Numerical modeling of hydrogen production from ammonia decomposition for fuel cell applications

Abstract

The hydrogen production from NH(3) decomposition for fuel cell applications using packed Ni-Pt/Al(2)O(3) particles as the catalyst is theoretically and numerically predicted. The results show that by adopting the chemical reaction model for a packed-bed reactor used in the methanol-steam reforming with ZnO/Al(2)O(3) as the catalyst, the numerical model predicted satisfactory results on the NH(3) decomposition efficiency as compared with the experimental data. For various catalyst bed porosities and particle sizes, the numerical results indicated that porosity and permeability of the catalyst bed produce an insignificant effect on the NH(3) decomposition. Based on this finding, a one-dimensional plug flow model is developed and the predicted species molar fraction variations and NH(3) decomposition efficiency are found in good agreement with the numerical simulations. From the numerical and theoretical results, it is found that the NH(3) volumetric flow rate fed into the reactor is an important factor that determines the reaction temperature and decomposition efficiency in addition to the catalyst. Because of a longer NH(3) residence time inside the reactor, lower reaction temperature can be employed for a high decomposition efficiency when the NH(3) flow rate is low. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.