Abstract:

Under the appropriate circumstances, hydrogen has the potential to be a widely-used clean fuel with at least a portion of the storage and distribution being accomplished in liquid form. Unfortunately, the lack of modeling tools in the open literature for the evaluation of ideas in this area may delay enabling improvements in the technology. By presenting the background and methods for the modeling of a commercial-scale hydrogen liquefier using publicly available information, it is anticipated that these limitations will be diminished.

In this document, fundamental thermodynamic relationships, heat transfer and pressure drop correlations for catalyst packed and open plate-fin heat exchangers as well as reaction rate estimates for a ferric oxide catalyst using open literature are combined to generate a variety of spreadsheet-compatible computer functions for the modeling of a hydrogen liquefier. Results show that useful process temperature and composition profiles are readily obtained from the simulations and that the correlations for the kinetic conversion of ortho and para hydrogen provide good agreement with the data.

New contributions to the field include the development of hydrogen liquefier simulation routines for catalyst-packed plate-fin heat exchanger sections; thermodynamic property calculations based on an equation of state for hydrogen published by Leachman in 2007; correlations for the coefficients of a logarithmic reaction rate expression for ortho to para hydrogen; all suitable for direct inclusion in a spreadsheet program. In addition, a hydrogen liquefier modification is described that facilitates the delivery to storage of greater than equilibrium composition of para hydrogen to reduce in-situ storage tank conversion losses.