SOLAR UT-3 THERMOCHEMICAL CYCLE FOR HYDROGEN-PRODUCTION

The UT-3 thermochemical hydrogen producing cycle is a four step proces s developed at the University of Tokyo. In the process, only solid and gas reactants/products are used and the maximum temperature is 1033 K . The process has been developed to be coupled with gas cooled nuclear reactors (HTGR). In this article, a new UT-3 process is conceived to be coupled with a solar heat source. In the new process, all four reac tions are carried out in adiabatic equipment where steam (or steam + n itrogen) can be used as a vector. The operation of the process is done continuously. During sunshine hours, the energy to the process is sup plied directly from the solar receiver. During cloudy periods and nigh ts, it is supplied from a thermal storage system where the necessary h igh temperature heat is stored during sunshine hours. The solar UT-3 p rocess has been evaluated using the ASPEN-PLUS code. It is found that the overall thermal efficiency is 49.5%, the exergetic efficiency is 5 2.9% and the process can be realized using conventional materials. Siz ing of a solar hydrogen plant producing 2000 Nm(3) per hour hydrogen h as been carried out and operation of various equipment has been discus sed. Copyright (C) 1996 Elsevier Science Ltd.