The graphite solar thermal storage system composed of Steps 1–4 (Rotating-Reactive-Ceramics-reactor, RRC-reactor, is used in Steps 1,2,3, and Graphite Thermal Storage tank, GTS-tank, is applied for Steps 3,4,5; Step 3 is the interface-process taking place between the surfaces of RRC-reactor and GTS-tank.) has been studied using computer simulation of COMSOL. During a rapid heating of reactive ceramics in RRC-reactor by irradiation of a high flux concentrated solar beam to around 1800K, the beam energy is directly absorbed by formation of an excess amount of the Frenkel defect in nonequilibrium state of the reactive ceramics without releasing the O2 gas (Step 1; beam energy absorption step). When the temperature reaches around 1800K, the O2 releasing reaction takes place and the reactive ceramics is reduced (Step 2; O2 releasing step). By rotating the RRC-reactor, the surface of reduced reactive ceramics comes to closely face to the surface of the top of GTS-tank. By introducing O2 gas into the space between the two surfaces, the reduced ceramics can be oxidized. The calorification energy produced by the oxidation can be transferred to GTS-tank through its surface. (Step 3; calorification and heat transfer step). The heat is successively transferred and stored in GTS-tank by continuous rotation of RRC-reactor (Sep 4; storage step). The high flux of the concentrated solar beam in the Beam-down concentration system can be averaged in the range of 800–1500kW/m2 in Step 3 by the present process. The computer simulation study showed that it is possible to operate the molten salt heat circulation systems for the GTS-tank at the inlet and outlet temperature of 827K and 1173K, respectively.

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