Cindi Hyman

Due to the search for alternative energy carriers, fuel cell technology has peaked the interest of researchers worldwide. Not only do fuel cells offer environmentally friendly emissions, but they are efficient. A fuel cell is an electrochemical device that converts hydrogen and oxygen into heat, water, and electricity. Hydrogen is a fuel that is used to power fuel cells. Unfortunately, hydrogen is an extremely combustible gas that is dangerous to store and distribute. However, the hydrogen storage problem can be eliminated by using liquid methanol as the fuel and implementing a methanol reformer into the fuel cell system. Methanol is a good candidate for the fuel because of its high hydrogen content. Because methanol is hydrogen rich, a methanol reformer produces hydrogen from the methanol. The objective of this project is to develop and simulate a dynamic model of a methanol reformer.

The first step in modeling a methanol reformer is to find kinetic data in literature. The kinetic information for this model is taken from Mizsey et. al. (2001). The four reactions for the reforming process are as follows:

1) Dimethyl Ether Formation:		2CH₃OH <=> CH₃OCH₃ + H₂O
2) Methanol Decomposition:		CH₃OH <=> CO + 2H₂
3) Water Gas Shift:		CO + H₂O <=> CO₂ + H₂
4) Steam Reforming:		CH₃OH + H₂O <=> CO₂ + 3H₂

The equilibrium coefficients (K_eq), the reaction rate expressions, the equilibrium term, the activation energy, and the pre-exponential factor for each reaction were all part of the kinetic data that were found in Mizsey et. al., 2001. The reformer is modeled as a CSTR so it can be safe to assume that conditions (i.e., concentrations) throughout the reactor volume are uniform allowing more simple material balances.

The results from the model are plotted below. The graph shows how the hydrogen flow changes with varying temperature and steam flow rates.

Future work is to performed on the reformer. The model could be optimized based on hydrogen production and start-up times. It is also desired to model the reformer as a plug flow reactor. A plug flow reactor is like adding many CSTRs in series. The PFR reformer model would then be compared and contrasted to the CSTR reformer model to see which is the better model.

P. Mizsey, E. Newson, T. Truong, P Hottinger, Appl. Catal. A 213 (2001) 233-237.

Dynamic Modeling and Simulation of a Methanol Reformer