Recent Advances in TOYOTA FCHV-adv Fuel Cell System

Sekizawa, Keita; Kitamura, Nobuyuki; Manabe, Kota; Nonobe, Yasuhiro; Kizaki, Mikio; Kojima, Kensuke

doi:10.1149/1.3484686

Cited by 15 publications

(3 citation statements)

References 10 publications

(12 reference statements)

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“…1,2 However, several improvements regarding degradation, performance, and cold start capability have to be achieved to ensure a reliable and durable operation even under extreme ambient operating conditions. 3 The cold start capability of fuel cells has been widely studied on lab-scale [4][5][6][7] as well as on technical fuel cells. 8,9 It has been reported that water does not deposit as ice inside fuel cells; it is produced in its supercooled aggregate state 4,5,7,10 and the phase transition to ice occurs randomly.…”

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confidence: 99%

Statistical Analysis of Isothermal Cold Starts of PEFCs: Impact of Gas Diffusion Layer Properties

Biesdorf

Forner‐Cuenca

Siegwart

et al. 2016

J. Electrochem. Soc.

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In this paper, we present experimental results about the influence of a hydrophobic coating of gas diffusion layers (GDL) and the existence of a micro porous layer (MPL) on the cold start capability of Polymer Electrolyte Fuel Cells (PEFC). The experiments were performed on five different cell configurations with an active area of 1 cm 2 including GDLs of 0, 5, 20 wt% PTFE with and without MPL. Two different experiments were realized: First, a statistical analysis of more than 700 isothermal cold starts was performed to analyze the stochastic freezing behavior of supercooled water inside the fuel cells. Second, a certain number of cold starts were investigated with high-resolution neutron radiography in order to understand the implications of the water distribution on the freezing mechanism. Especially at low coating loads, it was found that cell-to-cell variations are more dominant than variations of the materials. In contrast, a significantly reduced variability between the individual cells as well as a general reduction of the probability of cell failure was observed at high coating loads. The observed effects can be mainly explained by changed morphology of the investigated materials. Regarding the existence of an MPL, only minor effects were observed which could be assigned to a different local distribution of water in the porous layers.

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confidence: 99%

Statistical Analysis of Isothermal Cold Starts of PEFCs: Impact of Gas Diffusion Layer Properties

Biesdorf

Forner‐Cuenca

Siegwart

et al. 2016

J. Electrochem. Soc.

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“…Within the last decade, polymer electrolyte fuel cells (PEFCs) have proven their potential to replace fossil fuel based power generators for stationary as well as mobile applications. However, operation under ambient environment 1,2 requires various enhancements regarding degradation, efficiency as well as cold start capability at subfreezing temperatures, where product water risks to freeze. Subzero cold start investigations have been widely reported.…”

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confidence: 99%

When Size Matters: Active Area Dependence of PEFC Cold Start Capability

Biesdorf

Stahl

Siegwart

et al. 2015

J. Electrochem. Soc.

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Understanding the freezing mechanism of liquid water within polymer electrolyte fuel cells (PEFC) is crucial for its commercialization for mass market. Although various publications investigated the cold start capability of PEFCs, contradictory behaviors during cold starts at freezing temperatures have been published in literature. Interestingly, differences can be mainly identified between large and small size fuel cells: the latter have a significantly higher cold start capability than large size fuel cells. In order to understand the influence of different active areas, we present measurements of cold starts performed with cells sizes of 1 and 50 cm2 using the same materials, including a large count of experiments (>200) on the 1 cm2 cells to perform statistical analysis. The cold start capability is strongly reduced with an increasing size of the active area, and the operating times changes from stochastic values for small cells to reproducible values for large cells. Both effects can be explained by the higher probability of the aggregate state transition from super-cooled water to ice in large cells. Consequently this paper highlights the implications of downscaling PEFCs to draw conclusions for technical relevant cold-starts.

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“…As the membrane can initially absorb the water produced, thus avoiding ice formation and performance drop (8,9). The dry gas purge methods have been extensively studied in the literature (10)(11)(12)(13), reducing the degradation due to F/T cycles. However, there are still unsolved issues, especially at extreme low temperatures (e.g.…”

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confidence: 99%

Automotive Cold Start of a PEMFC System by Using a Methanol Solution as Antifreeze

et al. 2020

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The startup ability and durability at winter conditions has been a key issue for fuel cell vehicles. To reduce ice formation and to improve the cold start and lifetime of the PEMFC system, the remained water is commonly purged with dry gases at shutdown. This paper proposes an alternative cold storage method based on the use of a methanol solution as antifreeze. In order to study the cold start ability of a PEMFC system by using this method, cold start experiments at -10°C were performed with a 4 kW PEMFC stack. The results show that the stack can be successfully started at -10°C after being stored with the methanol solution and after these cold starts no performance degradation was observed. Furthermore, the use of the antifreeze method at shutdown may reduce its time and improve the energy efficiency of the system.

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Recent Advances in TOYOTA FCHV-adv Fuel Cell System

Cited by 15 publications

References 10 publications

Statistical Analysis of Isothermal Cold Starts of PEFCs: Impact of Gas Diffusion Layer Properties

Statistical Analysis of Isothermal Cold Starts of PEFCs: Impact of Gas Diffusion Layer Properties

When Size Matters: Active Area Dependence of PEFC Cold Start Capability

Automotive Cold Start of a PEMFC System by Using a Methanol Solution as Antifreeze

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