G. Maag

Temperature of a Quartz/Sapphire Window in a Solar Cavity-Receiver

Radiation heat transfer within a high-temperature solar cavity-receiver containing a windowed aperture exposed to concentrated solar radiation is solved using the gray-band approximated radiosity method for semitransparent enclosures. Spectrally selective quartz and sapphire are examined for window materials. Window and cavity temperatures are calculated as a function of the incoming radiative flux and solar energy absorption efficiency. For validation and comparability, a windowless cavity is analyzed. Due to its relatively high reflectance in the visible spectrum, the sapphire window requires higher inlet solar radiative flux than the quartz window to obtain the same reactor temperature and energy absorption efficiency.

Hydrogen Production by Steam-Gasification of Petroleum Coke Using Concentrated Solar Power: Reactor Experimentation With Slurry Feeding

We report on the experimental evaluation of a 5 kW solar chemical reactor for the steam-gasification of petcoke, carried out at PSI’s solar furnace. A petcoke-water slurry was continuously injected into a solar cavity-receiver to create a vortex flow directly exposed to concentrated solar radiation. For a nominal reactor temperature of 1500 K, a residence time of 2.4 s, and a water-petcoke molar ratio of 4.8, the maximum degree of petcoke conversion was 87%. Typical syngas composition produced was 62% H2 , 25% CO, 12% CO2 , and 1% CH4 . The energy conversion efficiency — defined as the portion of solar energy absorbed as chemical energy and sensible heat — attained 17%. The effect of varying the particle size (range 8.5–200 μm) and slurry stoichiometry (range 2.1–6.3) on the degree of chemical conversion and energy conversion efficiency was examined.Copyright