A low-temperature ethanol reformer based on a cobalt catalyst for the production of hydrogen has been designed. The reformer comprises three stages: ethanol dehydrogenation to acetaldehyde and hydrogen over SnO 2 followed by acetaldehyde steam reforming over Co(Fe)/ZnO catalyst and water gas shift reaction. Kinetic data has been obtained under different experimental conditions and a dynamic model has been developed for a tubular reformer loaded with catalytic monoliths for the production of the hydrogen required to feed a 1 kW PEMFC.

This work presents a controllability analysis of a low temperature ethanol reformer based on a cobalt catalyst for fuel cell application. The study is based on a nonlinear dynamic model of a reformer which operates in three separate stages: ethanol dehydrogenation to acetaldehyde and hydrogen, acetaldehyde steam reforming, and water gas shift reaction. The controllability analysis is focused on the rapid dynamics due to mass balances and is based on a linearization of the complex non-linear model of the reformer. RGA, CN and MRI analysis tools are applied to the linear model suggesting that a good performance can be obtained with decentralized control for frequencies up to 0.1 rad/s.

a b s t r a c tThe aim of this work is to investigate which would be a good preliminary plantwide control structure for the process of Hydrogen production from bioethanol to be used in a proton exchange membrane (PEM) accounting only steady-state information. The objective is to keep the process under optimal operation point, that is doing energy integration to achieve the maximum efficiency. Ethanol, produced from renewable feedstocks, feeds a fuel processor investigated for steam reforming, followed by high-and lowtemperature shift reactors and preferential oxidation, which are coupled to a polymeric fuel cell. Applying steady-state simulation techniques and using thermodynamic models the performance of the complete system with two different control structures have been evaluated for the most typical perturbations. A sensitivity analysis for the key process variables together with the rigorous operability requirements for the fuel cell are taking into account for defining acceptable plantwide control structure. This is the first work showing an alternative control structure applied to this kind of process.

A system for ethanol steam reforming and purification of carbon monoxide (CO)\ud designed to feed a PEM fuel cell has been modelled. From the model, we study the\ud sensitivity and controllability emphasizing the study of the influence of the temperature\ud on the output variables of interest. The results of the study of controllability are used for the identification of the best control structures.Peer ReviewedPostprint (published version

This paper focuses on the design of a controller for a low temperature ethanol steam reformer for the production of hydrogen to feed a Protonic Exchange Membrane (PEM) fuel cell. It describes different control structures for the reformer and treats the control structure selection of this Multiple Input Multiple Output (MIMO) system. For each control structure, decentralised 2x2 controllers are implemented and a Proportional Integral (PI) control action is implemented in each control loop. The PI parameters are tuned and the performance of the different linear controllers is compared though simulation. For the evaluation of the proposed controllers, the response time for different initial conditions and changes in the references is analysed, as well as the behaviour of the controlled system in front of disturbances.