Water Evaporation Rate Research Articles

Surface patterned polyvinyl alcohol/CNT hydrogels for sustained solar powered high concentration brine desalination and salt harvesting

Solar-driven interfacial evaporation is an attractive way to achieve water purification. However, high water evaporation rates often result in the precipitation of salt crystals on the surface of the evaporator leading to decay of the evaporation efficiency over time, which makes it difficult to balance high water evaporation rates with salt resistance. Herein, an anisotropic polyvinyl alcohol/CNT hydrogel is constructed by directional freezing and surface patterning. The polymer backbone formed by the polyvinyl alcohol chains interacts with the water clusters to reduce the evaporation enthalpy of water and the absorbed water can be released by squeezing the hydrogels due to the micron-sized vertically aligned pores. More importantly, by designing the structure of the hydrogels surface, the gas–liquid interface of the evaporators can be increased while the growth direction of the salt crystals can be controlled. As a result, the water evaporation rate can be increased from 3.26 kg m-2h−1 to 3.69 kg m-2h−1 under one sun irradiation through surface patterning. After 50 h of continuous operation in 10 wt% NaCl solution under one sun irradiation, the water evaporation rate gradually increases and a large amount of salt collection is collected, which proves its satisfactory salt resistance.

Bioinspired Photothermal Metal-Organic Framework Cocrystal with Ultra-Fast Water Transporting Channels for Solar-Driven Interfacial Water Evaporation.

Herein, a bioinspired metal-organic framework (MOF) cocrystal produced from the co-assembly of a MOF [Ni3(hexaiminobenzene)2, Ni3(HIB)2] and p-chloranils (CHLs) is reported. Because of the 2D conjugation nature and the formation of persistent anion radicals, this cocrystal shows an excellent photothermal property, and is further used as an absorber in solar-driven interfacial water evaporation. The solar-driven interfacial water evaporation rate (4.04 kg m-2 h-1) is among the best compared with those of previously reported photothermal materials. Molecular dynamics simulation results suggested that the rotating of the CHL molecules relative to the MOF planes tuned the pore size to enable the ultra-fast water transporting, and thus ultra-high water transporting rates (1.11 × 1011 and 3.21 × 1011 H2O s-1 channel-1 at 298.2 and 323.0 K, respectively) for layered cocrystal structures, that are much higher than that of aquaporins (≈1.1 × 1010 H2O s-1 channel-1 at 298.2 K), are observed. The superior solar-driven water evaporation performance is thus attributed to the synergistic effect of the ultra-fast water transporting pores together with the excellent photothermal property of the cocrystal. This research provided a biomimetic strategy of rational design and production of charge transfer cocrystals to modulate their pores and photothermal properties for solar-driven interfacial water evaporation.

Towards Sustainable Energy Solutions: Evaluating the Impact of Floating PV Systems in Reducing Water Evaporation and Enhancing Energy Production in Northern Cyprus

Floating photovoltaic systems (FPVSs) are gaining popularity, especially in countries with high population density and abundant solar energy resources. FPVSs provide a variety of advantages, particularly in situations where land is limited. Therefore, the main objective of the study is to evaluate the solar energy potential and investigate the techno-economic perspective of FPVSs at 15 water reservoirs in Northern Cyprus for the first time. Due to the solar radiation variations, solar power generation is uncertain; therefore, precise characterization is required to manage the grid effectively. In this paper, four distribution functions (Johnson SB, pert, Phased Bi-Weibull, and Kumaraswamy) are newly introduced to analyze the characteristics of solar irradiation, expressed by global horizontal irradiation (GHI), at the selected sites. These distribution functions are compared with common distribution functions to assess their suitability. The results demonstrated that the proposed distribution functions, with the exception of Phased Bi-Weibull, outperform the common distribution regarding fitting GHI distribution. Moreover, this work aims to evaluate the effects of floating photovoltaic systems on water evaporation rates at 15 reservoirs. To this aim, five methods were used to estimate the rate of water evaporation based on weather data. Different scenarios of covering the reservoir’s surface with an FPVS were studied and discussed. The findings showed that annual savings at 100% coverage can reach 6.21 × 105 m3 compared to 0 m3 without PV panels. Finally, technical and economic assessment of FPVSs with various scales, floating assemblies, and PV technologies was conducted to determine the optimal system. The results revealed that a floating structure (North orientation-tilt 6°) and bifacial panels produced the maximum performance for the proposed FPVSs at the selected sites. Consequently, it is observed that the percentage of reduction in electricity production from fossil fuel can be varied from 10.19% to 47.21% at 75% FPV occupancy.

