Optimal start-up of micro power generation processes

Barton, Paul I.; Mitsos, Alexander; Chachuat, Benoît

doi:10.1016/s1570-7946(05)80024-0

Cited by 5 publications

(4 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…16,17 In this study, varying power demands are incorporated into the mathematical programming design approach. 15 Most portable electronic devices do not operate at a constant power demand.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Designing man‐portable power generation systems for varying power demand

Yunt¹,

Chachuat²,

Mitsos³

et al. 2008

AIChE Journal

Self Cite

View full text Add to dashboard Cite

in Wiley InterScience (www.interscience.wiley.com).Portable electronic devices operate at varying power demand levels. This variability of power demand must be considered explicitly in the design of man-portable power generation systems for acceptable performance and portability. In this regard, a mathematical programming based design method is proposed. The method transcribes optimal operation of the system at a given power demand into a mathematical program. The power demand specific programs are incorporated into another upper level mathematical program encoding design requirements to form a final two-stage formulation. The design and operational parameters of the power generation system comprise a solution of the formulation. Unlike designs, based on a nominal power demand, the design guarantees that each power demand and all operational requirements can be satisfied. A detailed study of a microfabricated fuel-cell based system is performed. The proposed method produces smaller designs with significantly better performances than nominal power demand based approaches.

show abstract

Section: Introductionmentioning

confidence: 99%

“…A similar study has been published. 16 The ideal operational and design decision variables for a particular demand are obtained as a solution of (14) with P set to the particular demand. The gravimetric fuel energy density (12) is calculated using the ideal design decision variables.…”

mentioning

confidence: 99%

Designing man‐portable power generation systems for varying power demand

Yunt¹,

Chachuat²,

Mitsos³

et al. 2008

AIChE Journal

Self Cite

View full text Add to dashboard Cite

show abstract

“…[32][33][34] Previous work 35,36 has presented a framework for the comparison of alternative fuels, fuel cells, and reaction pathways, which includes heat integration and layout considerations. We previously proposed a methodology for the optimal sizing and steady-state operation of micropower devices, 37 and we considered its extension to transient operation in other research 38,39 and to design for variable power demand in Yunt et al 40,41 This paper combines these approaches, together with detailed modeling, into a methodology for the overall design of man-portable power generation systems. With current computational capabilities and available algorithms, it is impossible to solve for the optimal design and operation in one step, because the devices that are considered involve complex geometries, multiple scales, time dependence, and parametric uncertainty.…”

Section: Introductionmentioning

confidence: 99%

Methodology for the Design of Man-Portable Power Generation Devices

Mitsos

Chachuat

Barton

2007

Ind. Eng. Chem. Res.

Self Cite

View full text Add to dashboard Cite

An overview of a comprehensive methodology for the design of microfabricated fuel cell systems for portable power generation is presented. The methodology is based on a decomposition into three levels of modeling detail: (i) system-level models for process synthesis, (ii) intermediate-fidelity models for optimization of sizes and operation, and (iii) detailed computational fluid dynamics (CFD) models for geometry improvement. Process synthesis, heat integration, and layout considerations are addressed simultaneously through the use of lumped algebraic models, general enough to be independent of detailed design choices, such as reactor configuration and catalyst choice. At the intermediate-fidelity level, space-distributed models are used, which allow optimization of unit sizes and operation for a given process structure without the need to specify a detailed geometry. Finally, the use of detailed CFD facilitates geometrical improvements as well as the derivation and validation of modeling assumptions that are used in the system-level and intermediate-fidelity models.

show abstract

“…The use of mathematical models along with systematic optimization methods is clearly warranted. A simplified version of the start-up problem has been addressed in [9]. In this paper, the concept of intermediate-fidelity models is extended to encompass transient operation.…”

mentioning

confidence: 99%

Optimal start‐up of microfabricated power generation processes employing fuel cells

Chachuat

Mitsos

Barton

2010

Optim Control Appl Methods

View full text Add to dashboard Cite

Microfabricated fuel cell systems have the potential to outperform batteries for man-portable power generation. Because many electronic devices operate at various loads, with frequent start-ups and shut-downs, transient aspects are highly important and must be considered thoroughly. In this paper, the focus is on the optimal start-up of microfabricated fuel cell systems using numerical open-loop optimal control. For start-up purposes, a small rechargeable battery is used to provide the energy needed to heat up the fuel cell stack and meet the power demand when the fuel cell is unavailable or can only satisfy part of the demand. The objective of the start-up problem is to bring the system to a desired operating point with a minimal total mass of the system (battery and fuels), while meeting the nominal power demand at any time and satisfying the operational restrictions. The model for the fuel cell stack consists of partial differential-algebraic equations with multiple time scales and numerical techniques that exploit a separation of these time scales are used for efficient and reliable integration of the state and sensitivity equations. A case study of a microfabricated power generation system employing a high-temperature solid-oxide fuel cell and using ammonia and butane as fuels is presented.These micro processes have the potential to yield much higher energy densities than state-of-the-art batteries, because the abovementioned fuels have very high energy contents, and fuel cells can in principle achieve very high efficiencies.In previous work, a methodology for the design of microfabricated fuel cell systems for portable power generation has been developed [3]. This methodology is based on a decomposition into three levels of modeling: at the system level, lumped algebraic models are used to address the process synthesis, heat integration and layout considerations simultaneously [4,5]; at the intermediate-fidelity level, spatially distributed models are formulated to optimize unit sizes and operation for a given process structure, without the need to specify a detailed geometry [6, 7]; and at the detailed level [8], CFD models are used to facilitate geometrical improvements as well as to derive and validate modeling assumptions that are used in the system-level and intermediate-fidelity models. So far, mainly steady-state aspects have been studied through this methodology.As most power-consuming devices are operated periodically and have rapidly changing power demands, the dynamics and automated operation of portable power production are very important and must be considered thoroughly. In this paper, the focus is on optimization of the start-up of micro power generation processes. For start-up operation, it is most likely that the devices will be coupled with a relatively small, rechargeable battery, whose role will be to ensure that the power demand is met when the fuel cell is unavailable or can only satisfy part of the demand, as well as to provide the energy needed to heat the fuel cell stack up to a tem...

show abstract

Optimal start-up of micro power generation processes

Cited by 5 publications

References 5 publications

Designing man‐portable power generation systems for varying power demand

Designing man‐portable power generation systems for varying power demand

Methodology for the Design of Man-Portable Power Generation Devices

Optimal start‐up of microfabricated power generation processes employing fuel cells

Contact Info

Product

Resources

About