Solar photocatalytic reactors concentrating

Different types of solar photocatalytic reactors have been developed over time. Two main distinctions have been made (i) concentrating versus nonconcentrating reactors and (ii) slurry versus fixed catalyst reactors. These two classifications are not mutually exclusive, and other categories may also be established, for instance, a very important is the one of tubular solar photoreactors. 

Figure 8 Reaction rate optical factor as a function of catalyst concentration for a parabolic trough solar photocatalytic reactor. Adapted from Arancibia-Bulnes and Cuevas 2004, with permission from Elsevier.

Solar photocatalytic reactors can be divided into concentrating and non-concentrating (one sun) systems depending on received irradiatimi [180]. -Non-concentrating solar reactors use intensities equal or lesser than natural solar irradiation, while concentrating solar reactors require intensities that surpass irradiations equivalent to one sun [116]. 

In this section, the behavior of an E. coli suspension during the subsequent dark period is discussed in order to estimate the potential of using the solar (photocatalytic) treatment process in real water disinfection situations. Photocatalytic disinfection at field scale is illustrated using water from the Leman Lake (LLW). Other aspects when using a pilot reactor such as dose, circulation rate and catalyst concentrations are discussed. 

Concentrating collectors are only able to use a limited fraction of fhe diffuse solar radiation. This utilizable fraction can be estimated as the inverse of the concentration ratio of fhe collecfor (1/Cr) (Rabl, 1985). Because of this, parabolic trough photocatalytic reactors, which have a concentration ratio around 15 or higher, miss practically all diffuse radiation. This amounts to losing around half of fhe available UV solar irradiance. 

Wyness, R, Klausner, J. E, and Goswatrri, D. Y, 1994a, Performance of non-concentrating solar photocatalytic oxidation reactors. Shallow pond configuration, J. Solar Energy Eng., 116 8-13. 

Compound parabolic collectors (CPCs) belong to the most promising photocatalytic solar reactors which combine the advantages of parabolic trough concentrator and non-concentrating system [178]. CPCs are low-concentration static collectors with reflective surface and can be designed for any given reactor shape (see Fig. 7.3a) [182]. The CPC reflectors are usually made from polished aluminum... 

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