Interdigitated Flow Channel Research Articles

Performance Evaluation of a Novel Cold Plate with Double-Layer Interdigitated Flow Channels for Battery Thermal Management

Working temperature is a non-negligible factor that determines the operating performance of lithium-ion batteries which are extensively used in vehicles and the energy storage industry. Therefore, it is essential to maintain the battery temperature within an acceptable range while minimizing power consumption and ensuring uniform temperature distribution. To achieve these goals, a novel cold plate design with double-layer interdigitated flow channels is proposed in this study for efficient prismatic battery thermal management. The newly proposed cold plate design outperforms the serpentine-channel based cold plate under the same working conditions, resulting in significant improvements in both battery temperature and pressure drop. Specifically, the maximum temperature and temperature difference were reduced by over 10%, while the power cost was reduced by approximately 50%. By considering different arrangements of inlet and outlet locations, 32 non-repeating designs of the cold plate flow paths were examined. Relatively good inlet and outlet layouts are determined by comparing battery thermal management metrics including the maximum temperature, temperature difference, uniform index, and pressure drop, as well as the overall performance factors that consider both the battery temperature and power cost. In addition, the effects of the inlet flow velocity are examined to determine the optimal design.

Machine-learning assisted analysis on coupled fluid-dynamics and electrochemical processes in interdigitated channel for iron-chromium flow batteries

This study explores the impact of interdigitated flow channel spacing on electrolyte distribution and flow velocity in porous electrodes, thereby affecting pump consumption and system efficiency. Utilizing a 3D electrochemical flow-coupled model, the research investigates the electrochemical performance and energy efficiency across various channel spacings, specific flow rates, and current densities. It elucidates the mechanisms by which interdigitated channel spacing influences battery performance. Through controlled trial-and-error, the optimal spacing for flow channels in Iron-Chromium Redox Flow Batteries (ICRFBs) was determined to be 4 mm. At a current density of 140 mA/cm2, the voltage efficiency reached 86.3 %, and the pump-based voltage efficiency achieved 85.9 %. To quickly and efficiently explore the impact of each individual parameter on battery efficiency and identify the optimal operating conditions, this study further developed a multi-task machine learning (ML) model. Initially trained on simulation data, the model achieved high predictive accuracy (R2 > 0.88) and effectively linked the interdigitated flow field design of ICRFBs with current density, specific flow rate, and channel spacing. The ML model was then validated through further investigation to ensure its accuracy and to achieve optimum performance efficiency as recommended by the model. This integrated approach offers a comprehensive understanding of RFBs performance under varying conditions, driving advancements in RFBs technology.

Performance analysis of vanadium redox flow battery with interdigitated flow channel

As a key technology of energy storage system, vanadium redox flow battery has been used in the past few years. It is very important to explore the thermal behavior and performance of batteries. This study establishes a three-dimensional model of a vanadium redox flow battery with an interdigitated flow channel design. By adjusting the key parameters of the battery, the temperature and voltage changes of the battery are discussed. The electrochemistry, fluid mechanics, and multi physics phenomenon are involved in the model. Operating temperature, electrolyte flow rate, and current density are investigated as the important parameters. The results show that the electrolyte charge, mass transport, and electrochemical activity change at elevated operating temperature, and the battery discharge voltage increases with increasing the operating temperature. During the charging and discharging processes, the internal temperature of the battery also increases with the increase of the operating temperature, and the temperature distribution of the positive and negative electrodes is uniform, showing that the operating temperature has a slightly less effect on the temperature difference between the positive and negative electrodes. When the electrolyte flow rate is increased, since increasing the flow rate helps to increase the Coulombic efficiency, the discharge voltage of the battery also increases. When the current density is increased, the battery discharge state time is shortened, causing the discharge time to end faster.

