Water Production Rate Research Articles

Enlargement of depressions on comet 81P/Wild 2: Constraints based on 30-year cometary activity in the inner Solar System

The Stardust flyby mission to Jupiter-family comet (JFC) 81P/Wild 2 (hereafter, 81P) captured its dense quasicircular depressions. The formation mechanism behind these depressions remains a subject of debate. We aim to study how cometary activity contributed to the formation and enlargement of these depressions by analyzing Stardust flyby images and ground-based observation data. We calculated the time-dependent water production rate of 81P inside the snow line ($<$3 au) and compared it with the observational data. In addition, we estimated the fallback debris mass using an observation-based model, where a dust ejection from 81P was considered to reproduce ground-based observations of the dust tail. We compared the total excavated volume of water and dust with the total depression volume derived, using the 81P shape model. We find that the total excavated volume after 81P was injected into the inner Solar System accounts for up to only 30 % of the depression volume. This suggests that a large portion ($>$70 %) of the depressions had already existed before the comet was injected into the current orbit. In addition, we estimated the dust-to-ice mass ratio for 81P to be 2--14. We suggest that most depressions observed for 81P were formed in their source regions.

Assessing the potential of geothermal energy in Cambrian complexes for renewable energy transition in Lithuania

Several depleted Cambrian oil fields in Lithuania, with water-cuts reaching 99 %, present promising opportunities for geothermal energy utilization. This study focused on Lithuania’s Cambrian reservoir complex, which has the highest water production rates. The study aimed to explore the advantages of horizontal wells, a technology not previously employed for geothermal production in Lithuania, over traditional vertical wells. To optimize field development, various scenarios were evaluated using mechanistic models, with insights subsequently applied to real field conditions. The results from the mechanistic model demonstrated that horizontal wells outperform vertical wells in both water production and power generation. Furthermore, increasing fracture intensity was shown to enhance water output and power generation by operating the wells at pressures above fracture propagation, facilitating re-injection. However, the study also emphasized the importance of thorough reservoir characterization and modeling to account for geological complexities and improve production outcomes. In conclusion, the research underscores that horizontal wells offer several advantages over vertical wells for geothermal energy production. These include increased water production, higher power generation, reduced drilling costs, and enhanced operational efficiency. These benefits align with technological advancements observed in the hydrocarbon industry, making horizontal wells a viable solution for maximizing geothermal energy potential in Lithuania’s depleted oil and gas fields.

Modeling of comet water production. I. Sensitivity to macro- and micro-model parameters

This study investigates the impact of microscopic and macroscopic cometary surface properties on water production variations with heliocentric distance, focusing on dust layer thickness, grain size, nucleus shape, and spin axis orientation. We employed a two-layer thermophysical model to calculate effective gas production, incorporating a dust layer of porous aggregates of submillimeter- and millimeter-sized grains. The model includes radiative thermal conductivity and permeability for volatile diffusion and considers dust layer evolution and tensile strength. We examined different cometary nucleus shape models based on spacecraft observations and calculated power-law exponents for water production rates as functions of heliocentric distance. A two-layer outgassing model with fixed layer properties showed minimal qualitative differences from a simpler water ice sublimation model. The study reaffirms the critical role of the spin axis inclination and illuminated cross-section variation with the heliocentric distance in gas production. Using 67P/Churyumov-Gerasimenko's orbital parameters, the study demonstrates that dust accumulation and layer growth significantly alter production rate exponents. Additionally, considering tensile strength in a homogeneous spherical nucleus model revealed the potential for local dust crust removal near perihelion. Macroscopic properties such as nucleus shape and spin axis orientation significantly influence water production rate variations with heliocentric distance. Microscopic surface characteristics and dust layer growth also play crucial roles in cometary activity. Incorporating tensile strength and dust removal mechanisms into models provides a more accurate representation of comet activity, particularly near perihelion. This refined model enhances our understanding of comet outgassing, highlighting the importance of detailed surface property data for an accurate interpretation of observations.