Perylene diimide-derived supramolecules-modified graphene sponge as a high-efficiency solar steam generator

Generating steam using solar energy appears to be an effective approach to obtaining clean water, especially from salty water and wastewater, since the sun is a natural and constant source. Compared to many methods, studies in solar steam generation have accelerated due to being highly efficient, sustainable, and low-cost. Graphene sponges (GrSs), possessing structural flexibility and effective photothermal activity, are widely used for this purpose. However, the hydrophobic character of these materials limits their effectiveness in solar steam generators. At this point, we prepared perylene diimide-derived supramolecules (PDI) modified three-dimensional (3D) gradient hydrophobic GrS (PDI/GGrS) as the highly efficient solar thermal converter for the generation of clean water. PDI allowed us to achieve perfect absorption of broad-band sunlight and GGrS facilitated water transport through channels of sponge structure. As a result, PDI/GGrS has achieved a high water evaporation rate of 3.5 kg h−1 m−2 with a superior solar thermal conversion efficiency of up to 90 %. This study can provide new possibilities for harvesting solar energy by producing clean water from seawater, wastewater, and even acidic/alkali solutions.

Remote sensing insights into water allocation and evaporation challenges in the Hirmand River Basin, after the operation of Kamal Khan Dam

Study RegionThe Hirmand River Basin is a vital transboundary river system, that originates in Afghanistan’s Hindu Kush Mountains and flows into the Sistan Depression, and encompassing the Chah Nimeh Reservoirs in Iran and the Godzareh Depression in Afghanistan. Study FocusThe Kamal Khan Dam, constructed on the Hirmand River in Afghanistan, has significantly altered the downstream water direction and distribution between the Chah Nimeh Reservoirs and Godzareh Depression. Utilizing remote sensing techniques, particularly Landsat 8 satellite imagery and the FAO 56 PM as a evaporation retrieval method, the research focuses on evaluating changes in water allocation and evaporation rates in these regions over the past decade. New Hydrological Insights for the RegionThe findings reveal that after operation of the Kamal Khan Dam, water allocation to the Chah Nimeh Reservoirs has drastically decreased, leading to a 54 % reduction in their average area from 2020–2023 compared to the previous years. Conversely, the Godzareh Depression, now receiving the redirected water, has experienced significantly higher evaporation rates, contributing to substantial water losses. These changes underscore the critical need for effective water management strategies to address the escalating water scarcity and hydrological imbalances in this arid region.

Fabrication of Micro/Nanostructured Copper Fibers by Vibration Cutting for Felt-Based Freshwater Purification

Freshwater purification from wasted water and seawater is crucial in addressing the global problem of water scarcity. Porous fiber felt with a micro/nanostructure emerges as an efficient approach for water purification; however, its production usually relies on chemical postprocessing to create micro/nano structures on the fiber surface, which might pollute the environment. This study proposed an ecofriendly method to produce micro/nanostructured copper fiber felt without chemical treatment. First, a new transverse-feeding vibration cutting is proposed to fabricate micro/nanostructured fibers with controllable structure characteristics. Through the sintering of the structured fibers without postprocessing, the fiber felt can be produced in an ecofriendly way and exhibit special wettability and excellent photothermal properties. Felt-based freshwater purification, including oil–water separation and solar-driven seawater desalination, can be realized effectively. Results show an oil–water separation efficiency of > 90% and a high evaporation rate of water of > 1.08 kg m−2 h−1 at 73 mW cm−2 are achieved, demonstrating the application prospect of the produced fiber felt.

Green conversion of waste polyester into few-layer graphene for interfacial solar-driven evaporation and hydroelectric electricity generation

The coupling of solar-driven interfacial evaporation with hydrovoltaic technology is emerged as a hopeful approach to alleviate energy crisis and freshwater shortage. However, constructing low-cost evaporators with high-performance freshwater and electricity co-generation and unveiling the co-generation mechanism remain a grand challenge. Herein, we report the green transformation of waste poly(ε-caprolactone) into graphene through a salt-assisted carbonization strategy and build a flexible bi-functional graphene-based evaporator for freshwater and electricity co-generation. The graphene exhibits a typical wrinkled structure with curved edges and is composed of 7–8 discontinuous layers with rich oxygen-containing groups. The graphene-based evaporator exhibits excellent sunlight absorption (98%), photo-to-thermal conversion property, good water transport ability, low water evaporation enthalpy, and low thermal conductivity of 0.06 W m−1 K−1. The evaporator not only exhibits a notable water evaporation rate (2.92 kg m−2 h−1), but also achieves the maximum output voltage of 310 mV, surpassing many previously reported evaporators/generators. The result of molecular dynamics simulation proves the diffusion difference between H+ and OH− in water and graphene, which eventually leads to the voltage generation. Not only will this work help to improve the upcycling of waste plastics and achieve carbon neutrality, but it will also open an avenue for co-generation of freshwater and electricity.

