What are the design considerations for photochemical reactors?

Key considerations: light source selection (UV lamps, LEDs - wavelength matching absorption spectrum), reactor geometry for uniform light distribution, photon efficiency (quantum yield), light attenuation in absorbing medium (Beer-Lambert law), residence time in illuminated zone, heat management (from lamps and reaction), scale-up maintaining uniform illumination (thin films, annular designs), and catalyst photostability for photocatalytic reactions. Challenges: photon delivery efficiency decreases with scale. Emerging: micro-photoreactors, solar concentrators, and flow photochemistry for pharmaceuticals.