Water Transport Phenomena Research Articles

Aqueous Two-Phase System Formation in Small Droplets by Shirasu Porous Glass Membrane Emulsification Followed by Water Extraction

By utilizing water transport phenomena between two different water-in-oil (W/O) emulsion droplets through continuous oil phase, we developed a novel method of aqueous two-phase system (ATPS) formation in small droplets prepared by Shirasu porous glass (SPG) membrane emulsification technique. When we mixed W/O emulsion droplets containing poly(ethylene glycol) (PEG) and dextran (DEX) at concentrations below the threshold of the phase separation, with droplets containing other solutes at high concentrations, water extraction from the droplets containing PEG and DEX to those containing the other solutes occurred, owing to the osmotic pressure difference. This effect increased the concentrations of PEG and DEX in the droplets above the phase separation threshold. We demonstrated the feasibility of the preparation method by varying the pore sizes of the SPG membranes, the solutes, and their concentrations. Only when the concentration of the solute was high enough to extract sufficient amounts of water did the homogeneous disperse phase consisting of PEG and DEX in droplets turn into a PEG-rich phase and DEX-rich phase, showing ATPS. This result was irrespective of the solute itself and pore size of the SPG membrane. In particular, we successfully demonstrated monodisperse ATPS droplets with diameters of approximately 10 μm under a certain condition.

Effect of channel-rib width on water transport behavior in gas diffusion layer of polymer electrolyte membrane fuel cells

Designparameters of bipolar plate are greatly influencing the mass transfer in polymer electrolyte membrane fuel cells. Water accumulation in the catalyst layer and gas diffusion layer causes the mass transport limitation, resulting in an inhibition of gaseous reactant transport to the reaction sites. To carve out the mass transport problems, the optimum design of flow channel is essential with profound understanding of water transport phenomena. Here, we investigate the effect of channel-rib width on dynamic behavior of liquid water in a gas diffusion layer using the multiphase lattice Boltzmann method. We simulate the various channel-rib width configurations and compare the simulated results. We present the water saturation profile with temporal variations of water distribution and relative pressure distribution. The results show that the channel-rib width plays an important role on water transport dynamics in a gas diffusion layer as well as water breakthrough and creeping. The influence of channel-rib width becomes significant as it increases.

Fabrication of a Peristome Surface Structure of Nepenthes alata by Elliptical Vibration Cutting

The phenomenon of continuous directional water transport on the peristome surface of Nepenthes alata (N. alata) has been found to be of great significance to the applications of microfluids, anti-adhesion surface texture, lubrication and so on. Various methods are used to fabricate the bionic structure of the peristome surface. However, the size of processing area and the fabrication material are limited in the previous methods, which results in the limitation of the bionic structure applications. In order to solve the remained problems of small-scale and limited materials, the mechanical machining is creatively applied to the fabrication of bionic structure of peristome surface of N. alata in this paper. An elliptical vibration cutting system (EVC) driven by mechanical structure is designed and built to satisfy the size requirements of the bionic structure. The surface topographies corresponding to the tool trajectories of cutting and extrusion are obtained, respectively. The results demonstrate that both the two methods can realize the fabrication of bionic inclined microcavities while few defects can be seen on the extruded surface. According to the measured structure dimensions, it can be found the EVC system keeps a superior machining repeatability. As a consequence, the availability of the newly proposed method for the large-area fabrication of the bionic structure is verified.

Water Flow through Interlayer Channels of Two-Dimensional Materials with Various Hydrophilicities

Water transport through laminated membranes composed of two-dimensional (2D) materials has gained considerable attention because of their great potential in filtration and separation applications. However, water transport between interlayers formed by 2D materials cannot be comprehensively described by traditional transport theory because different 2D materials have varying hydrophilicity, which strongly affects water transport. Herein, we build interlayer channels formed by 2D sheets with various hydrophilicities and investigate the pressure-driven water transport via nonequilibrium molecular dynamics simulations. The influence of channel hydrophilicity on water transport is dominant, especially at the nanoscale. To model the water-transport phenomena through channels with various hydrophilicities, we define a new slip length to derive the appropriate equation. By two methods of calculating the slip length based on the simulation results, we validate our derived equation, which predicts the water flux in...