A perspective view of salt crystallization from solution in porous media: morphology, mechanism, and salt efflorescence.

Salt efflorescence is one of the major hazards to cultural heritages, masonries, and highways etc. It is now generally accepted that damages caused by salt efflorescence are mainly due to continuous cycles of salt crystallization/dissolution or hydration/dehydration in confined spaces. The position where salt efflorescence occurs and its type are closely related to the degree of damages caused by salt efflorescence. It is known that water is the key environmental factor determining the salt crystallization position. But influence of the correlation between water supply and evaporation on the position of salt crystallization is still not clearly understood. In this work, a set of experiments are designed to investigate salt efflorescence in porous matrix. It is found that the types and positions of salt efflorescence have little to do with nucleation, but are mainly governed by crystal growth, which is controlled by the rates of water evaporation, water and salt supply, capillary forces and surface properties of the porous matrices.

Enhanced solar interfacial evaporation through lignin-polyaniline composite coatings on Balsa wood substrates

Solar interfacial evaporation employing wood-derived substrates is increasingly acknowledged as a viable desalination and wastewater treatment technique. This study presents an optimized method that enhances the efficiency of solar interfacial evaporation by applying a coating of lignin-polyaniline composites (EHL-PANI) onto balsa wood substrates. Initial assessments involved comparing evaporators made from various kinds of wood, identifying balsa wood-based photothermal evaporators as the most effective, with an evaporation rate of 1.63 kg·m−2·h−1 and an efficiency of 72.7 %. Photothermal properties were further improved through the chemical oxidation of enzymatic hydrolysis lignin (EHL) with polyaniline, producing a composite with notably high dispersion stability and uniform particle distribution. This modification resulted in reduced particle size and enhanced stability of the polyaniline, which is crucial for boosting photothermal activity. Additionally, the EHL-PANI composites demonstrated exceptional light absorption, exceeding 95 %, and significant photothermal conversion efficiency across a broad wavelength range, attributable to polyaniline's broadband light absorption characteristics. A prototype evaporator, featuring the EHL-PANI coated on a balsa wood substrate, was constructed to assess performance, achieving a water evaporation rate of 2.10 kg·m−2·h−1 and an efficiency of 80.7 % under solar illumination of 1 kW·m−2.

Bifunctional Photothermal Evaporator Based on an MXene/Fe-MOF Collaborative Effect toward Efficient Solar Steam Generation and Simultaneous VOC Removal.

Solar-driven interfacial water evaporation has become one of the most promising approaches to effectively harvesting freshwater, yet the fabrication of high-performance and multifunctional solar interfacial evaporators (SIEs) still remains a huge challenge to date. In this study, a multifunctional MXene and Fe-MOF@cellulose acetate/polyvinylpyrrolidone (MXM@CP) SIE was prepared via a facile "electrospinning and suction filtration deposition" coupling strategy. Thanks to the incorporation of MXene, MXM@CP displayed excellent photothermal conversion performance. Together with the fast water transport channel provided by the porous cellulose acetate electrospinning substrate, a remarkable solar-driven water evaporation property was achieved for MXM@CP, showing a higher water evaporation rate of 1.1 kg m-2 h-1 under one sun irradiation. Moreover, the resultant composite film also exhibited excellent Fenton catalytic activity to effectively degrade volatile organic compounds (VOCs) due to the synergistic effect of the MXene and Fe-based MOF (Fe-MOF). Particularly, a relatively higher degradation rate of 82.8% was acquired for the resulting evaporator toward the benzene contaminant. These results provide new insights into the construction of high-performance and multifunctional SIEs toward clean freshwater collection from the VOC-contaminated water system.

