3. Parabolic Trough Collector Concepts

Material	density [kg/m^3]
Young's modulus [GPa]
Steel	7850	210
Aluminum	2710	70
Sandwich Composite (et. Schapitz 2011):
i. Fiberglass	1460	25.25
ii. Foam	25	1.7
iii. Thin glass	2500	70
Ultra-High Performance Concrete- (UHPC) e.g. Nanodur®, Ductal®	-2510	0.045 - 0.053

(i) Fiberglass sandwich composite structures

The first subdivision includes the Solarlite SL4600+ and the Tough Trough collector. In general the elements are constituted of a three layered composite. The outer layer is a mat of fiber glass and resin, which encloses an inner core usually of Polystyrene (PS) or injectable Polyurethane (PU) foam, see Figure 32. In both cases the structure results in an increased bending stiffness, where epoxy resin is utilized in the case of a PU core.

In addition to the higher stiffness, the production of sandwich composites has the advantage that the mirror material is incorporated directly in the manufacturing process. For this purpose an

adhesive technology is applied. Furthermore, the reverse side of the composite is equipped with a

UV-stable protection to avoid the material's degradation.



Figure 32 Self-supporting fiber glass reinforced sandwich structure [47]

(ii) High performance fiber reinforced concrete

This subdivision is represented by two examples, namely the SOL.CT and the ConSol collectors. The Airlight collector corresponds also to a further concept with this properties section, but it is sorted in 3.5 Category D: Enclosed Aperture Collectors due to its prevalent characteristic of an enclosed aperture.

Ultra-high performance concrete (UHPC) is commercially used for architecture and civil infrastructures, which require great durability and tensile strength. A composition example of an UHPC is shown in Table 5. For the application on parabolic trough confectioning specific machinery is needed, e.g. mixture machines for concrete processing, transportation cranes and molding elements. Due to the intended apertures and large size elements a production hall is required, which should also be big enough to enable the storage of the pieces while hardening.

Table 5. Example mixture of an UHPC composition [48]

Material