Analysis of performance stability under conditions of high & low humidity of polymer electrolyte fuel cells with interdigitated gas flow channels formed on a gas diffusion layer: An X-ray imaging and modeling study

Recently, a new concept was developed for the design of polymer electrolyte fuel cells, based on a flat, solid separator and a porous GDL with interdigitated gas-flow channels. This newly designed cell has demonstrated the ability to overcome the principal issues of the conventional design, in which the interdigitated flow channels are formed on the separator; the latter can experience low performance under high and low humidity conditions. In the present study, we have sought to reveal the mechanism of the performance stability improvement. The temperature and gas flow distributions are calculated by numerical simulation, and the water distribution is visualized by X-ray imaging. From these results, the porous ribs in the newly designed cell are found to play several important roles as follows: under conditions of excess water, the porous ribs help to alleviate water accumulation in the GDL by acting as a reservoir for excess water and also by increasing the temperature in the GDL; and, under conditions of water shortage, the porous ribs alleviate the dry-out of the GDL by withdrawing water from the reservoir and also by decreasing the rate of gas flow forced through the GDL.

A 3D modelling study on all vanadium redox flow battery at various operating temperatures

To understand whether the optimization of the operating/electrode structural parameters are temperature dependent, a 3D numerical model is developed and validated to gain insight into the impact of practical operating temperature (273.15 K–323.15 K) on vanadium redox flow battery (VRFB) performance, in which the property parameters are from published experimental data. The operating temperature is found significantly influence the optimal design of VRFBs. Increasing the inlet flow rate and state of charge (SOC), decreasing the electrode porosity and fibre diameter can all improve the battery performance with interdigitated flow channels, and the improvement increases with increasing temperature. In contrast, decreasing the fibre diameter or porosity increases the flow resistance and costs higher pump consumption, which is more pronounced at a lower temperature due to higher electrolyte viscosity. The effect of electrode thickness is also different at various temperatures. The gradient porosity electrode is applied in VRFB with interdigitated flow channels. The electrochemical performance of VRFB with gradient electrode (porosity increases from 0.8 at channel side to 0.93 at membrane side) performs similarly with the VRFB with 0.8 porosity electrode, while the pressure drop is reduced by 40% at all temperature. This model provides a deep understanding of effects of a wide range of working temperature on the optimization of operating/electrode parameters and on the VRFBs’ performance.

Numerical investigation on the performance of PEMFC with rib-like flow channels

An innovative flow channel inspired by the physical structure of the human rib was developed in this paper. The performance of a proton exchange membrane fuel cell (PEMFC) with the proposed rib-like flow channels under different flow patterns and relative humidity of anode (RH_a) was investigated. Compared with the conventional interdigitated flow channel (CIFC) and cross-flow channel (CRFC), the maximum current density of the counter-flow channel (COFC) was 1.06 A/cm2 at 0.4 V, with enhancements of 4.95% and 2.91%, respectively. In addition, the quantity referred to as non-uniformity N was introduced to quantify the concentration distribution of oxygen, the minimum non-uniformity N of 0.17 was obtained for CRFC, and the COFC exhibited a more uniform concentration distribution of temperature as compared with the CIFC and CRFC, indicating that the COFC would prevent the occurrence of local hot spots. The maximum net power density of COFC was 6.0% and 3.0% higher than that of the CIFC and CRFC. Finally, the maximum current density of RH_a = 30% was 1.06 A/cm2, which was 3.9% and 7.1% higher than that of RH_a = 60% and RH_a = 100%. The temperature with RH_a = 100% was more uniform in comparison with RH_a = 30% and RH_a = 60%, and the mass fraction of H2 decreased with the increase of values of RH_a. The proposed rib-like flow channel can further enrich PEMFC flow channel design and afford novel insights into the application of bionics in fuel cells.

Numerical simulation of the polymer electrolyte membrane fuel cells with intermediate blocked interdigitated flow fields

The main purpose of this paper is to study fuel cell performance using an interdigitated flow field with intermediate channel blocks on the cathode side. Application of an intermediate block in the middle of the interdigitated flow channel is a very new idea aimed at increasing the performance of polymer membrane fuel cells, which in practice result in novel arrangements of interdigitated flow channels. A middle block is desirable because the change in flow channel is minimal, the cost of fabricating bipolar plates does not increase, and it leads to an increase in the transfer rate of reactants into the gas diffusion layer due to enhanced over-rib flow pattern and direction. In this work, a three-dimensional, isothermal, and two-phase model is used to simulate the performance of such fuel cells. The polarization curves, the distribution of reactants on the cathode side, the distribution of liquid water, and the induced transverse flow were analyzed for three type of interdigitated flow fields along with parallel flow fields at reference conditions. The results showed that interdigitated flow fields with middle blocks lead to an increase in reactant transfer to the catalyst layer, an increase in reaction rate, and better removal of the resulting liquid water within the fuel cell. In the reference condition, in terms of maximum power density, the type I interdigitated flow field (without intermediate block) increased the net power by 8.2% compared to the parallel flow field, and the type II and III interdigitated flow fields also increased the power by 12.58% and 9.03%, respectively. At high current density, the type II interdigital flow field had the best performance in terms of enhancing the transfer of reactants to the catalyst layer and the expulsion of liquid water from that layer.