Water Phenomena in PEFCs As the Origin of the Pt Loading Effect: A Comprehensive Modelling Study

The highly prioritized objective of research on polymer electrolyte fuel cells is to make highly performing and stable catalyst layers with drastically reduced platinum loading. Achieving this objective demands an understanding of the impact of composition and porous structure of the electrode layers on the water balance in the cell. Experimental studies 1-3 have shown a marked increase in the resistance to oxygen diffusion when the Pt content of the cathode catalyst layer was lowered 4 . We present a water balance model to explain these trends. Figure 1 illustrates modeling domain and processes considered. The set of 1D continuity and flux equations is formulated and solved for water distribution and fluxes in catalyst layers, diffusion media and flow fields. Model solutions reveal the impact of structure, composition, and operating conditions on the water transport phenomena and performance. Reducing the Pt loading induces a drastic shift of the balance between rates of water production and vaporization. This leads to a build-up of the liquid water pressure in catalyst layer and gas diffusion layer on the cathode side that raises the liquid water accumulation and thereby drastically diminishes the effective oxygen diffusivity. Our model unravels the fine details of this interplay and it helps identify strategies for minimizing the Pt loading without running into this water trap

A mesoscale approach for modeling capillary water absorption and transport phenomena in cementitious materials

This paper proposes a mesoscale approach for simulating moisture transport by capillary action in partly-saturated porous cementitious composites. The modeling approach explicitly accounts for moisture transport through a mesostructure composed of coarse aggregates, surrounding cementitious mortar and interfaces. These latter, namely interface transition zones (ITZs), allow to describe the interaction between aggregates and mortar, and may cause an alternative path for the internal moisture movements. Basic morphology effects of the ITZs are simulated using a ribbon approach. Random spatial distribution of cement particles are stacked in the meso-geometry. Aggregate particles are introduced as randomly perturbed polygons and the moisture transport is modeled as a diffusion problem and solved by means of the finite element method. The proposed constitutive models are based on a proper description of the permeability and pore size distribution which strongly affect the local moisture content. Numerical results at both macro- and mesoscale levels demonstrate the soundness and capability of the proposed approach. The integrated modeling results actually demonstrate the potential of the mesoscale approach and shows the role of the ITZs as an internal interconnected network.

Temperature dependence of water transport phenomenon near MPL in PEFC

Temperature dependence of water transport phenomenon near MPL in PEFC

Evaluation and monitoring of water diffusion into stone porous materials by means of innovative IR thermography techniques

This paper shows the application of two innovative infrared thermography (IRT) methods for the evaluation of water transport phenomena through the outer layers of porous stone materials. An infrared camera measured: (a) the moisture stain due to the water absorption after having spilled a drop on the stone surface and (b) the ”moisture ring” around the damp surface, after the contact between a soaked round sponge and the stone surface. The time of spreading and the geometric shape of the damped area depend on the porosity of the stone material and are useful to characterize the physical stone features. In addition, monitoring the evolution of the moisture ring by IRT allows implementing and optimize the data coming from protocols of water repellent products with data coming from the “contact sponge measures”. Moreover, moisture ring test links IRT and laboratory tests characterizing the transport phenomena of liquid and water vapour in porous building materials. Thirty specimens of marble, calcarenite and sandstone were tested with steady methods (dry index and water absorption by capillarity), that validated the data provided by the two innovative IRT techniques.

Analysis of Oxygen Transport Resistance Components and Water Transport Phenomena with Hydrophilic and Hydrophobic MPL in PEFC

