Flux Measurement of a New Beam-down Solar Concentrating System in Miyazaki for Demonstration of Thermochemical Water Splitting Reactors

Abstract

A two-step thermochemical water splitting cycle using nonstoichiometric cerium oxide is a promising solar thermochemical hydrogen production process. One of the present authors has developed new solar reactors using “internally circulating fluidized beds” with cerium oxide particles for the high-temperature cycle. These solar reactors need to be combined with a beam-down solar concentrating system. Niigata University, University of Miyazaki, and Mitaka Kohki Co. Ltd. recently started an R&D joint project to demonstrate the up-scaled fluidized bed reactors with solar. A new type of 100 kWth beam-down solar concentrating system was built in August, 2012 at the campus of University of Miyazaki. This paper describes the first results of solar flux measurements on the new Miyazaki beam-down system for demonstration of thermochemical water splitting reactors. The fluxes of concentrated solar radiation at the focus point were measured by moving an array of thirteen Gardon gauges. The solar power in an area of 130 × 130cm in the focal spot was larger than 90 kWth during three hours of daytime radiation, exceeding 110 kWth around noon on October 12, 2012. A new CPC specific to this new beam-down system was designed and fabricated to concentrate the solar fluxes into a 44cm diameter circle of the solar reactor aperture. The solar demonstration of the reactors will start at the Miyazaki beam-down system from October 2013.