Modelling of start-up time for high temperature polymer electrolyte fuel cells

Start-up time is one of the important factors that limit the application of high temperature polymer electrolyte fuel cells in several areas. Present work involves the analysis of different warm-up methodologies to analyse the start-up time for phosphoric acid doped PBI membrane based fuel cells. With this objective a number of three dimensional thermal models have been developed. Different heating methodologies such as reactant heating, coolant heating and combined heating (reactant and ohmic) are simulated. The ohmic heating is implemented for generating heat in the membrane itself at high current densities. Hence, combining it with other heating techniques is found effective in reducing start-up times significantly. (C) 2011 Elsevier Ltd. All rights reserved

Modeling and experimental validation of a unitized regenerative fuel cell in electrolysis mode of operation

Unitized regenerative fuel cell (URFC) is considered to be the compact solution to generate and utilize hydrogen. It possesses combined capabilities of operating in fuel cell and electrolyser modes. In the present study, the performance of a URFC in electrolyser mode is modelled and also experimentally validated. The performances are being modelled using a combination of structural and CFD analysis tool. The effect of the operating gas pressure on the variation in the contact pressure between GDL and BPP on the performances are studied. The clamping pressure, as well as the operating pressure of the electrolyser, are seen to have a high impact on the contact resistance and thereby the performance as well. It is observed that the simulated polarization behavior is in good agreement with the experimental results. To restrict the area specific resistance below 150 m Omega) cm(2) the operating pressure should be maintained below 5.9 bar at clamping pressure of 1.5 MPa. (C) 2017 Elsevier Ltd. All rights reserved

Study of PEM Fuel Cell End Plate Design by Structural Analysis Based on Contact Pressure

A fuel cell stack is configured to power any load ranging from watts to megawatt by varying cells connected in series. During stack assembly, major emphasis must be placed on application of adequate external pressure for reducing the ohmic losses, the purpose of which is to achieve proper contact between the cell components and minimize the contact resistance. Present work aims to study the influence of geometry of the cell, bolt configuration, gasket thickness mismatch, and material properties of different components of average and distribution contact pressure. The geometries are evaluated for end plate designs with a view to understand the pressure distribution and contact resistance in each case. Among different designs, extruded hexagon is found to perform well with an average contact pressure of 0.13 MPa and contact resistance of 28 Ω-cm2. Greater gasket thickness requires higher forces to be applied before the GDL makes contact with BPP. The effect of gasket thickness mismatch is evaluated for different values to identify its appropriate value. The pressure is applied using bolts and position and number of bolts is determined for homogeneous contact pressure on the active area. This study provides a framework for future end plate design of fuel cells

Study of contact resistance at the electrode-interconnect interfaces in planar type Solid Oxide Fuel Cells

Ohmic resistance at the interface of the electrode and the interconnect in Fuel Cells influences the overall performance of a cell. In the present work, contact resistances between interconnect and electrodes in planar type Solid Oxide Fuel Cells (SOFC) under various compression loads and at different temperatures are measured in laboratory scale experiments. The roughness of the electrode and interconnect surfaces is characterized and a mathematical model to determine the contact resistance at the interfaces with known morphology, is proposed. The experimental results are found to be in good agreement with the values obtained from the model. (C) 2013 Elsevier B.V. All rights reserved

SOFC Power Generation System by Bio-gasification

AbstractPower generation using SOFCs, is one of the technologies that can reduce emissions, allow fuel flexibility and achieve high efficiencies. Combining gasifiers with SOFCs would make it possible to extract energy from biomass with lower environmental impact compared to conventional fuel based systems. The hybrid SOFC-gasifier system is best suited for application in standalone systems. The present study shows the performance of a hybrid SOFC for different types of biomass feed. The gasifier reactions are simulated using AspenPlus and a 1D mathematical fuel cell model is used for calculating the SOFC performance. Amongst different biomass fuels chosen in our study, sugarcane bagasse shows best performance in hybrid SOFC. The electrochemical performance of the biomass fed hybrid SOFC is found to be less compared to a hydrogen fuelled system. The advantage of the hybrid system is that since energy generation is dependent on biomass feed, energy sustainability can be attained with proper policy and management

Study of contact resistance at the electrode-interconnect interfaces in planar type solid oxide fuel cells

Ohmic resistance at the interface of the electrode and the interconnect in Fuel Cells influences the overall performance of a cell. In the present work, contact resistances between interconnect and electrodes in planar type Solid Oxide Fuel Cells (SOFC) under various compression loads and at different temperatures are measured in laboratory scale experiments. The roughness of the electrode and interconnect surfaces is characterized and a mathematical model to determine the contact resistance at the interfaces with known morphology, is proposed. The experimental results are found to be in good agreement with the values obtained from the model. (C) 2013 Elsevier B.V. All rights reserved

A new modified-serpentine flow field for application in high temperature polymer electrolyte fuel cell

Flow field design for the distribution of reactants and products on the electrode surface plays an important role in the overall performance of the fuel cell. It acts as a crucial factor when the laboratory scale fuel cell is scaled up for commercial applications. In the present work, a novel flow field design is proposed and its usefulness for the fuel cell applications are evaluated in a high-temperature polymer electrolyte fuel cell. The proposed geometry retains some of the features of serpentine flow field such as multiple bends, while modifications are made in its in-plane flow path to achieve comparatively uniform reactant and product distribution. A three-dimensional CFD model is developed to analyze the effectiveness of the proposed flow field. An HT-PEFC is fabricated and experimented with the proposed flow field for experimental validation. Furthermore, a low-cost current distribution mapping device is developed to validate the current density distribution on the electrode obtained from the CFD model. It exhibits a mismatch of 4% in the spatial distribution of current density between the modelling and experimental results. The proposed design is capable of achieving higher uniformity in current distribution across the active area (0.998 for modified serpentine and 0.96 serpentine) compared to serpentine flow field. This aids in boosting the current density of the cell by 27% at 0.57 V operations. (C) 2017 Elsevier Ltd. All rights reserved

L'énergie électrique en France en 1948.

Varon Henri. L'énergie électrique en France en 1948.. In: Annales de Géographie, t. 58, n°311, 1949. p. 270

Improvement in solid oxide fuel cell performance through design modifications: An approach based on root cause analysis

Performance of the solid oxide fuel cell (SOFC) is significantly affected by ohmic and concentration losses. The ohmic losses increase with reduction in macroscopic and microscopic contact area at the interfaces of different components. On the other hand, the concentration losses depend on the distribution of fuel and oxidant over the active area. Present work aims to investigate the performance improvement through design modifications obtained from root cause analysis. The influence of the interfacial resistance (ohmic), both, in terms of the external compression load, i.e., the interaction at the microscopic level and macroscopic contact area, is minimised. The effect of the uniformity of the flow distribution on the performance of the scaled up SOFC is analysed. To these objectives, the base configuration is modified and the influence of the different modifications on the electrochemical performance is studied. At 0.7 V, the performance is observed to be enhanced by 62% through minimization of the contact resistance between interconnect and electrode. It is further improved by 100% with an increase in the apparent contact area for a given cell. Additional 50% enhancement in performance is observed by achieving better uniformity in the flow distribution. Overall similar to 212% enhancement in the performance is achieved with a design, which consists of all the modifications in one cell. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved