Numerical Modeling of High-Temperature Shell-and-Tube Heat Exchanger and Chemical Decomposer for Hydrogen Production

Document Type

Article

Publication Date

10-2008

Publication Title

International Journal of Hydrogen Energy

Volume

33

Issue

20

First page number:

5460

Last page number:

5468

Abstract

Numerical simulations of shell-and-tube heat exchanger and chemical decomposer with straight tube configuration and porous media were performed using FLUENT6.2.16 to examine the percentage decomposition of sulfur trioxide. The decomposition process can be a part of sulfur–iodine (S–I) thermochemical water splitting cycle, which is one of the most studied cycles for hydrogen production. A steady-state, laminar, two-dimensional axisymmetric shell-and-tube model with counter flow and parallel flow arrangements and simple uniform cubical packing was developed using porous medium approach to investigate the fluid flow, heat transfer and chemical reactions in the decomposer. As per the investigation, the decomposition percentage of sulfur trioxide for counter flow arrangement was found to be 93% and that of parallel flow was 92%. Also, a high pressure drop was observed in counter flow arrangement compared to parallel flow. The effects of inlet velocity, temperature and the porous medium properties on the pressure drop across the porous medium were studied. The influence of geometric parameters mainly the diameter of the tube, diameter of the shell and the length of the porous zone on the percentage decomposition of sulfur trioxide in the tube was investigated as well. A preliminary parametric study of the mentioned configuration is conducted to explore effects of varying parameters on the decomposition of sulfur trioxide. From the performed calculations, it was found that the Reynolds number played a significant role in affecting the sulfur trioxide decomposition. The percentage decomposition decreases with an increase in Reynolds number. Surface-to-volume area ratio and activation energy were also the important parameters that influenced the decomposition percentage.

A high surface-to-volume area ratio enhances the rate of the chemical reaction and high activation energy decreases the decomposition percentage. The decomposition of sulfur trioxide is calculated and compared for both counter and parallel flow arrangements.

Keywords

Chemical decomposer; Decomposition (Chemistry); Heat exchangers; High-temperature heat exchanger; High temperatures; Hydrogen as fuel; Hydrogen production; Porous materials; Porous medium; Shell-and-tube heat exchanger; Sulfur trioxide; Sulfuric acid decomposition

Disciplines

Chemical Engineering | Energy Systems | Heat Transfer, Combustion | Mechanical Engineering | Oil, Gas, and Energy | Sustainability

Language

English

Permissions

Use Find in Your Library, contact the author, or interlibrary loan to garner a copy of the item. Publisher policy does not allow archiving the final published version. If a post-print (author's peer-reviewed manuscript) is allowed and available, or publisher policy changes, the item will be deposited.

UNLV article access

Search your library

Share

COinS