Simulation of an interdigitated flow channel assembled in a proton exchange membrane Fuel Cell (PEMFC)

This short communication deals with designing an interdigitated flow channel fitted in a PEMFC. The flow plate created here through CFD simulations consists of interdigitated channels based on leaf veins with an active area of 50 cm2. CFD simulations of fluid flow, mass transport, and current distribution were conducted using the finite element method (FEM). Experimental and CFD simulations were carried out to characterize the operating conditions applied to the cathode of a PEMFC using different O2–H2O mixtures. Flow velocities ranged from 3 to 5 m/s, while the humidity and temperature were between 80 and 100% and 323–343 K, respectively. A typical pressure drop around 400 Pa was observed over the flow velocities studied in the flow channel. The linear flow velocities found in the gas diffusion layer (GDL) domain were between 2 × 10−7 to 0.98 m/s. The experimental polarization curve showed close agreement with CFD simulations for the current density interval of 0–0.5 A/cm2, where no limitations to mass transport affect the fuel cell responses. The current model and flow channels configuration will be on continuous development considering water transport through the membrane and future application on Anion Exchange Membrane Fuel Cells (AEMFC).

The crucial role of parallel and interdigitated flow channels in a trapezoid flow battery

Rational flow field design is of great importance in reducing polarization and improving performance of a flow battery. Trapezoid flow field possess great superiority over rectangular flow battery but suffers from local electrolyte stagnation and congestion. Considering that parallel and interdigitated flow channels are widely employed in conventional rectangular flow battery to improve the electrolyte distribution uniformity, radial oriented quasi-parallel and quasi-interdigitated channels are designed to optimize the performance of trapezoid flow battery. Combining the results from hydrodynamic simulation, visualization and charge-discharge experiments, it appears that the flow channels contribute to uniform electrolyte distribution and flow acceleration by controlling the flow pattern in a trapezoid flow field. As a result, the polarization and capacity loss of trapezoid flow battery are reduced. Besides, the effect of parameters like channel depth, electrode porosity on the flow pattern is discussed, which indicates the urgency and importance of further geometrical optimization.

Modeling of vanadium redox flow battery and electrode optimization with different flow fields

The fibrous electrode is an essential component of the redox flow batteries, as the electrode structure influences the reactant/product local concentration, electrochemical reaction kinetics, and the pressure loss of the battery. A three-dimensional numerical model of vanadium redox flow battery (VRFB) was developed in this work. After model validation, simulations were conducted to understand the effects of electrode structural parameters on the battery performance. The gradient electrode design, specific surface area, porosity, and different flow fields were studied and optimized. The results show that in the large-size VRFB system, ensuring a large porosity can minimize the concentration polarization, which not only improves the battery performance, and also reduce the pressure loss. To further improve the mass transfer, fibers with larger diameter can be used, and the specific surface area of the electrode can be increased by modifying the surface of the fiber. The battery performance can be significantly improved with increasing specific surface area when the specific surface area is lower than 500,000. However, with further increase in specific surface area, the voltage of the battery remains almost constant at about 1.37 V. Its influence on interdigitated flow channel case is mainly in reducing pressure loss, and on serpentine flow channel case is directly reflected in improving battery performance.

