3. Parabolic Trough Collector Concepts

Figure 28 From left to right: double torque box, torque box, torque tube, space frame [44]

7. 
   Assembly jigs, which are usually installed on-site rather in the open sky or in an assembly hall. With the jigs the accurate mounting of the central body and the arms is achieved up to a structure tolerance of 0.5 mm. An assembly without costly jigs is suggested for space frame structures while for other types like the UltimateTrough an automatic assembly line is proposed.
   

Figure 29 (left) assembly jig of a torque box structure [45], (right) assembly jig of a torque tube structure [46]

8. 
   Hydraulic or geared drive system with a tracking axis bellow the vertex of the parabolic cross-section, with optimized properties by placing the tracking axis on the centre of mass axis.
   
9. 
   Flexible interconnection elements such as ball-joints or flex-hoses. These elements suffer from frequent breakdowns during operation and tent to have low resistance against high pressure.
   

Follower Support


Rotating Ball Joint in Rotation Axis


Swivel

Joint

Flexible

Hose

Figure 30 Flexible interconnection elements [43]

The successful deployment of solar fields using several of these concepts for energy production established the basic standards for modern solar power plants in the global market, making them indispensable for the study. Within the category technological advances aiming the cost reduction are observed, for example the standardization of components, simpler assembly structures, manufacturing methods and logistics. A baseline for a solar field cost is drawn by the EuroTrough collector with a total of 230 €/m² in the example of 50MW Andasol and similar solar power plants. Elements included in the cost estimation are later specified.

Solar field efficiency and economic feasibility calculation models conclude that higher concentration ratios can lead to a significant reduction of element square meter. The scaling effect of the collector's aperture can, for example, reduce the total area of the solar field, thus reducing elements like pipelines, receiver tubes, mirrors, pylons and drives among other elements. The efforts to reach these aims are presented in the description of the concepts of this class. It is important to keep in mind that larger apertures are subject to stricter requirements in accuracy and robustness of their structure. Figure 31 shows a timeline with an overview of the collectors and their respective modules dimensions.

CATEGORY A: Conventional Parabolic Trough Concepts