A Decomposition Strategy Based on Thermoeconomic Isolation Applied to the Optimal Synthesis/Design and Operation of a Fuel Cell Based Total Energy System

2002 ◽  
Author(s):  
Nikolaos G. Georgopoulos ◽  
Michael R. von Spakovsky ◽  
J. Ricardo Mun˜oz
Keyword(s):  
Fuel Cell ◽  
Total Energy ◽  
Proton Exchange Membrane ◽  
Energy System ◽  
Proton Exchange ◽  
Major Advance ◽  
Energy Integration ◽  
Synthesis Design ◽  
Operational Optimization ◽  
Local Decision

A decomposition methodology based on the concept of “thermoeconomic isolation” applied to the synthesis/design and operational optimization of a stationary cogeneration proton exchange membrane fuel cell (PEMFC) based total energy system (TES) for residential/commercial applications is the focus of this paper. A number of different configurations for the FC based TES were considered. The most promising set based on an energy integration analysis of candidate configurations was developed and detailed thermodynamic, kinetic, geometric, and economic models at both design and off-design were formulated and implemented. An original decomposition strategy called Iterative Local-Global Optimization (ILGO) developed in earlier work by two of the authors was then applied to the synthesis/design and operational optimization of the FC based TES. This decomposition strategy is the first to successfully closely approach the theoretical condition of “thermoeconomic isolation” when applied to highly complex, nonlinear systems. This contrasts with past attempts to approach this condition, all of which were applied to very simple systems under very special and restricted conditions such as those requiring linearity in the models and strictly local decision variables. This is a major advance in decomposition and has now been successfully applied to a number of highly complex, highly non-linear, and dynamic transportation and stationary systems. This paper presents the detailed results from one such application.

Dynamic Modeling and Simulation of an Optimized Proton Exchange Membrane Fuel Cell System

2007 ◽  
Author(s):  
M. T. Outeiro ◽  
R. Chibante ◽  
A. S. Carvalho ◽  
A. T. de Almeida
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Cell Model ◽  
Pem Fuel Cell ◽  
Energy System ◽  
Cell System ◽  
Proton Exchange ◽  
Model Parameters ◽  
Sustainable Energy System

Hydrogen and fuel cells are widely regarded as the key to energy solutions for the 21st century. These technologies will contribute significantly to a reduction in environmental impact, enhanced energy security and development of new energy industries. Fuel cells operating with hydrogen have the potential to contribute to the transition for a future sustainable energy system with low-CO2 emissions. In this paper a dynamic PEM fuel cell model, implemented in Matlab/Simulink, is presented. In order to estimate the PEM fuel cell model parameters, an optimization based approach is used. The optimization is carried out using the Simulated Annealing (SA) algorithm. This optimization process evolves converging to a minimum of the objective function. The flexibility and robustness of SA as a global search method are extremely important advantages of this method. A good agreement between experimental and simulated results is observed. This optimized PEM fuel cell model can significantly help designers of fuel cell systems by providing a tool to perform accurate design and consequently to improve system efficiency.

Performance Evaluation of a Small Size Cogenerative System Based on a PEM Fuel Cell Stack

2005 ◽  
Author(s):  
M. Bagnoli ◽  
A. De Pascale
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
High Efficiency ◽  
Thermal Power ◽  
Energy System ◽  
Electric Utility ◽  
Proton Exchange ◽  
Power Demand ◽  
Fuel Cell Stack ◽  
Exchange Membrane

The use of fuel cell systems for distributed generation represents an interesting option due to the intrinsic high efficiency and the potential to reduce the environmental impact of power supply in comparison with thermoelectric plants. In this paper the study of a cogenerative energy system based on a Proton Exchange Membrane fuel cell stack, that should satisfy a small electric utility, is reported; the capability of this cogenerative system to supply electrical and thermal power demand of a civil user has been investigated. In this research the electric efficiency has been calculated as net electric power on chemical power given to the system and the thermal efficiency as thermal power given to user on chemical power in input. Moreover, an energy saving index has been introduced to assess the cogenerative performance of this energy system. The investigation has been developed by experimenting an existing stack of fuel cell and studying its behaviour with a variable power demand. In particular, all the input and output mass flows have been evaluated to have parameters through which the operation of the whole cogenerative system, made by fuel cell stack and all the auxiliaries like compressor and pumps, could be simulated.