Parametric optimization of wall-mounted cuboid rows installed in interdigitated flow channel of HT-PEM fuel cells

High temperature proton exchange membrane (HT-PEM) fuel cells reduce water management problems and tolerates CO better in a polybenzimidazole (PBI) membrane because they work at temperatures higher than 120 °C. This paper examines the effect of setting wall-mounted cuboid rows in the interdigitated flow channel on the performance of HT-PEM fuel cells through experiments and simulations. The results of numerically analyzing the four flow channels show that setting the wall-mounted cuboid rows in top half parts of the channel can improve the cell performance. The best net electric power occurs at the arrangement of Case I increasing net electric power by 7.82% compared to the smooth interdigitated flow channel.The Case I design is then used to conduct the experiment with L27 orthogonal array of the Taguchi method to determine different optimal combined factors. The best combined factor level raises 191.09% electrical power than that for the minimum pressure loss, but it decreases the pressure drop than that for maximum power up to 17.00%. Applying Nyquist plots compares the internal impedance between various optimal parameters combinations of Case I and the smooth interdigitated flow channel to confirm the polarization performance results.

Increased Current Density of a Redox Flow Battery with a Carbon Paper Partially Modified by Porous Carbon Nanofibers

One of the technical issues of vanadium redox flow batteries with a carbon paper electrode and interdigitated flow channel is the relatively low current density due to insufficient active material transport downstream in the electrode and low reaction interface area. In this study, we propose a new composite electrode structure, i.e., a porous carbon nanofiber layer that is partially added on the carbon paper. The current density of the composite electrode was higher than that of the unloaded carbon paper electrode due to the lower internal resistances of the battery. In addition, the discharge capacity and voltage efficiency during the charge-discharge operation were improved by the composite structure.

Direct Water Injection in Catholyte‐Free Zero‐Gap Carbon Dioxide Electrolyzers

AbstractA zero‐gap flow electrolyzer with a tin‐coated gas diffusion electrode as the cathode was used to convert humidified gaseous CO2 to formate. The influence of humidification, flow pattern and the type of membrane on the faradaic efficiency (FE), product concentration, and salt precipitation were investigated. We demonstrated that water management in the gas diffusion electrode was crucial to avoid flooding and (bi)carbonate precipitation, to uphold a high FE and formate concentration. Direct water injection was validated as a novel approach for water management. At 100 mA/cm2, direct water injection in combination with an interdigitated flow channel resulted in a FE of 80 % and a formate concentration of 65.4+/−0.3 g/l without salt precipitation for a prolonged CO2 electrolysis of 1 h. The use of bipolar membranes in the zero‐gap configuration mainly produced hydrogen. These results are important for the design of commercial scale CO2 electrolyzers.

Interdigitated Flow Channel on a Proton Exchange Membrane Fuel Cell Investigated Using the Response Surface Methodology

Interdigitated Flow Channel on a Proton Exchange Membrane Fuel Cell Investigated Using the Response Surface Methodology

Performance enhancement of interdigitated flow channel of PEMFC by scaling up study

ABSTRACTThe performance of Proton Exchange Membrane Fuel Cell (PEMFC) with various ribs-to-channel-width ratios on the interdigitated flow field has been investigated by scaling-up from 25 cm2 to 36 cm2 and from 25 cm2 to 49 cm2 using Computational Fluid Dynamics (CFD) fluent-14.0 software. The peak power density is reduced by 18% and 25.5% when scaling up from 25 cm2 to 36 cm2 and from 25 cm2 to 49 cm2 active area of PEMFC, respectively. The validation has been done on the 25 cm2 active area with interdigitated flow channel of PEMFC. The combined effect of design and operating parameters of various combinations on an interdigitated flow channel for the performance enhancement of 25 cm2 PEMFC has been studied using optimization technique. For the reliability of the numerical results, experimental validation of 36 cm2 PEMFC with interdigitated flow field is carried out for the rib-to-channel-width ratio of 1:2, pressure of 2.5 bar, temperature of 343 K, and stoichiometric ratio of reactants of 3.5.

