System Performance Prediction Model (Fraser 2008) https://www.nrel.gov/analysis/sam/pdfs/thesis_fraser08.pdf (4.1 MB) are:

•	2.1 Parabolic Concentrator, p 7

•	3.1 Parabolic Collector Model, p 63

•	Appendix A: TRNSYS Parabolic Collector Model, p 150

•	Appendix A: TRNSYS Parasitic Power Model, p 158

Input Variable Reference

The parameters on the Collector page are used to calculate the power output of the collector. The parameters are for a single dish collector, and are assumed to apply to each dish in the solar field.

Mirror Parameters

Variable	Description	Units
Projected Mirror Area	Area of one concentrator's mirror projected on the aperture plane. Used to calculated the solar power intercepted by the receiver, and the shading factor.	m2
Total Mirror Area	Area of mirrored parabolic surface. Used to calculate collector diameter, which is used in the rim angle calculation and in the shading factor calculation.	m2
Mirror Reflectivity	Fraction of total radiation incident upon the parabolic mirror surface that is reflected toward the receiver. Used to calculate the solar power intercepted by the receiver.	-

Performance

Variable	Description	Units
Insolation Cut In	Direct normal radiation value above which the cooling system fan operates. Used to calculated parasitic losses.	W/m2

Table 25. Collector default parameter values.

Variable	SES	WGA	SBP	SAIC
Projected Mirror Area	87.7	41.2	56.7	113.5
Total Mirror Area	91.0	42.9	60	117.2
Insolation Cut In	200	275	250	375
Wind Stow Speed	16	16	16	16
Receiver Aperture Diameter for Reference Intercept Factor	0.184	0.14	0.15	0.38
Reference Intercept Factor	0.995	0.998	0.93	0.90
Reference Focal Length of Mirror	7.45	5.45	4.5	12.0