It has been widely accepted that micro-porous layers (MPLs) improve the cell performance by promoting water removal from reaction area in PEFC. Most MPLs are made of carbon black (CB) and hydrophobic polymer (PTFE). However, some recent studies reported that the cell with the hydrophilic MPL with carbon fiber (CF) and ionomer shows better cell performance than that with the conventional hydrophobic MPL in a wide range of humidity conditions (1). In addition, the previous research by the authors suggested a possibility that the hydrophilic CF-MPL promotes water removal from the catalyst layer (CL) (2). This study tried to develop the limiting current method to evaluate the oxygen transport resistances in the CL and in the other parts quantitatively under flooding conditions. Using the developed method, the effects of water on the oxygen transport resistances were compared between with the hydrophobic CB-MPL and with the hydrophilic CF-MPL. Further, microscopic distributions of water in the cross-section at the cathode side MPLs were observed by a freezing method and a cryo-SEM (2). In this study, a small cell with active area of 1.8cm2(0.9cm × 2.0cm) was used because the cell must be frozen and disassembled rapidly for the freezing method. GDLs with two types of MPLs were used at cathode side in experiments: a 10µm thick MPL with CB and hydrophobic PTFE and a 30µm thick MPL with CF and hydrophilic ionomer. These GDLs with MPLs were experimentally made by Asahi Glass Co., Ltd. At anode side, the hydrophobic CB-MPL was used. The catalyst coated membrane (CCM) used in this study were made by W. L. Gore & Associates, Co., Ltd. In this study, the experiments consisted of the cell performance measurements and observations of water distribution in the vicinity of MPL. The freezing method and the cryo-SEM were used for the observation (2). The cell temperature and relative humidity were set at 70°C and 81%RH, respectively. The polarization curves of the cell using the two types of MPLs are compared at 100kPa with O2 21% and at 220kPa with O2 24% in Figure 1. There is little difference in the polarization curves at 100kPa, while at 220kPa the cell voltages with the hydrophilic CF-MPL are higher at high current densities. This result suggests that the CF-MPL suppresses an increase in the concentration overvoltage due to flooding. To clarify the reason for higher voltages with the CF-MPL, we attempted to develop a method to evaluate influence of produced water on oxygen transport resistance which correlates the water transport phenomena. This method was developed by extending the limiting current method (3) for the flooding conditions. Applying criteria to assume similar distributions of produced water and similar oxygen transport resistance made it possible to separate the resistances between inside and outside CL considering the effect of produced water. The oxygen transport resistances separated using the developed method with various limiting currents at some pressures are shown in Figure 2. The horizontal axes represent the criteria for similar transport resistances for (a) outside and (b) inside the CL. Inside the CL (Figure 2(b)), the oxygen transport resistances with the hydrophilic CF-MPL are lower especially at higher current densities. This suggests that the hydrophilic CF-MPL drains produced water from the CL efficiently. Figure 3 shows the water distribution in the vicinity of MPLs at just before limiting current. There is ice layer at the interface between the MPL and the CL in each case, (a) with the hydrophobic CB-MPL and (b) with the hydrophilic CF-MPL. This indicates that improving adhesion of the MPL and the CL is important for suppression of flooding at the interface. Focusing on the hydrophilic CF-MPL, a small amount of water intrudes the pores of the MPL. Further, the CL appears to be filled with less ice with some vacant pores remaining in spite of higher current density. These water distributions correspond to the measured oxygen transport resistance in Figure 2 and the idea that the hydrophilic CF-MPL promotes water removal from the CL. Reference (1) T. Tanuma and S. Kinoshita, J. Electrochem. Soc.,159, B150 (2012). (2) Y.Aoyama, et al., ECS. Trans., 69, 743 (2015). (3) D.R. Baker, et al., J. Electrochem. Soc., 156, B991 (2009). Figure 1

Abrasive Wear Resistance, Mechanical Behaviour, Water Transport Phenomena and Biocorrosion of Epoxy/Femora Biocomposites

Abrasive Wear Resistance, Mechanical Behaviour, Water Transport Phenomena and Biocorrosion of Epoxy/Femora Biocomposites

Analysis of Oxygen Transport Resistance Components and Water Transport Phenomena with Hydrophilic and Hydrophobic MPL in PEFC

This paper investigated the mechanism of water and oxygen transport phenomena in the vicinity of a micro-porous-layer (MPL). The influence of contact firmness between the MPL and a catalyst layer (CL) on the transport was evaluated quantitatively by analyzing oxygen transport resistance components. For the analysis, the limiting current method was extended to flooding conditions. These investigations were conducted with each of hydrophobic and hydrophilic MPLs. With low contact firmness, oxygen transport resistance inside the CL was high; there was ice layer at the MPL/CL interface, observed by the freezing method and cryo-SEM. These results suggested that the residual water at the MPL/CL interface blocks the oxygen transport and increases the oxygen transport resistance in the CL significantly. Furthermore, the analysis of oxygen transport resistance indicated that the hydrophilic MPL composed of carbon fiber has the role of draining condensed water from the CL to the MPL.

