Thermodynamic analysis of hydrogen production by steam reforming

Department

Mechanical Engineering

Document Type

Article

Publication Title

International Journal of Hydrogen Energy

ISSN

0360-3199

Volume

28

Issue

2

DOI

10.1016/S0360-3199(02)00053-8

First Page

159

Last Page

167

Publication Date

1-1-2003

Abstract

This paper presents thermodynamic analysis of hydrogen production by steam reforming. The analysis treats the chemistry at two levels: a global species balance assuming complete reaction and solution of the equilibrium composition at the specified reformer temperature. The global reaction allows for an energy balance that leads to analytical expressions for the thermal efficiency. We use this to determine the maximum efficiency, and to distinguish between various definitions of efficiency. To obtain a more realistic estimate of the efficiency, the chemical equilibrium solution is combined with a system energy balance, which compares the energy required to vaporize and heat the fuel-steam mixture to the reformer temperature with the heat available from combusting the residual fuels in the reformate stream. The equilibrium solutions are compared to experimental measurements of the species and thermal efficiency of reforming diesel fuel, obtained with prototype compact steam reformers. The observed efficiency is significantly lower than the equilibrium prediction, indicating that both incomplete reaction and heat transfer losses reduce the performance. Published by Elsevier Science Ltd. All rights reserved.

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