Solar Fuels and Materials

aperture Opening of a solar cavity receiver. Carnot efficiency Maximum efficiency for converting heat from a high-temperature thermal reservoir at TH into work in a cyclic process and rejecting heat to a low-temperature thermal reservoir at TL, given by 1 TL/TH. exergy efficiency (for a solar thermochemical process) The efficiency for converting solar energy into chemical energy, given by the ratio of the maximum work that may be extracted from a solar fuel to the solar energy input for producing such a fuel. solar cavity-receiver A well-insulated enclosure, with a small opening to let in concentrated solar energy, that approaches a black-body absorber in its ability to capture solar energy. solar concentration ratio Nondimensional ratio of the solar flux intensity (e.g., in ‘‘suns’’) achieved after concentration to the incident normal beam insolation. solar thermochemical process Any endothermic process that uses concentrated solar energy as the source of high-temperature process heat.