Evaluation of thermal efficiency to produce hydrogen through the IS process by thermodynamics

Nomura, Mikihiro; Kasahara, Seiji; Onuki, Kaoru

JAERI-Research 2002-039, 24 Pages, 2003/01

JAERI-Research-2002-039.pdf:1.01MB

Thermal efficiency to produce hydrogen from water through the IS process was evaluated by a viewpoint of thermodynamics. Thermal efficiency is decided by a temperature from a heat source and limited by the works calculated by the Carnot efficiency for any hydrogen production methods. The maximum thermal efficiency is 81.3% for a thermal cycle between 1123K and 733K. The thermal efficiency of the IS process was evaluated by G-T diagrams of each reactions and separation processes. The maximum value is 78.2% without considering the works for separations of acids from water. However, the effects of the works for separations on thermal efficiency are essential for the IS process, because Gibbs energies of separations of acids from water are always positive. The thermal efficiency could be changed from 53.5% to 76.6% by the calculation with or without the separation processes.