An Interpretation Method of Gas–Water Two-Phase Production Profile in High-Temperature and High-Pressure Vertical Wells Based on Drift-Flux Model

With the increasing demand for oil and gas, the depth of some vertical gas wells can reach 6000 m. At this time, the downhole fluid is in a state of high temperature and pressure, and interpretation of the production logging output profile faces the problem of inaccurate production calculations and difficulty judging the water-producing layer. The drift-flux model is usually used to calculate the gas–water two-phase flow. The drift-flux model is widely used to describe the two-phase flow in pipelines and wells because of its accuracy and simplicity. The constitutive correlations used in drift-flux models, which specify the relative motion between phases, have been extensively studied. However, most of the correlations are only extended by laboratory data of small pipe diameters at standard temperature and pressure and do not apply to high-temperature and high-pressure large-diameter gas wells. Therefore, we improved the distribution coefficient and drift velocity of drift-flux correlations in this study for high-temperature and high-pressure gas wells with large pipe diameters. Therefore, this study improved the distribution coefficient and drift velocity of the drift-flux correlations for high-temperature and high-pressure gas wells with large pipe diameters. In practical application, the coincidence rates of gas production and water production calculated by the new drift-flux model were 12.68% and 19.39%, respectively. For high-temperature and high-pressure deep wells, the measurement errors of production logging instruments are significant, and surface laboratory pipelines are challenging to configure and equip with actual high-temperature and high-pressure conditions. Therefore, this study used the method of numerical simulation to study the flow characteristics of the two phases of high-temperature and high-pressure gas and water to provide a basis for identifying the water layer. Combined with the proposed drift-flux correlations and the new method of determining the water-producing layer, a new method of production profile interpretation of high-temperature and high-pressure gas wells is obtained.

Revisiting the Gas Diffusion Layer Water Inventory - from Micro to Macro Scale for Modern GDLs

Significant progress has been made over the last decade in improving Polymer Electrolyte Membrane fuel cells (PEMFC), resulting in usable current densities of up to 3.0 A/cm². Specifically for high current density values, it is important to maintain a well-balanced water inventory inside the fuel cell, particularly within the GDL, to prevent flooding of the porous material by excess product water and maintain high permeability for reactant gases. Twenty years ago, several authors conducted research [1,2,3,4] to enhance the modelling of permeability and wetting behavior of gas diffusion layers (GDLs) for PEMFC models. However, the standard Leverett J-function model [5], which was originally developed for porous rocks, remains the default description of saturation in many macro scale fuel cell models. Additionally, the latest GDL materials are much thinner and technologically advanced compared to that time. Thus, this work aims to model the water saturation and permeability of gases in modern GDLs using various simulation methods starting from the micro scale (GeoDict, Pore-Network-Modelling (PNM)). The micro-scale simulations are based on high-resolution X-ray scans of the GDL structure. These scans are analyzed and reconstructed with GeoDict to create digital twins that perform statistically identically and allow for virtual material modifications. Parametric studies for various local operating conditions are then performed using these twins, including e.g. different compression rates, temperatures, water production rates, and gas velocities. These simulations provide insight into the behavior of water saturation within the GDL structure and its influence on the diffusion of oxygen and hydrogen towards the catalyst layer. PNM modelling is employed to ensure the representativeness of the results regarding the macro-scale behavior of the porous material. Using the knowledge gained from the microstructure simulations, the simple Leverett J-function will be benchmarked. Depending on the results, ways to improve the J-function parameters or devising a new macro-scale functional description of the GDL water saturation and the resulting gas diffusion properties of the GDL will be explored.This work has received financial support by the German Federal Ministry for Digital and Transport within the GALLIA project (NIP II, 03B10114D).Citation:[1] Gostick, Jeffrey T., et al. "Capillary pressure and hydrophilic porosity in gas diffusion layers for polymer electrolyte fuel cells." Journal of power sources 156.2 (2006): 375-387.[2] Kumbur, E. C., K. V. Sharp, and M. M. Mench. "On the effectiveness of Leverett approach for describing the water transport in fuel cell diffusion media." Journal of Power Sources 168.2 (2007): 356-368.[3] Kumbur EC, Sharp KV, Mench MM. Validated Leverett approach for multiphase flow in PEFC diffusion media. J Electrochem Soc 2007;154. https://doi.org/10.1149/1.2784283.[4] Sarkezi-Selsky, Patrick, et al. "Lattice Boltzmann simulation of liquid water transport in gas diffusion layers of proton exchange membrane fuel cells: Parametric studies on capillary hysteresis." Journal of Power Sources 535 (2022): 231381. [5] Leverett, MoC. "Capillary behavior in porous solids." Transactions of the AIME 142.01 (1941): 152-169.