Portable self-powered electrochemical aptasensor for ultrasensitive and real-time detection of microcystin-RR based on hydrovoltaic-photothermal coupling effect

Coupling different energy harvesting technologies to obtain an excellent output signal is essential for the development of high-performance self-powered electrochemical sensors. Herein, a novel hydrovoltaic-photothermal coupling self-powered electrochemical aptasensing platform was designed for sensitive detection of microcystin (MC-RR) with a digital multimeter as a direct visual readout strategy. The straightforward ultrasonic method was employed to synthesize polyaniline (PANI) and bismuth oxybromide (BiOBr) nanosheets, which were then integrated as active components in a hydrovoltaic device. The unique layer structure of two-dimensional (2D) nanomaterials BiOBr can create flexible interlayer spaces to accommodate various ions and water molecules, which was beneficial to construct evaporation-driven channels. Meanwhile, the exceptional photothermal characteristics of polyaniline could accelerate the water evaporation rate, consequently boosting the migration speed of charge carriers and increasing output signal. Moreover, a digital multimeter was connected to the constructed sensor for real-time displaying the output signal. With the assistance of aptamer, a novel self-powered electrochemical aptasensing platform was constructed for sensitive detection of MC-RR. Under optimum conditions, the output signal of the hydrovoltaic-photothermal coupling cell was linearly related to the logarithm of MC-RR concentration in the range of 1 fM to 1 nM with a detection limit of 0.31 fM (S/N = 3). Furthermore, this sensor also exhibited many advantages such as high selectivity, good repeatability and portability. Such novel strategy not only offers a completely new general approach to construct high-performance self-powered devices for the detection of MC-RR, but also provides a new strategy for advancing the miniaturization and field application of self-powered electrochemical sensors.

Combustion synthesis of TiO2/C composites for enhanced photocatalytic H2O2 production and solar steam evaporation efficiency

In this work, a simple combustion method was proposed for the controllable synthesis of TiO2/C composites, which can achieve both the efficient solar water evaporation at the interface and photocatalytic H2O2 production. Structural and morphological characteristic indicated the co-existence of carbon quantum dots and amorphous carbon, which were well distributed on the surface of the TiO2. TiO2/C composites displayed the enhanced visible light absorption and the rapid separation of photogenerated electron-hole pairs. TiO2/C-10 exhibited an excellent photocatalytic H2O2 production activity of 3068.46 μmol/g/h under simulated solar irradiation. Besides, its water evaporation rate reach up to 5.81 kg·m−2·h−1 under the simulated solar irradiation.

Controlled airflow fluctuations for improved performance of mist cooling systems: Enhanced evaporation and thermal comfort

Rising global temperatures and resulting heat stress on people necessitate sustainable outdoor cooling solutions. Mist cooling offers promise, and this work proposes a novel approach: incorporating fluctuating airflows into misting systems. We hypothesize that mist-cooled fluctuating airflows could provide more efficient outdoor cooling for people, for two reasons: 1) Increased turbulence and mixing promoting higher water evaporation rates; 2) dynamic airflow leveraging transient thermal perception for improved comfort.Wind tunnel experiments and numerical simulations support this hypothesis, revealing that fluctuating flow, compared to constant flow with the same average velocity, enhances evaporation. Lower frequencies, higher amplitudes, and profiles with steeper gradients led to higher evaporation rates. These findings assume an idealized domain, excluding natural wind patterns. Furthermore, predictions confirmed that fluctuating flows consistently provide superior thermal comfort compared to constant flows. Fluctuating airflow with misting achieved equivalent comfort at 38% lower energy consumption compared to fluctuating flow without misting and 81% lower compared to constant flow with misting. The proposed technology has the potential to improve outdoor comfort and decrease resource consumption. It is scalable, not complex, and can be implemented into existing systems, though it may face challenges such as increased wear on fan components.

Tree-like 3D GNP-rPN composite structure for solar-thermal evaporation and photocatalytic degradation of antibiotic wastewater