Hydration and dehydration cycles in polymer electrolyte fuel cells operated with wet anode and dry cathode feed: A neutron imaging and modeling study

Abstract Proper water management plays an essential role in the performance and durability of Polymer Electrolyte Fuel Cells (PEFCs), but it is challenged by the variety of water transport phenomena that take place in these devices. Previous experimental work has shown the existence of fluctuations between low and high current density levels in PEFCs operated with wet hydrogen and dry air feed. The alternation between both performance states is accompanied by strong changes in the high frequency resistance, suggesting a cyclic hydration and dehydration of the membrane. This peculiar scenario is examined here considering liquid water distributions from neutron imaging and predictions from a 3D two-phase non-isothermal model. The results show that the hydration-dehydration cycles are triggered by the periodic condensation and shedding of liquid water at the anode inlet. The input of liquid water humidifies the anode channel and offsets the membrane dry-out induced by the dry air stream, thus leading to the high-performance state. When liquid water is flushed out of the anode channel, the dehydration process takes over, and the cell comes back to the low-performance state. The predicted amplitude of the current oscillations grows with decreasing hydrogen and increasing air flow rates, in agreement with previous experimental data.

Water transport phenomena through membranes consisting of vertically-aligned double-walled carbon nanotube array

Nanofluidics in CNTs is argumentative though it is theoretically calculated by various reports. It is because only a few of experimental reports are available, and the measured permeability is not so large as that suggested from the theoretical calculations. Also, water motion suppression in the confined space has not been exhibited by flux measurement. The present work explores these yet-unsolved discrepancies using the measurable size membrane of vertically aligned double-walled carbon nanotube array, which is borne with durability and flexibility, and a conventional measurement method is applied to the membranes. Water motion suppression occurs in the CNT confined space significantly, depending on temperature. Additionally, it is confirmed that the obtained permeability correlates to the reported experimental results with regard to the relationship between CNT length and permeability, and the correlation does not agree with permeability calculated from the Hagen-Poiseuille law. These results pose an insight into the inherent water transport characteristics in the CNT confined space.

Water uptake, ionic and hole transport in La0.9Sr0.1ScO3 − δ

The structure of dry and hydrated perovskite La0.9Sr0.1ScO3−δ has been studied by means of X-ray and neutron powder diffraction methods. Preferable positions for oxygen vacancies and deuterons in the oxide have been determined. Thermodynamics of water vapour uptake and transport phenomena have been experimentally investigated at pH2O=0.24atm and pO2=0.18atm in the temperature range from 300 to 950°С. The enthalpy and entropy of hydration reaction have been calculated. The oxidation enthalpy for two possible mechanisms of hole transfer (band conduction and small polaron hopping) have been estimated. The electrical conductivity has been investigated by means of impedance spectroscopy measurements in the temperature range from 500 to 900°С and at the oxygen partial pressures of 10−20atm<pO2<0.21atm. The oxygen surface exchange and diffusion coefficients have been obtained by means of the isotope exchange method with gas phase equilibration in the temperature range of 600–900°С and at the oxygen partial pressure 0.01atm. The dependences of the transference numbers of protons, oxygen ions and holes on external conditions have been determined. The La0.9Sr0.1ScO3−δ oxide was found to be a pure protonic conductor at temperatures below 600°С under reducing conditions.

Optimisation of reverse osmosis based wastewater treatment system for the removal of chlorophenol using genetic algorithms

Reverse osmosis (RO) has found extensive applications in industry as an efficient separation process in comparison with thermal process. In this study, a one-dimensional distributed model based on a wastewater treatment spiral-wound RO system is developed to simulate the transport phenomena of solute and water through the membrane and describe the variation of operating parameters along the x-axis of membrane. The distributed model is tested against experimental data available in the literature derived from a chlorophenol rejection system implemented on a pilot-scale cross-flow RO filtration system with an individual spiral-wound membrane at different operating conditions. The proposed model is then used to carry out an optimisation study using a genetic algorithm (GA). The GA is developed to solve a formulated optimisation problem involving two objective functions of RO wastewater system performance. The model code is written in MATLAB, and the optimisation problem is solved using an optimisation platform written in C++. The objective function is to maximize the solute rejection at different cases of feed concentration and minimize the operating pressure to improve economic aspects. The operating feed flow rate, pressure and temperature are considered as decision variables. The optimisation problem is subjected to a number of upper and lower limits of decision variables, as recommended by the module’s manufacturer, and the constraint of the pressure loss along the membrane length to be within the allowable value. The algorithm developed has yielded a low optimisation execution time and resulted in improved unit performance based on a set of optimal operating conditions.