Effects of Selected Fuel Cell Operating Conditions on the Distribution of Liquid Water in the Cathode Gas Diffusion Layer

Effective water management is required to enable polymer electrolyte fuel cells (PEFCs) to operate efficiently, particularly at the high current densities needed to make them relevant for transportation and stationary applications. The presence of liquid water can influence the performance of a PEFC when the rate of water production exceeds the rate of water removal [1]. More specifically, accumulation of water within the cell becomes problematic when the pores within the gas diffusion layer (GDL) become filled, resulting in restriction of the transport of reactants to the catalyst layer [2]. Identifying operational conditions that minimize mass transport losses associated with excess water accumulation is crucial for improving the performance of PEFCs, especially at high current densities. Additionally, GDL design plays an important role in reducing mass transport losses, with thermal conductivity being a key factor influencing the distribution of liquid water.In this work, miniaturized fuel cells were operated under various conditions and imaged in-operando using X-ray Computed Tomography (XCT) [3]. This imaging technique facilitates the evaluation of the distribution of liquid water at steady state over a range of operational conditions. The influence of current density on liquid water distribution was assessed at selected cell temperatures between 40°C and 70°C. The results of this study showed high saturations under both the land and the channel regions at 50 °C. However, the channels appeared to be dry at 70 °C, with liquid water present only under the lands. These data were compared to predictions generated using a one-dimensional (1-D) model of the through-plane GDL, which considers specific operating conditions and GDL characteristics, such as thermal conductivity [4]. These results demonstrate that the 1-D model can be used to predict the presence or absence of liquid water within the GDL (and, by extension, PEFC performance) under a broad range of operating conditions. Hence, the 1-D model may be useful for focusing future laboratory investigations. Keywords – operando, X-ray tomographic microscopy, GDL, water visualization Acknowledgement Funding for this research was provided by the Natural Sciences and Engineering Research Council of Canada, Ballard Power Systems, Simon Fraser University, Canada Foundation for Innovation, British Columbia Knowledge Development Fund, and Canada Research Chairs.

Enhancement of Liquid Water and Oxygen Transport By Partially Hydrophilic Mpls in a PEFC

Management of produced water is extremely important to increase the output of PEFCs. Several methods have been investigated to improve the ability to manage liquid water transport by partially adding hydrophilicity to hydrophobic MPLs. In this study, we focused on MPLs coated with a hydrophilic layer(1). By separating the oxygen transport resistance inside and outside the catalyst layer (CL), we analyzed the effect of condensed water in the cell on the oxygen transport phenomenon, and aimed to provide guidelines for the production of MPLs for further power enhancement.A mixture of carbon black: Li-400 (made by DENKA CO.) and Nafion dispersion liquid in a solvent consisting of pure water and ethanol was coated on the MPL side of the gas diffusion layer: 28BC (made by SGL CO.) and allowed to dry to produce the hydrophilic layer. The ratio of carbon black and Nafion in the hydrophilic layer was 10 : 1, and the thickness was about 5 μm.In this study, active area of the cell was 1.8 cm2 (0.9 cm × 2.0 cm). The MPL on the anode side was 28BC and the cathode side was 28BC with a hydrophilic layer applied. The anode side was supplied with hydrogen, and the cathode side was supplied with a mixed gas of oxygen and nitrogen. The gas flow rates were 500 sccm for the anode and 4000 sccm for the cathode. Experiments were conducted at a cell temperature of 35°C with supplied gases of 81% RH. The catalyst coated membrane was produced by Japan Gore-Tex Inc.The oxygen transport resistances were measured by using the limiting current method(2). Inside the CL (pressure independence), it was assumed that the water production rate dominates the water accumulation, which is proportional to current densities. Outside the CL (pressure dependence), it was assumed that the product of total pressure and current density determined the component of oxygen transport resistance. Based on this assumption, the division of oxygen transport resistance was determined by a least square error calculation of actual total oxygen transport resistances and theoretical values(2). This experiment was conducted with different pressure (100 kPa, 140 kPa, 180 kPa), and different oxygen concentration (1%, 2%, 4%, 6%, 8%, 12%, 15%, 18%, 21%).Figure 1 shows the results of oxygen transport resistance in each inside and outside CL. Here, I Lim is limiting current density, and R P (Figure 1 (a)) and R NP (Figure 1 (b)) are pressure-dependent or independent oxygen transport resistances, respectively. These corresponds to the oxygen transport resistance outside and inside the CL. The MPL-1 is 28BC and the MPL-2 is 28BC with a hydrophilic layer applied. In Figure 1(a), the R P of MPL-2 is larger by the hydrophilic layer, and the tendency of change is similar: the R P increases from the low current density region. This shows that the effect of the hydrophilic layer on condensed water is negligible. In Figure 1(b), the R NP of MPL-2 is kept smaller in the low current density region, while it is slightly smaller than that of MPL-1 in the medium and high current density regions. This suggests that condensed water is efficiently sucked out of the CL in the low current density region, but the ability of water removal is insufficient in the medium and high current density regions. The condensed water may be retained in the hydrophilic layer due to its strong hydrophilicity.In this study, the oxygen transport resistance was separated based on the pressure dependence, allowing quantitative investigation of mass transport phenomena inside the cell. The analysis suggested the improvement of water removal ability from the CL by adding the hydrophilic layer to the MPL. We try to apply adding carbon nanotubes to the MPL for further improvement of the ability of water management.Reference(1) T. Kitahara, et al., Transactions of the JSME (B) (in Japanese), 78-794, 1849 (2012).(2) Y. Iizuka, et al, J. Electrochem. Soc., 169-12, 124510 (2022). Figure 1