To realize high-yield and long-term purification of wastewater containing antibiotic ciprofloxacin hydrochloride (CIP) and seawater, a tree-like 3D GNP-rPN solar-driven water evaporation and photocatalysis evaporator is developed by preparing and assembling GO/NPDI/PVA (GNP) hydrogel (canopy) and rGO/PU/NPDI (rPN) foam (trunk). The “tree-like” evaporation and photocatalysis evaporator design in this work has the following three characteristics: First of all, graphene oxide (GO) and reduced graphene oxide (rGO) sheets broaden the light absorption range of the photocatalyst perylene imide nanowires (NPDI), which facilitates absorption of more sunlight; secondly, GO and rGO adsorb pollutants in water and provide them to NPDI for catalytic degradation under sunlight irradiation because of their huge specific surface area; thirdly, the excellent photothermal conversion ability of GO and rGO converts solar energy into heat energy, thus facilitating the catalytic degradation of CIP by NPDI. Thanks to the reduced enthalpy of water evaporation by GNP hydrogel, the sufficient top-down water supply, the superior photocatalytic performance of NPDI nanowires, and the efficient solar light absorption and solar-thermal energy conversion of the GO sheets and NPDI nanowires, the resultant GNP-rPN evaporation and photocatalysis system achieves an average water evaporation rate of 2.84 kg m−2 h−1 and a CIP degradation efficiency of 74.04 % within 1 h under 1-sun irradiation. The GNP-rPN system exhibits an optimal degradation efficiency of 74.04 % for a CIP solution with an initial concentration of 10 mg/L within 1 h of irradiation, reaching a degradation efficiency of 96.37 % after 4 h, demonstrating its effectiveness in purifying antibiotic-laden wastewater.

Bioinspired Composite Fabrics with Nanoneedle Structures for High Wicking-Evaporation performance

Achieving ultrafast antigravity water transport and evaporation in high-performance moisture-wicking fabrics remains a significant challenge in textile engineering. In this study, we introduce two novel asymmetric composite fabrics, NN-TS/PET/BS and NS-TS/PET/BS, developed through a straightforward one-step method. These fabrics incorporate different hydrophilic nanostructures—nanoneedles (NN) and nanosheets (NS) of cobalt carbonate—to enhance wicking-evaporation capabilities. The NN-TS/PET/BS fabric exhibited superior unidirectional water transport and evaporation performance, achieving a one-way transport value (R) of up to 330%, an outstanding overall moisture management capacity (OMMC) of 0.87, and a rapid water evaporation rate of 0.5 g h⁻¹, which is 2 and 2.3 times higher than that of NS-TS/PET/BS and Coolmax, respectively. Detailed analyses revealed that the curvature gradients in the nanoneedles significantly enhanced the wetting and evaporation stages, facilitating efficient antigravity water transport. Wear studies confirmed that the NN-TS/PET/BS fabric could swiftly remove sweat from the skin surface, enhancing comfort and performance. These findings offer new perspectives for developing high-performance unidirectional water transport fabrics with broad application potential, including smart textiles, fog harvesting, and wound dressings.

Hierarchical Ti3C2Tx MXene@Honeycomb nanocomposite with high energy efficiency for solar water desalination

The utilization of solar-driven interfacial evaporation holds immense promise in enhancing energy efficiency and establishing sustainable methods for seawater desalination and water purification. While designing the materials to achieve high evaporation efficiency, the tuning of materials with porosity and surface chemistry is very crucial. Novel sustainable materials are of great importance for solar water desalination applications since clean water production is utmost important in the current era. There exists a lack of exploration in modifying the surface wettability states of solar evaporators to expedite the vapor generation rates. In this study, we showcase a hydrophilic Ti3C2Tx MXene-coated carbonized honeycomb (CHC) (Ti3C2Tx MXene@CHC) nanocomposite-based hexagonal-shaped evaporator surface. This is the first-time report on the effective utilization of hierarchical CHC for the preparation of solar absorber comprising of Ti3C2Tx MXene@CHC nanocomposite, particularly for the solar water desalination. The Ti3C2Tx MXene@CHC nanocomposite evaporator achieves an impressive water evaporation rate of 1.6 kg m−2 h−1 with 90% efficiency under 1 sun illumination. The augmented thickness of the water layer in the hydrophilic surface of the Ti3C2Tx MXene@CHC nanocomposite helps in facilitating the rapid escape of water molecules. The relatively elongated contact lines in the hydrophobic region simultaneously ensure substantial water evaporation, significantly enhancing the water desalination process. The Ti3C2Tx MXene@CHC nanocomposite exceeds stringent quality benchmarks, signaling its potential for solar water desalination.

