Control-oriented model of fuel processor for hydrogen generation in fuel cell applications

Abstract

A control-oriented dynamic model of a catalytic partial oxidation-based fuel processor is developed using physicsbased principles. The Fuel Processor System (FPS) converts a hydrocarbon fuel to a hydrogen (H 2 ) rich mixture that is directly feed to the Proton Exchange Membrane Fuel Cell Stack (PEM-FCS). Cost and performance requirements of the total powerplant typically lead to highly integrated designs and stringent control objectives. Physics based component models are extremely useful in understanding the system level interactions, implications on system performance and in model-based controller design. The model can be used in a multivariable analysis to determine characteristics of the system that might limit performance of a controller or a control design.In this paper, control theoretic tools such as the relative gain array (RGA) and the observability gramian are employed to guide the control design for a FPS combined with a PEM-FC. For example this simple multivariable analysis suggests that a decrease in HDS volume is critical for the hydrogen starvation control. Moreover, RGA analysis shows different level of coupling between the system dynamics at different power levels. Finally, the observability analysis can help in assessing the relative cost-benefit ratio in adding extra sensors in the system.

Dynamic Analysis of Load Operations of Two-Stage SOFC Stacks Power Generation System

“…Their definitions are as follows [25]: In order to increase the amount of hydrogen formed it is desirable to provide a higher POX reaction rate than the TOX reaction rate, which can be achieved for values of S close to one. Since there were two moles of hydrogen produced per one mole of carbon monoxide produced in the POX reaction, more oxygen reacted with hydrogen than with carbon monoxide and therefore the ratio λ O2C was kept constant and equal to 0.66 [26].…”

“…For this purpose, a mathematical model for the CPO x reformer applied in this study is based on a well-tested approach developed by Pukrushpan et al [25], where four main chemical reactions are considered. Zhu et al [26] discussed in details the first two reactions of partial oxidation (POX) and total oxidation (TOX) taking place in the CPO x reformer and shown in Equations (1) and (2), respectively:…”

Hydrogen Energy paper 10

“…Among all of the fuel reforming processes, catalytic partial oxidation (CPO) is the most suitable one for mobile applications with rapid start-up, and good tracking ability of load variation. Pukrushpan and Stefanopoulou [5][6][7] applied linearization technique to obtain CPO-Based system transfer function firstly as in Fig.1 (a), and then applied LQ method for the fuel regulation system design. Later Tsai and Lin [8][9] used Quadratic Gaussian methods, this method can achieve better performance than those obtained by the traditional LQ Method.…”

Nonlinear Generalized Predictive Control for Air Flow RateRegulation in the PEM Fuel Cell System

“…In several studies controlling the oxygen excess ratio, defined as the rate between oxygen supply and consumption, is proposed to prevent insufficient oxygen supply. The proposed control strategies include feed forward control strategy [4], feedback linearization control [5], adaptive control [6], fuzzy-PID switching control method [7], and model predictive The proposed strategy is an improved generalized predictive control with stair-like control increment that is used to regulate the oxygen excess ratio at a desired level under load current changed. The proposed controller is based on a CARIMA model which relates the oxygen excess ratio and compressor voltage.…”