Emmanuel Devaud

An identification method for static and dynamic friction coefficients

This paper deals with the identification of static and dynamic friction coefficients. An approach based on limit cycles properties once a regulated mechanical system is brought to oscillations is proposed. This leads to an explicit formulation in the regulator parameters on one part, and the oscillation amplitude and period on the other part. The method is validated by a simulation example and an experimental benchmark.

Analytical Reduced Model of Autothermal Reforming Process for the Control

Abstract The subjects discussed in this paper are motivated by problems arising in the computation of chemical equilibrium for an autothermal reforming process applied to a fuel cell. The composition of a chemical system at chemical equilibrium has been computationally determined by solving certain systems of simultaneous equations. We wish, in this paper, to present the development of a reduced model available for each fuel (methane, butane, gasoline...) and satisfying the different reforming modes, namely partial oxidation and steam reforming. There are two common ways to express the chemical equilibrium. One is based on equilibrium constants, while the other one is minimization of the free energy. The Equilibrium State at specified temperature and pressure is determined by minimizing the Gibbs free energy and is subject to the constraints imposed by conservation of atoms (mass balance). It is possible to have a reduced model summarized in a second order polynomial equation. This model can predict the chemical equilibrium composition and the temperature at the outlet of the reformer. Some parameters of reformer can be used as a key for the temperature control.