Influence of the anodic recirculation transient behaviour on the SOFC hybrid system performance

Ferrari, Mario L.; Traverso, Alberto; Magistri, Loredana; Massardo, Aristide F.

doi:10.1016/j.jpowsour.2005.01.059

Cited by 99 publications

(45 citation statements)

References 9 publications

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“…(1) The steam-to-carbon ratio in the fuel cell fuel supply must be greater than two to avoid carbon coking in the fuel lines, reformer, and fuel cell stack [6,[10][11][12]. (2) Electrochemically active fuel species (mainly hydrogen) cannot be depleted in the fuel cell [6,10,13].…”

Section: Introductionmentioning

confidence: 99%

Novel solid oxide fuel cell system controller for rapid load following

Mueller

Jabbari

Gaynor

et al. 2007

Journal of Power Sources

134

124

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A novel SOFC system control strategy has been developed for rapid load following. The strategy was motivated from the performance of a baseline control strategy developed from control concepts in the literature. The basis for the fuel cell system control concepts are explained by a simplified order of magnitude time scale analysis. The control concepts are then investigated in a detailed quasi-two-dimensional integrated dynamic system model that resolves the physics of heat transfer, chemical kinetics, mass convection and electrochemistry within the system.The baseline control strategy is based on the standard operating method of constant utilization with no control of the combustor temperature. Simulation indicates that with this control strategy large combustor transients can take place during load transients because the fuel flow to the combustor increases faster than the air flow. To alleviate this problem, a novel control structure that maintains the combustor temperature within acceptable ranges without any supplementary hardware was introduced. The combustor temperature is controlled by manipulating the current to change the combustor inlet stoichiometry. The load following capability of SOFC systems is inherently limited by anode compartment fuel depletion during the time of fuel delivery delay. This research indicates that future SOFC systems with proper system and control configurations can exhibit excellent load following characteristics.

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Section: Introductionmentioning

confidence: 99%

Novel solid oxide fuel cell system controller for rapid load following

Mueller

Jabbari

Gaynor

et al. 2007

Journal of Power Sources

134

124

View full text Add to dashboard Cite

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“…The ejector is required to provide the reformer with a sufficient amount of steam, which has to be enough to fully reformate the NG hydrocarbons (of which CH 4 is the most abundant) as well as to avoid carbon deposition on the catalyst present in the reformer or in the piping within the generator. The ejector behaviour for SOFC applications is well described in [21,[28][29][30]. The fluid-dynamic equations used in this work are those proposed by Zhu et al [28,29].…”

Section: Ejectormentioning

confidence: 99%

“…This effect is avoided by the control system increasing the air flow into the stack, leading to an augmented cooling of the generator. The air flow in the generator (and consequently the air stoichiometry ... [29] ... [30] ... [31] ... [34] ... [28] . number) is also regulated by the control system to avoid an excessively high temperature increase in the after-burner zone.…”

Section: Figure 20 -Generator Temperatures Behaviour During the Ethanmentioning

confidence: 99%

Residential Solid Oxide Fuel Cell Generator Fuelled by Ethanol: Cell, Stack and System Modelling with a Preliminary Experiment

Lanzini¹,

Santarelli²,

Orsello³

2010

Fuel Cells

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The flexibility and feasibility of a 5 kW SOFC generator designed for natural gas (NG) and fuelled by a non‐conventional liquid fuel such as ethanol is analysed. A complete generator model is implemented to predict and determine the main criticalities when ethanol fuel is adoperated. The main balance‐of‐plant (BoP) units considered are the reformer, the recirculation system based on an ejector, the tubular cells bundles constituting the stack unit, the after‐burner zone and the air blower. The electrical and global efficiencies achieved at nominal operating conditions show how ethanol maintains generator performance good, while only slightly reducing the system AC efficiency from 48% (achieved by NG) to 45%. The effectiveness and flexibility of the recirculation system when changing the fuel is also verified since a safe steam‐to‐carbon ratio (STCR) is established after the fuel is switched from NG ethanol. The stack thermal management is analysed in detail and related to the system performances, showing how a high endothermic fuel reforming reaction is required to maintain the overall system efficiency. A preliminary experiment with ethanol feeding the Siemens generator is finally presented. The system response to the new fuel is monitored by several measured parameters and the system regulation is explained.

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“…Compressor (GT and hybrid) Avoid surge and choke Maintain on map Turbine (GT and hybrid) Maintain shaft speed to avoid turbine damage Shaft speed <97000 rpm Turbine inlet temperature must be maintained to avoid thermal degradation of turbine TIT < 1600 K Metal heat exchanger (GT and hybrid) Maintained heat exchanger maximum temperature to avoid heat exchanger thermal damage [38][39][40] T < 950 K Planar fuel cell (hybrid) Sufficiently high steam to carbon ratio to avoid carbon coking [17,[40][41][42] S/C > 2 Sufficiently high minimum MEA temperature for ionic conductivity T MEA > 1000 K Limited MEA maximum temperature to avoid thermal degradation and MEA damage T MEA < 1373 K Managed temperature gradient across the MEA to manage stresses caused by thermal gradients [17,41,[43][44][45] T cathode < 200 K Operating temperature should be maintained as close as possible to avoid thermal fatigue [17,40,43] T MEA < 20 K Fuel cannot be depleted in the anode to avoid oxidation of anode electrode [17,41,46] U fuel < 95% Air cannot be depleted in the cathode to avoid reduction of the cathode electrode U air < 30%…”

Section: Concept Valuementioning

confidence: 99%