Multiphysics Field Distribution Characteristics within the One-Cell Solid Oxide Fuel Cell Stack with Typical Interdigitated Flow Channels

Generally, the manufacturing technology of fuel cell units is considered to satisfy the current commercialization requirements. However, achieving a high-performance and durable stack design is still an obstacle in its commercialization. The solid oxide fuel cell (SOFC) stack is considered to have performance characteristics that are distinct from the proton exchange membrane fuel cell (PEMFC) stacks. Within the SOFC stack, vapor is produced on the anode side instead of the cathode side and high flow resistance within the fuel flow path is recommended. In this paper, a 3D multiphysics model for a one-cell SOFC stack with the interdigitated channels for fuel flow path and conventional paralleled line-type rib channels for air flow path is firstly developed to predict the multiphysics distribution details. The model consists of all the stack components and couples well the momentum, species, and energy conservation and the quasi-electrochemical equations. Through the developed model, we can get the working details within those SOFC stacks with the above interdigitated flow channel features, such as the fuel and air flow feeding qualities over the electrode surface, hydrogen and oxygen concentration distributions within the porous electrodes, temperature gradient distribution characteristics, and so on. The simulated result shows that the multiphysics field distribution characteristics within the SOFC and PEMFC stacks with interdigitated flow channels feature could be very different. The SOFC stack using the paralleled line-type rib channels for air flow path and adopting the interdigitated flow channels for the fuel flow path can be expected to have good collaborative performances in the multiphysics field. This design would have good potential application after being experimentally confirmed.

Numerical analysis for two pass interdigitated flow channel of PEMFC

ABSTRACT The performance of the polymer electrolyte membrane fuel cell (PEMFC) depends on the design and operating parameters. In this study, the performance of the interdigitated two pass flow channel for a 49 centimetre square active area with various landing to channel width ratios of (L:C) 1:1, 1:2 2:1 and 2:2 of the PEMFC at 1bar pressure , various operating temperature ranges (313,323,333 and 343 K) and a constant mass flow rate of oxygen and hydrogen reactants was analysed numerically. The model was developed and simulated using the CATIA V5 tool and the Fluent CFD 16.0 software, respectively. The L:C-1:2 has produced a maximum power density of 0.292 W/cm2 with constant pressure and an operating temperature of 323 K on the two pass interdigitated flow channel of PEMFC.

Investigation of PEMFC performance with various configurations of serpentine and interdigitated flow channel

The proton exchange membrane fuel cell (PEMFC) performance is influenced by design and operating parameters such as rib to channel width ratio, the depth of the channel, the number of passes on the flow channel, operating pressure, temperature, relative humidity and the inlet gases stoichiometric ratio. In this paper, the PEMFC performance in an effective area of 25 cm2 with various ribs to channel width ratios (R: C - 1:1, 1:2, 2:1 and 2:2) on serpentine and interdigitated flow channels were investigated numerically and experimentally. The numerical and experimental maximum power density deviation of serpentine and interdigitated flow channel results with R:C - 1:2 were found to be 12.16% and 12.2% respectively.

Investigation of PEMFC performance with various configurations of serpentine and interdigitated flow channel

Investigation of PEMFC performance with various configurations of serpentine and interdigitated flow channel

Vanadium redox flow battery with slotted porous electrodes and automatic rebalancing demonstrated on a 1 kW system level

Capacity loss due to electrolyte crossover through the membrane and pump losses due to pressure drop at the porous electrodes are widely known issues in vanadium redox flow batteries during operation. In commercial systems, these losses account for a significant reduction in the overall efficiency. Previous studies have been focused on the development of new membranes to solve the capacity loss, and design modification to reduce the pressure drop. In this work, we propose unique solutions to solve both problems and are demonstrated in a multi-cell stack for the first time. A 20-cell, 1 kW vanadium redox flow battery stack was assembled using thin bipolar plates and porous electrodes featuring interdigitated flow channels. Such a stack design is novel of its kind and can mitigate various problems associated with flow distribution and pump power in flow batteries. In addition, the electrolyte tanks were shunted together to rebalance the electrolyte automatically. The stack showed a very good and stable performance with an energy efficiency of 80.5% at a current density of 80 mA cm−2. The use of hydraulic shunt resulted in a constant capacity over 250 cycles while the use of flow channels on the porous electrodes resulted in ∼40% reduction in pressure drop, compared to a stack with standard felts. The reduction in pressure drop by employing flow channels reduced the pump power proportionally. Overall, capacity retention and utilization of active materials have been improved substantially. These methods are simple and applicable to any size of vanadium redox flow battery.