Optimal Synthesis/Design of a Pem Fuel Cell Cogeneration System for Multi-Unit Residential Applications–Application of a Decomposition Strategy

2004 ◽  
Vol 126 (1) ◽  
pp. 30-39 ◽  
Author(s):  
Borja Oyarza´bal ◽  
Michael R. von Spakovsky ◽  
Michael W. Ellis
Keyword(s):  
Fuel Cell ◽  
Design Optimization ◽  
Large Scale ◽  
Unit Cost ◽  
Pem Fuel Cell ◽  
Energy System ◽  
Cell System ◽  
Proton Exchange ◽  
Fuel Cell System ◽  
Synthesis Design

The application of a decomposition methodology to the synthesis/design optimization of a stationary cogeneration proton exchange membrane (PEM) fuel cell system for residential applications is the focus of this paper. Detailed thermodynamic, economic, and geometric models were developed to describe the operation and cost of the fuel processing sub-system and the fuel cell stack sub-system. Details of these models are given in an accompanying paper by the authors. In the present paper, the case is made for the usefulness and need of decomposition in large-scale optimization. The types of decomposition strategies considered are conceptual, time, and physical decomposition. Specific solution approaches to the latter, namely Local-Global Optimization (LGO) are outlined in the paper. Conceptual/time decomposition and physical decomposition using the LGO approach are applied to the fuel cell system. These techniques prove to be useful tools for simplifying the overall synthesis/design optimization problem of the fuel cell system. The results of the decomposed synthesis/design optimization indicate that this system is more economical for a relatively large cluster of residences (i.e. 50). Results also show that a unit cost of power production of less than 10 cents/kWh on an exergy basis requires the manufacture of more than 1500 fuel cell sub-system units per year. Finally, based on the off-design optimization results, the fuel cell system is unable by itself to satisfy the winter heat demands. Thus, the case is made for integrating the fuel cell system with another system, namely, a heat pump, to form what is called a total energy system.

Highly proton conductive membranes based on carboxylated cellulose nanofibres and their performance in proton exchange membrane fuel cells

2019 ◽  
Author(s):  
Valentina Guccini ◽  
Annika Carlson ◽  
Shun Yu ◽  
Göran Lindbergh ◽  
Rakel Wreland Lindström ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Surface Charge ◽  
Proton Exchange Membrane ◽  
Membrane Surface ◽  
Proton Exchange ◽  
Membrane Thickness ◽  
Fuel Cell Performance ◽  
Cellulose Nanofibres ◽  
Exchange Membrane

The performance of thin carboxylated cellulose nanofiber-based (CNF) membranes as proton exchange membranes in fuel cells has been measured in-situ as a function of CNF surface charge density (600 and 1550 µmol g<sup>-1</sup>), counterion (H<sup>+</sup>or Na<sup>+</sup>), membrane thickness and fuel cell relative humidity (RH 55 to 95 %). The structural evolution of the membranes as a function of RH as measured by Small Angle X-ray scattering shows that water channels are formed only above 75 % RH. The amount of absorbed water was shown to depend on the membrane surface charge and counter ions (Na<sup>+</sup>or H<sup>+</sup>). The high affinity of CNF for water and the high aspect ratio of the nanofibers, together with a well-defined and homogenous membrane structure, ensures a proton conductivity exceeding 1 mS cm<sup>-1</sup>at 30 °C between 65 and 95 % RH. This is two orders of magnitude larger than previously reported values for cellulose materials and only one order of magnitude lower than Nafion 212. Moreover, the CNF membranes are characterized by a lower hydrogen crossover than Nafion, despite being ≈ 30 % thinner. Thanks to their environmental compatibility and promising fuel cell performance the CNF membranes should be considered for new generation proton exchange membrane fuel cells.<br>

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