ガス拡散層の相対透過率による固体高分子形燃料電池内水輸送への影響

It is important to understand liquid water transport phenomena in through-plane direction in an operating polymer electrolyte fuel cell (PEFC) for improving power generation efficiency. As water accumulation affects the mass transport, relative permeability has been investigated as a function of water saturation. However, the values are much different in each model in particular for lower water saturation condition. The purpose of this study is to clarify water transport phenomena and effect of relative permeability of gas diffusion layer (GDL) on water transport phenomena in a PEFC. Three-dimensional mass transfer analysis in a GDL with multiphase mixture model was carried out. Numerical results using two different relative permeability models and experimental results were compared. Liquid water were distributed uniformly in the through-plane direction using Wang's model. Using hussaini's model, much water accumulate at reactive surface. Better results could be obtained using Hussaini's model of the relative permeability for predicting the water distribution.

Transport Phenomena of Water in Molecular Fluidic Channels.

In molecular-level fluidic transport, where the discrete characteristics of a molecular system are not negligible (in contrast to a continuum description), the response of the molecular water system might still be similar to the continuum description if the time and ensemble averages satisfy the ergodic hypothesis and the scale of the average is enough to recover the classical thermodynamic properties. However, even in such cases, the continuum description breaks down on the material interfaces. In short, molecular-level liquid flows exhibit substantially different physics from classical fluid transport theories because of (i) the interface/surface force field, (ii) thermal/velocity slip, (iii) the discreteness of fluid molecules at the interface and (iv) local viscosity. Therefore, in this study, we present the result of our investigations using molecular dynamics (MD) simulations with continuum-based energy equations and check the validity and limitations of the continuum hypothesis. Our study shows that when the continuum description is subjected to the proper treatment of the interface effects via modified boundary conditions, the so-called continuum-based modified-analytical solutions, they can adequately predict nanoscale fluid transport phenomena. The findings in this work have broad effects in overcoming current limitations in modeling/predicting the fluid behaviors of molecular fluidic devices.

Effect of Flow-Field Structure on the Performance of Hydrogen/Bromine Redox Flow Batteries

A hydrogen/bromine regenerative fuel cell involves complex water and heat transport phenomena during charge and discharge that significantly affect the degree of electrolyte dehydration, electrochemical reactions, proton transport, the concentrations of bromide complexes at the hydrogen electrode, etc. Therefore, developing innovative water and heat management schemes is critical to improve the uniformity of key distributions inside a cell as well as to enhance cell performance and durability. In this work, a three-dimensional, transient, two-phase, non-isothermal hydrogen/bromine fuel cell model is developed by rigorously accounting for two-phase transport and various heat generation mechanisms including irreversible heat, entropic heat, and Joule heating. The model is applied to a 25 cm2 cell in order to precisely investigate water transport and thermal aspects under various charge and discharge conditions. A parallel computing methodology is employed to handle large-scale simulations involving millions of grid points. The large-scale simulations are able to provide extensive multidimensional contours of species concentration, temperature, and current density, assisting in identifying optimal water and thermal management strategies based on a typical geometry of a real-scale hydrogen/bromine cell.

Neutron Imaging Detector with Scintillation Light Magnification and Amplification