A High‐Efficiency System for Long‐Term Salinity‐Gradient Energy Harvesting and Simultaneous Solar Steam Generation

AbstractThe vast energy stored in the ocean, which receives an average solar power of ≈60 000 TW per year, surpasses human energy consumption by three orders of magnitude. Harnessing even a small fraction of it holds great promise in addressing global energy and water crises. Here, an integrated device that achieves unprecedented power density up to 1.1 W m−2 with excellent stability through a salinity concentration gradient induced by solar evaporation, while simultaneously producing clean water at a rate of 1.25 kg m−2 h−1 under one sun irradiation is presented. The remarkable electricity generation capability stems from the unique interlayer structure of polyaniline‐graphene oxide‐MnO2 (PANI@GO/MnO2) electrodes, enabling the recovery of electrochemical potentials from a wide range of ion salinity concentrations within the device and the additional Donnan potential generated by the anion‐exchange membrane. Furthermore, periodic flipping of the device effectively reactivates the electrodes and suppresses salt accumulation, enabling long‐term operation. Notably, a prototype device of 8 × 25 cm2 exhibits a short‐circuit current of 10 mA and an open‐circuit voltage of 10.2 V, as well as a clean water production rate of 24.8 g per hour. These findings shed light on the reliable technology for power and freshwater supply in marine environments.

Effect of Isotropic and Anisotropic Permeability on Gas Production Behavior of Site NGHP-01-10D in Krishna-Godavari Basin

This study reports an investigation into both isotropic and anisotropic permeability effects on gas production behavior during depressurization-induced natural gas hydrate dissociation at site NGHP-01-10D in the Krishna-Godavari basin. Numerical simulations were performed on a reservoir-scale model incorporating a single vertical well, examining different scenarios of permeability ratios (rrz). The investigation assessed gas and water production rates, cumulative production volumes, the gas-to-water ratio, and the spatial distribution of reservoir parameters throughout a production duration of 3 years. The findings indicate that permeability anisotropy has a substantial impact on hydrate dissociation and gas recovery. For rrz > 1, horizontal pressure propagation was promoted and gas production increased. For example, at t = 1100 days, the total gas production improved from 7.88 × 105 ST m3 for rrz = 1 to 55.9 × 105 ST m3 for rrz = 10. For rrz < 1, vertical pressure propagation resulted in higher water production with concomitantly lower rates of gas production rates. Spatial distribution analysis revealed that higher rrz values led to more extensive radial propagation of pressure drop, temperature decrease, gas saturation increase, and hydrate dissociation. The study concludes that higher horizontal permeability enhances depressurization effects, resulting in higher gas production rates and more favorable gas-to-water ratios.

