Session: 06-05 Fuel Cell Driven Cycles II

Paper Number: 126934

126934 - A Holistic Conceptual Synthesis and Analysis of Fuel Cell System Architectures Using 1D Coupled Thermofluid and Electrochemical Lumped Parameter System Simulation 

Fuel cells are an important piece of the power and propulsion system matrix that may enable the decarbonization of power generation, transportation, and other industries, supposing that their fuel – typically hydrogen – is produced in a “green” way. Two critical aspects of fuel cell based power systems that are pertinent to and addressed in this work are (i) the fuel cell proper is typically the singular most expensive component and often drives the system cost and (ii) the system consists of a complex set of fluid handling equipment, at the core of which is often turbomachinery, that are critical to maintaining the proper operation of the fuel cell. Pursuant to the two points above, the system architecture has an enormous impact on the parameters under which the fuel cell operates and therefore addresses the two points by optimizing gravimetric or volumetric system power density or alternatively fuel cell specific power density or even system efficiency, and determination of novel viable system architectures that may integrate the thermal management, oxidant (air) delivery, and exhaust systems.

In this work, we first describe several system architectures and suggest what may be each’s niche application. The architecture variability includes the use of air or liquid cooling, the inclusion or exclusion of an energy recovery turboexpander on the exhaust, and, for those that include a turboexpander, the inclusion or exclusion of thermal recuperation. Additionally, the energy system coupling of the exhaust turboexpander is alternatively arranged to either an independent generator or as directly coupled to the aspirant compressor.

It is recognized a-priori that certain architectures will have specific advantages over others. It is also recognized that there are several performance metrics that may be sought. They include power system efficiency, gravimetric power density, volumetric power density, and specific cost per capacity. The last metric, which is really just a cost power density, is often relegated to a traditional technoeconomic analysis that usually compares electrochemistries. While technoeconomic analysis is not the subject of this paper and we do not explicitly quantify costs, we suggest a novel way to optimize cost on a fundamental engineering system design level. Specifically, knowing that the fuel cell proper represents the highest cost component of a fuel cell based power system, it is shown that one can optimize for maximum “bang for the buck” in a surrogate fashion in a holistic system analysis. The key to being able to achieve this is having a reliable electrochemical analysis model of a cell coupled with an overall system. Thus, for a variation of parameters, it can be predicted what the fuel cell (not system) thermodynamic efficiency and power density is. This is highly valuable because such a holistic systems approach enables the system designer to develop an architecture that perhaps is not maximally optimal from a system efficiency or gravimetric power density standpoint, but achieves sufficiently good values under such metrics while enabling unprecedented power density “per cell stack” (a surrogate for cost indication). It is anticipated that lowering the system cost in this way can enable penetration of hydrogen power systems to markets that are sensitive to cost yet intolerant of the NOx emissions that internal combustion based systems generate.

The outcome of this paper is a documentation of several integrated fuel cell system architectures with a parametric analysis and resulting performance metrics of each system when independently optimized for efficiency, power density, and fuel cell specific power capacity. It is anticipated that the results presented here will lead to future work that includes detailed technoeconomic analysis and that will ultimately result in improved and better optimized fuel cell system designs.

Presenting Author: Vlad Goldenberg SoftInWay

Presenting Author Biography: Vlad Goldenberg leads advanced development of SoftInWay's products as well as special research, development, and engineering consulting service projects. Vlad has been applying fundamental and reduced order physics modeling and simulation methodologies for almost 2 decades in the power, propulsion, refrigeration, and aerospace sectors. His latest (but maybe not last) degree is a Ph.D. in mechanical engineering from the University of Minnesota, and he is also a licensed professional engineer in the state of Minnesota, USA. Vlad believes that "sharing is caring" is a great philosophy for life and invites others who share these passions to connect.

Authors:

Vlad Goldenberg SoftInWay
Ben Conser SoftInWay
Clement Joly SoftInWay
Leonid Moroz SoftInWay