Neutron imaging is an ideal method to study water transport phenomena in proton exchange membrane fuel cells (PEMFCs). Neutrons readily penetrate aluminum, carbon and platinum, yet have a high sensitivity to hydrogenous materials, including water. In addition, unlike x-rays, neutrons are a non-destructive probe and do not alter the performance of PEMFCs due to irradiation. As such, there have been numerous studies that revealed the heat and mass transport phenomena in the flow fields and gas diffusion layers [1], freeze operation [2], impacts of carbon corrosion [3], and the impact of porosity in thick non-precious metal catalyst layers [4]. The primary limitation of neutron imaging is the achievable spatial and temporal resolutions. Current state of the art spatial resolution is about 20 µm, with a 20 minute image acquisition time. The spatial resolution is primarily limited by the range of the charged particles that are the result of the neutron capture reaction and are used to detect the neutron. This range is of order 5 µm for many common detector schemes. The temporal resolution is limited by the brightness of neutron sources, which are in general many orders of magnitude less bright than synchrotron x-ray sources; thus to have reasonable time resolution conventional neutron imaging requires the use of beam defining apertures that are of order 1 mm for high resolution imaging of PEMFCs, so that one cannot make use of geometric image magnification. We are pursuing three efforts to improve the achievable image spatial resolution and time resolution. The simplest approach to improving the spatial resolution is to place a narrow slit in front of the test section and scan it across the active area. The challenge of this method is to create a narrow, well-defined, completely opaque slit with opening area ~1 µm. KAERI and Pusan National University have devised a Gadox powder filling method that enables creating such slits, enabling imaging with 1 µm resolution [5]. By amplifying the scintillation light and using a high speed camera, it is possible to record individual neutron scintillation events and using a centroid algorithm determine the position of the neutron with high precision (less than 10 µm). The measured through-plane water content of a PEMFC is shown in figure 1 for the present state of both methods. The final effort is the development of a neutron microscope objective based on reflective neutron optics [6]. With a lens, one no longer requires the use of small beam defining apertures and thus the image temporal resolution can increase by at least a factor of 100. We will report on the progress of the first optics to reach 20 µm resolution and discuss the possibility of achieving 1 µm spatial resolution through neutron image magnification. References T.A Trabold et al, “Use of neutron imaging for proton exchange membrane fuel cell (PEMFC) performance analysis and design”, Handbook of fuel cells v. 5, 2009. R Mukundan et al, “Performance of PEM fuel cells at sub-freezing temperatures”, ECS Transactions 11 (1), 543-552, 2007.JD Fairweather et al, “Effects of cathode corrosion on through-plane water transport in proton exchange membrane fuel cells”, JECS 160 (9), F980-F993, 2013.D Spernjak et al, “Water Management in PEM Fuel Cells with Non-Precious Metal Catalyst Electrodes”, 228th ECS Meeting abstracts, p. 1540, 2015.J. Kim et al, “Fabrication and characterization of the source grating for visibility improvement of neutron phase imaging with gratings”, RSI 84(6):063705, 2013.D. Liu et al “Demonstration of achromatic cold-neutron microscope utilizing axisymmetric focusing mirrors”, Applied Physics Letters 102 (18), 183508, 2013. Figure 1 Comparison of the image quality of the current state of the art (a), the slit imaging method with 4 µm resolution (b), and the reconstructed image from centroiding (c). Figure 1

Numerical Simulation of PEMFC Performance Considering Striped Wettability Distribution of GDL

For optimizing the performance of proton exchange membrane fuel cells (PEMFCs), proper water management in the cell is one of the most important issues because liquid water in PEMFCs have a significant impact on the cell performance. If excessive water accumulate in the cell, including that produced by chemical reactions and the humidification of supplied gases, power generation performance will decrease since the transport of the fuel gas will be blocked by the liquid water that has accumulated in the void of a gas diffusion layer (GDL) or a gas flow channel. On the other hand, the drying of the polymer electrolyte membrane (PEM) causes not only a performance decrement due to an increased proton transport resistance, but also a degradation of membrane. Therefore it is very important to understand the water transport in PEMFCs. Some researchers have investigated the water transport phenomena and mass transfer characteristics in the GDL. Utaka and Koresawa have been proposed a novel GDL (Hybrid type GDL, Fig. 1) which has two different wettability to improve the oxygen diffusivity by controlling the water distributions and movement in the GDL, and have examined the effects of the wettability distribution and PTFE content in the hydrophobic region of the GDL on efficient oxygen diffusivity [1]. Additionally, they also have been proposed a novel gas channel with micro-grooves [2]. The cell performance of PEMFC that combined the hybrid GDL and the gas channel with micro-grooves were experimentally investigated in an attempt to improve the power generation of PEMFC. Figure 2 shows the effects of hybrid GDL and novel gas channel on cell performance, and from this figure, the PEMFC combined the hybrid GDL and gas channel with micro-grooves could enhanced the performance under high current density. A three-dimensional numerical model, which includes the gas channels with micro-grooves, GDLs, catalyst layers in both cathode and anode side and PEM, has been developed to investigate the water transport and power generating characteristics. In addition, we investigate the effectiveness of the hybrid GDL to mitigate liquid water saturation under flooding conditions by using our comprehensive model, and compared with experimental results. Numerical result of liquid water distribution at two different wettability region in GDL shown in Fig. 3. Liquid water distribution biased to hydrophilic regions due to the drawing the water from the hydrophobic region into the hydrophilic region. Furthermore, the performance of PEMFC improved by combined the hybrid GDL and novel gas channel with micro-grooves, and discussed quantitatively. Reference [1] R. Koreaswa and Y. Utaka, J. Power Sources, 271, 16 (2014). [2] Y. Utaka, A. Okabe and Y. Omori, J. Power Sources, 279, 533 (2015). Figure 1