Siphon-based scalable and salt-resistant multistage thermal desalination system

Recent advances in thermal localization-based passive solar desalination provide a great opportunity for the economical generation of freshwater, particularly in regions with insufficient energy and water infrastructure. Yet, the capillary-assisted passive desalination systems with a high-water productivity flux (measured in Lm−2 h−1) suffer from the issue of performance degradation due to salt accumulation and the inability to be scaled up. In this work, we propose siphon-based supply of saline water over the evaporator that enables scale up of the desalination system to a size significantly higher than the capillary rise height of the hydrophilic evaporator while preventing salt accumulation on the evaporator. The composite siphon comprises insulating fabric wick and a metallic grooved surface for localizing heat to evaporate a thin layer of saline liquid over the evaporator. We perform heat and mass transfer analysis to show that the thermal-to-vapor efficiency depends on the inlet mass flow rate and air gap between the evaporator and the condenser. We propose a methodology to passively control the mass flow rate to maximize the thermal to vapor efficiency at different input heat flux and initial concentration of the brine. A grooved condenser avoids mixing of brine and the freshwater, even at air gaps as low as 2 mm. A siphon-assisted 10-stage desalination system with a footprint area 15 cm × 15 cm and an air gap of 2 mm is shown to have a high water productivity flux of ∼5.73 Lm−2 h−1 from 3.5 wt% saline water at an applied heat flux 1000 W/m2, which increases to a record high distillate flux of ∼6.23 Lm−2 h−1 and thermal to water collection efficiency of ∼423 % for a 15-stage system. The ability of the desalination system to maintain a high-water productivity flux even when the evaporator area is increased by 4 times demonstrates its scalability to achieve higher desalinated water productivity rate.

Application of batch reverse osmosis as an appropriate technology for inland desalination: Design, modeling, and operating strategies

Despite the recent development of desalination, water scarcity problems in rural areas with insufficient infrastructure cannot be easily resolved. Although batch reverse osmosis (BRO), with its compact design and high second-law efficiency, presents a promising solution for low-energy desalination, the implementation of BRO in rural or energy-deficient regions remains challenging. This study suggests a novel concept of BRO as an appropriate technology (BRO-AT) powered by alternative energy sources, particularly livestock, aiming to achieve high recovery and permeate flux without external electricity. To effectively utilize the BRO-AT, two operating strategies, center supply and village-sharing, are proposed according to local livestock availability. Livestock working schedules were considered to analyze the performance of BRO-AT practically. In high recovery and large permeate flux cases, maximum recovery and permeate flux reached 0.9165 and 3.72 m3/d, respectively. Average recoveries of 0.8296 and 0.6937, and water production rates of 1.15 m3/d and 0.96 m3/d, were achieved using the center supply and village-sharing methods, respectively. This analysis demonstrates the feasibility of BRO-AT for rural regions and highlights the importance of understanding the dynamic characteristics of alternative power sources. The findings provide design and operation guidelines for BRO-AT, offering insights for future utilization and application in energy-limited areas.

Green hydrogen production from thermoelectric condensation of ambient moist air

As the world transitions towards reducing carbon emissions, green hydrogen produced through solar-powered alkaline water electrolysis (AWE) presents a promising eco-friendly fuel option. In response to the challenges caused by global warming, including air moisture saturation leading to unbalanced rainfall, flooding, concern for freshwater depletion and the limited availability of water and energy sources in arid regions. The present study introduces a novel method of integrating thermoelectric water condenser (TEWC) and AWE for green hydrogen production in remote and arid regions where both the water and the conventional energy sources are scarce. Numerical simulations of the present study show that the impact of relative humidity, temperature, and air flow rate significantly affect water condensation, energy requirement, and hydrogen production. The TEWC and AWE models showed excellent agreement with the experimental data. TEWC model reveled that the highest water production rate of 1.50 kg/(m2h) is achieved at ambient air temperature of 308 K and relative humidity of 80%. Furthermore, increasing the moist air flow from 1 m/s to 2 m/s results in a 47.5% increase in water production rate. The AWE model showed that cell's performance improved with higher temperatures, lower electrode-separator gap, and overpotentials. The hydrogen evolution rate reached a maximum of 5.2 kg/(m2h) at current density of 1.4 A/cm2 and potential of 3.96 V. By optimizing the TEWC and AWE systems the integrated method proved to be an efficient way of converting moist air into green hydrogen using solar energy, making it a viable and sustainable setup in remote arid regions.

Study on heat and mass transfer behavior of coupled electrochemical reaction in porous structure of proton exchange membrane fuel cell

Proton exchange membrane fuel cell (PEMFC) is widely used in transportation, aviation and energy storage due to its unique advantages. Improving the performance of fuel cells depends largely on effective hydrothermal management. In this work, a multi-physical field coupling model based on the lattice Boltzmann method (LBM) is established to analyze the oxygen transport, liquid water transport, heat transfer and electrochemical reaction, mainly considering the difference between the overpotential of the cell and the surface wettability of the structure. The results show that the overpotential is closely related to the reaction process. The rate of water production is significantly accelerated by increasing the overpotential, and the breakage and merging of water clusters are observed. The increase of overpotential will lead to more energy loss in the form of heat, thus increasing the heat production. Enhancing the hydrophobicity of the structure has a positive effect on the performance of the fuel cell, and the possibility of local hot spots in the low-hydrophobic structure is greater. It is feasible to improve water management and fuel cell performance through wettability design.

