John C. Telotte

Solution thermodynamics for “reactive” components

Abstract A unifying mathematical analysis is presented for the thermodynamic properties of a system of components which undergo chemical transformations (reaction, association, solvation, ionization) or are modelled as such (“chemical theory”, “solutions of groups”) in terms of the properties of the resultant species. Several examples are given.

Miniaturized Methanol Reformer for Fuel Cell Powered Mobile Applications

In this paper, the design of a miniaturized methanol reformer is considered that can operate in two different modes to produce sufficient hydrogen for generating a net power of 24 W and 72 W. The reformer is modeled as a radial flow packed bed reactor and the Ergun equation is used to model the pressure drop. Simulation studies are conducted to study the effect of steam to methanol ratio, inlet pressure and reactor temperature on the production of hydrogen. It is shown that a volume of 20 ml is required to produce sufficient hydrogen for generating the necessary power if an inlet pressure of 202 kPa and a steam to methanol ratio of 1.5 is used. A temperature of 500 K is required for the lower power application while a temperature of 550 K is required for the higher power application.

Design of a Fuel Cell Power System for Automotive Applications

In this paper, the primary components of a PEM fuel cell for automotive applications, using methane as a fuel, are analyzed. Basic chemical engineering principles are utilized to assess the role of thermodynamics, heat transport, and reaction kinetics. The amount of methane required is calculated as function of hydrogen produced as well as the power produced. The heat duty for thermal control of the system is analyzed.

It's Not as Easy as it Looks: Revisiting Peng—Robinson Equation of State Convergence Issues for Dew Point, Bubble Point and Flash Calculations

The use of equations of state (EOS) is a ‘modern’ method of physical property prediction and here we present a detailed exposition of the use of the Peng–Robinson EOS for mixtures. This EOS can be used to determine whether a stream is in the vapor phase or liquid phase. However, for two-phase systems the approaches presented in standard textbooks for the calculation of the state frequently will not converge. We provide modifications to standard dew point, bubble point and flash algorithms to help improve the convergence of any EOS. Commercial software can show different values for stream energetic properties (entropy values) and here we utilize species formation from its elements as well as species ideal gas capacities and mixture departure functions to explain observed differences.

Modeling of a Fuel Cell Power System for Automotive Applications

In this paper, the primary components of a PEM fuel cell for automotive propulsion using methane as a fuel are analyzed. Basic chemical engineering principles are utilized to assess the role of thermodynamics, heat transport, and reaction kinetics. The amount of methane required is calculated as function of hydrogen produced as well as the power produced. The heat duty for thermal control of the system is analyzed.Copyright

Controller design in a fuel-cell powered automobile

Abstract Abstract In this paper, the control problems that arise during dynamic operation of a fuel-cell powered automobile, are analyzed. In particular, it is shown that there are three distinct control problems that need to be solved when the power demand fluctuates. A logic-based switching controller is proposed that switches to the battery backup when the fuel cell is unable to provide the necessary power to the motor. An adaptive controller is developed based on a linear model that adjusts the hydrogen flow into the fuel cell in response to changing power demand. Finally, a thermal controller is developed based on a nonlinear model that regulates the temperature of the fuel cell. Interaction between these controllers is analyzed via simulations under realistic road conditions.

ADAPTIVE CONTROLLER DESIGN FOR TRAJECTORY TRACKING IN A FUEL-CELL POWERED AUTOMOBILE

Abstract In this paper, a model reference adaptive controller is designed using the Lyapunov method, for tracking a time varying power profile in an automobile powered by a fuel cell. The adaptability of the controller is tested by implementing the controller on different power profiles which simulate actual power requirement of different road conditions.

DESIGN AND CONTROL OF A POWER GENERATION SYSTEM FOR A FUEL-CELL POWERED AUTOMOBILE

Abstract In this paper, we consider design and control issues in a fuel-cell powered automobile that utilizes methane as a source of hydrogen. A power generation system is designed based on a steady state model of a PEM fuel cell that is capable of generating 50 kW of power. The transient behavior of the fuel cell is captured via a transfer function model and an appropriate adaptive controller is tuned to follow a time varying power profile that mimics realistic road conditions. Finally, a logic-based controller is designed and tested that switches to a battery backup that provides power to the electric motor when the fuel cell is unable to meet the necessary power demand.