New developments using holographic concentration in solar photochemical reactors

Holographic solar energy systems: The role of optical elements

“…In the same work, Stojanoff [21] also proposed holographic mirrors on curved substrate to concentrate diffracted light in chemical reactors. This investigation is specifically developed in [31].…”

Solar Photooxygenations for the Manufacturing of Fine Chemicals—Technologies and Applications

“…The individual mirror elements of 1 m 2 each were made of silver-coated glass, which does not reflect any UV-light. Depending on the desired application, alternative aluminum or holographic reflectors with different reflective profiles could be fitted instead [ 92 , 93 ]. The reactor had a sunlight concentration factor of 30–32 suns and tracked the sun three-dimensionally with an advanced two-axis system during operation.…”

“…To reduce heat-up and hence cooling-water needs, holographic mirrors were furthermore considered for solar photooxygenations [ 92 , 93 ]. These advanced reflectors were adapted to the sensitizer rose bengal with a reflectivity range of 480–620 nm.…”

“…Due to difficulties with the stability of the holographic film, no experimental results have been reported publicly. Preliminary warm-up tests were, however, successfully completed in a smaller custom-built laboratory reactor with an aperture of 0.188 m 2 (20 × 94 cm) and fitted with either aluminum or holographic elements ( Figure 5 b) [ 92 ]. During the experiments, a solution of rose bengal (0.4 g/L) in isopropanol was passed through the loop at a flow rate of 60 mL/min and the temperature differences between in- and outlet of the receiver tube were recorded.…”

Green photochemistry: Production of fine chemicals with sunlight

“…6b), which are designed to reduce warm-up effects (and thus the costs for process cooling) caused by infrared radiation. The given holographic concentrators (2 elements; 20 × 100 cm total) are made of dichromated gelatin (Holotec GmbH/Germany) and show a reflectivity range of 550 ± 140 nm-optimal for the usage of rose bengal [21]. Two experiments were conducted using rose bengal as sensitizer and isopropanol as solvent [18b].…”