Comprehensive investigation of membrane sorption and CFD modeling of a tube membrane humidifier with experimental validation

Schmitz, M.; Welker, F.; Tinz, Sören; Bähr, Matthias; Gößling, Sönke; Kaimer, S.; Pischinger, Stefan

doi:10.1016/j.ijhydene.2022.11.081

Cited by 6 publications

(7 citation statements)

References 43 publications

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“…This can be explained by the fact that three moisture measurements, which are subject to significant uncertainty, are included in the calculation of the mass transfer efficiency, cf. Equation (20). The highest deviations that can be observed in Figure 5 occur at operating points with relatively low vapour transfer rates.…”

Section: Calibration and Validation Of The Cfd Modelmentioning

confidence: 91%

“…CFD models of flat membrane humidifiers are set up and investigated in different studies and are shown to be an accurate tool to investigate the water transfer in membrane humidifiers [15,16,18,19]. Schmitz et al present a 3D CFD model of a hollow fibre humidifier to analyse the sorption behaviour and the water transport in membrane humidifiers and validate the model with measurement data [20]. Even though only a small part of the flow domain is modelled for the CFD analysis, good agreement with measurement data is achieved [20], which motivates our approach to used a downscaled model.…”

Section: Introductionmentioning

confidence: 99%

“…Schmitz et al present a 3D CFD model of a hollow fibre humidifier to analyse the sorption behaviour and the water transport in membrane humidifiers and validate the model with measurement data [20]. Even though only a small part of the flow domain is modelled for the CFD analysis, good agreement with measurement data is achieved [20], which motivates our approach to used a downscaled model. Another 3D CFD model of a hollow fibre membrane module was set up to analyse a gas separation process [21].…”

Section: Introductionmentioning

confidence: 99%

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Analysis of Surrogate Models for Vapour Transport and Distribution in a Hollow Fibre Membrane Humidifier

et al. 2023

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To achieve high efficiency and low degradation of a polymer electrolyte fuel cell (PEMFC), it is necessary to maintain an appropriate level of humidification in the fuel cell membrane. Thus, membrane humidifiers are typically used in PEMFC systems. Parameter studies are important to evaluate membrane humidifiers under various operating conditions to reduce the amount of physical tests. However, simulative studies are computationally expensive when using detailed models. To reduce the computational cost, surrogate models are set up. In our study, a 3D computational fluid dynamics (CFD) model of a hollow fibre membrane humidifier is presented and validated using measurement data. Based on the results of the validated CFD model, a surrogate model of the humidifier is constructed using proper orthogonal decomposition (POD) in combination with different interpolation methods. To evaluate the surrogate models, their results are compared against reference solutions from the CFD model. Our results show that a Halton design combined with a thin-plate-spline interpolation results in the most accurate surrogate humidifier model. Its normalised mean absolute error for 18 test points when predicting the water mass fraction in the membrane humidifier is 0.58%. Furthermore, it is demonstrated that the solutions of the POD model can be used to initialise CFD calculations and thus accelerate the calculation of steady state CFD solutions.

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Section: Calibration and Validation Of The Cfd Modelmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis of Surrogate Models for Vapour Transport and Distribution in a Hollow Fibre Membrane Humidifier

et al. 2023

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“…In the gas channels, it is assumed for simplicity that the liquid water droplets move with the same velocity as the gas due to the gas flow. Consequently, τ lq = 1 is valid there [74]. The transport by capillary forces is determined by the transport coefficient D lq .…”

Section: S Lqmentioning

confidence: 99%

“…Absorption and desorption of water dissolved in the membrane happens in contact with water vapor and liquid water [74]:…”

Section: Membrane Modelmentioning

confidence: 99%

Analysis of Ice Formation during Start-Up of PEM Fuel Cells at Subzero Temperatures Using Experimental and Simulative Methods

Schmitz,

Bahr,

Gößling

et al. 2023

Energies

Self Cite

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Freeze start is a challenge in the commercialization of PEM fuel cells. In this study, ice formation in cell layers is investigated through experiments and simulations. Segmentation of the fuel cell on the test bench allows to determine the local distributions of current density and high frequency resistance over the active cell area. The location and timing of ice formation are analyzed in the experiments. It is shown that the formation of ice lenses can be detected by local measurements of the high frequency resistances. Then, a multiphysical CFD model is built and validated with the measurements and the commonalities and differences between the model results and the experiments are studied. It is shown that the model determines the freeze start behavior very well in wide operating ranges. Together with the findings from the experimental investigations, the model will finally be used to investigate local ice formation in detail.

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Analysis of the effects of fiber positioning on water transfer in hollow fiber humidifiers using cfd and statistical uniformity metrics

Pollak,

Tegethoff,

Koehler

2024

Heat Mass Transfer

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Hollow fiber membrane humidifiers are used in mobile proton exchange membrane (PEM) fuel cell systems to humidify the supply air of the fuel cell and thereby to achieve a sufficient level of humidification of the PEM. A hollow fiber humidifier contains a large amount of hollow fiber membrane that transfers water from the moisture-laden exhaust gas of the fuel cell to the dry supply air along a concentration gradient. In this study, the effect of fiber placement on the water transfer inside hollow fiber bundles is investigated in detail using a validated CFD model of a membrane humidifier. To analyze the effects of fiber positioning, 80 simulations using humidifiers with different fiber numbers and placements are carried out and analyzed for two operating points. Two statistical metrics, the wrap-around discrepancy and a distance-based metric called MaxiMin, are used to assess the uniformity and space-filling properties of the fiber placements. Correlations of the uniformity of fiber placement and the water transfer inside hollow fiber bundles are then identified. Furthermore, it is demonstrated that both, the wrap-around discrepancy and the MaxiMin, can be used as optimization criterion for the fiber placement inside humidifiers to maximize water transfer rates. The optimization leads to an average improvement of 5 % in water transfer compared to a median random fiber distribution.

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Comprehensive investigation of membrane sorption and CFD modeling of a tube membrane humidifier with experimental validation

Cited by 6 publications

References 43 publications

Analysis of Surrogate Models for Vapour Transport and Distribution in a Hollow Fibre Membrane Humidifier

Analysis of Surrogate Models for Vapour Transport and Distribution in a Hollow Fibre Membrane Humidifier

Analysis of Ice Formation during Start-Up of PEM Fuel Cells at Subzero Temperatures Using Experimental and Simulative Methods

Analysis of the effects of fiber positioning on water transfer in hollow fiber humidifiers using cfd and statistical uniformity metrics

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