3D structural-engineering evaporator integrating light-space-heat omnibearing regulation

Interfacial solar evaporators designed with sophisticated 3D structure hold the potentiality for ameliorating the evaporation rate through expanding the surface area for evaporation, facilitating water movement, and bolstering air convection. However, the most current 3D evaporators are stalemated of constrained light absorption, circumscribed evaporative surface or thermal dissipation which collectively result in the curtailment of evaporation rate escalation. In this work, an omnibearing convergence of new cup-like 3D solar steam generator (C-3D SSG) based on MoS2/C and PVA materials with integrated coordination of light-space-heat is constructed. The innovative cup-like structural design of C-3D SSG successfully embodies the convergence of light, space, and heat management through the strategic integration of photothermal materials (PTM), substrate materials, and evaporative elements across multiple scales, demonstrating a compelling advancement in light absorption, copious heat diffusion space and prodigious energy-harvesting zone and water evaporation rate enhancement. The omnibearing regulation attains a premium evaporation rate of 3.89 kg m-2h−1 under 1 Sun illumination with recycle energy of 1.71 W. By incorporating the C-3D SSG for practical application, it can function as an evaporator within a cup, thereby enhancing its practical utility. And C-3D SSG with panoramic convergence provides a broad range of research avenues and methodologies for addressing the water crisis and the development of ISSG technology.

Multifunctional HxMoO3-y-MoO2/Carbon Composite Particles for Water Remediation.

Solving a scarcity of freshwater resources is an urgent global challenge by a safe and sustainable approach using renewable energy. We demonstrate the multifunctional catalyst of HxMoO3-y-MoO2/carbon composite particles toward highly efficient water remediation. A one-step mechanochemical reaction successfully upgraded the composites from commercially available MoO3-polypropylene (PP) powders without introducing hydrogen gas. The composite particles exhibited broad light absorption in the UV-visible (Vis)-near-infrared (NIR) region (200-2000 nm), with an optical band-gap narrowing to 1.03 eV. The plasmonic properties of HxMoO3-y-MoO2 allowed a fast water evaporation rate (3.29 kg m-2 h-1) with a photothermal conversion efficiency of 88.8%. In addition, the HxMoO3-y-MoO2 heterojunction dominated wide-spectrum activity under Vis and NIR light irradiation, up to 3 orders of magnitude higher than pristine MoO3 in the photocatalytic degradation of azo-dye pollutants. Furthermore, the byproduct carbon with abundant oxygen-containing groups efficiently eliminated water pollutants as a Brønsted acid catalyst and performed exceptional adsorption capacities of heavy metal ions in the dark.

Numerical Modeling of Water Transport in a Microporous Layer-Coated Porous Transport Layer for a Polymer Electrolyte Membrane Water Electrolyzer with an Interdigitated Flow Field for Internal Gas-Liquid Separation

A novel design for interdigitated flow fields in polymer electrolyte membrane electrolyzers has been developed for both ground and space applications. This design separates oxygen and liquid water internally, eliminating the need for water circulators to remove bubbles and external gas-liquid separators with buoyancy. The capillary pressure in the hydrophobic microporous layer (MPL) of the anode porous transport layer facilitates internal separation of oxygen gas and pressurized liquid water. A finite element model (COMSOL Multiphysics) simulates water transport in the MPL, while electrochemical impedance spectra determine the electrochemical kinetic parameters for the model. The model takes into account the oxygen bubble coverage of the cathode, liquid water saturation in the MPL, and the current ratio between liquid water and water vapor at the MPL-cathode layer interface. The vapor from liquid water in the MPL is modeled to mix with oxygen for diffusion. A volumetric water evaporation rate as a linear function of liquid water saturation in the MPL is assumed, where the rate constant is estimated from vapor permeation tests.

Numerical Modeling of Water Transport in a Microporous Layer-Coated Porous Transport Layer for a Polymer Electrolyte Membrane Water Electrolyzer with an Interdigitated Flow Field for Internal Gas-Liquid Separation

A novel design for interdigitated flow fields in polymer electrolyte membrane electrolyzers has been developed for both ground and space applications. This design separates oxygen and liquid water internally, eliminating the need for water circulators to remove bubbles and external gas-liquid separators with buoyancy. The capillary pressure in the hydrophobic microporous layer (MPL) of the anode porous transport layer facilitates internal separation of oxygen gas and pressurized liquid water. A finite element model (COMSOL Multiphysics) simulates water transport in the MPL, while electrochemical impedance spectra determine the electrochemical kinetic parameters for the model. The model takes into account the oxygen bubble coverage of the cathode, liquid water saturation in the MPL, and the current ratio between liquid water and water vapor at the MPL-cathode layer interface. The vapor from liquid water in the MPL is modeled to mix with oxygen for diffusion. A volumetric water evaporation rate as a linear function of liquid water saturation in the MPL is assumed, where the rate constant is estimated from vapor permeation tests.