SOME FEATURES OF CONSTRUCTING DISPLACEMENT CHARACTERISTICS AND WATERING DYNAMICS

The term «displacement characteristic» (DCh) was first proposed by D. A. Efros in 1959 to indicate the dependence of the accumulated oil withdrawal on the accumulated liquid withdrawal. Subsequently, DChfound wide application in the analysis of oil field development. Many authors proposed various modifications of the DCh coordinates, but directactual measurements of development parameters were always used - annual, accumulated measurements of oil, liquid, water production, water cut, liquid, oil, and water flow rates. Characteristics of oil displacement are called graphical dependences of accumulated oil production on accumulated or current values of liquid or water production, constructed based on actual data. With the help of cold water, three tasks were solved: assessment of recoverable oil reserves, calculation of the technological effect of geological and technical measures, and calculation of technological development indicators. But the main condition for application was the immutability of the development system.Recently, dependences that use parameters such as selection from geological or recoverable oil reserves have come to be classified as chemical dependencies. These dependencies have nothing to do with DCh. Justification of geological and recoverable oil reserves is an independent task; moreover, with the help of chemical recovery, recoverable reserves are found under the existing development system. Against the background of such a confusion of concepts, the definition of the concept of «standard» chemicals is introduced, which has no real meaning for an oil development facility.The dynamics of water cut refers to the change in water cut over time, for example, depending on the time of development of reserves, geological or recoverable. The dynamics of watering in this case has nothing to do with the cold water.The dry period is of great importance when developing an oil field. With the same finaloil recovery, the longer the water-free period, the better the economic indicators.Using the Buckley-Leverett function todetermine water cut is only possible when the flow is two-phase, oil and water. It is impossible to determine the anhydrous period using the Buckley-Leverett function, since it does not exist, therefore, constructing the dynamics of water supply only based on this function is incorrect.When conducting laboratory experiments on core material, in which the heterogeneity compared to the formation is minimal and can be identified with a one-dimensional flow, the anhydrous period is significant and reaches from 0.74 to 0.94 units. of the total volume of displaced oil.For a single-layer field, where there is only one homogeneous layer, the heterogeneity is greater than for the core, but less than for a heterogeneous development object. We can talk about an analogue of a two-dimensional flow with some degree of convention.Considering that these are not laboratory studies, where measurements are carried out more accurately, but production ones, the low-water-cut period (up to 10 %) is 0.4 of the total oil production from wells with simultaneous commissioning of wells. If the wells were commissioned at different periods of time, as is always the case in fields, then the dynamics of water supply are completely different, and water supply begins earlier than when all wells are commissioned simultaneously.

A robust photoelectrothermal evaporator with hierarchical NiCo2S4 nanowires grown on nickel foam for a high rate of clean water production

Interfacial solar steam generation (ISSG) stands as a promising technology in addressing global water scarcity, stemming from reasons like global warming and population growth. Despite its potential, ISSG faces challenges due to varying weather conditions and solar intensity fluctuations. To overcome these limitations, a novel approach by integrating photothermal and electrothermal Joule-heating effects is introduced in this study for a high-efficiency and salt-resistant all-weather, all-day seawater desalination. Hierarchical NiCo2S4 nanowires are fabricated on a Ni-foam (NCNNF) using a facile two-step hydrothermal method. Under photothermal evaporation, the NCNNF evaporator produces an evaporation rate of 1.57 ± 0.08 kg m−2 h−1 with an evaporation efficiency of 77 % under 1sun illumination with good anti-fouling ability. In a simple water desalination setup, the surface temperature of the evaporator in a wet state reaches ∼63.5 ± 0.25 °C within 10 min by applying an input voltage of 1 V and 1sun irradiation condition, yielding an outstanding evaporation rate of 21.3 ± 3.6 kg m−2 h−1 and evaporation efficiency of 80 %. The proposed evaporation device can resist salt accumulation on the evaporator surface in long-term operations. The present results would be utilized in developing high-performance Joule-heating assisted solar water evaporation devices, especially for all-day, all-weather desalination to produce clean potable water.

COMPARATIVE PERFORMANCE ANALYSIS OF SOLAR STILL WITH AND WITHOUT BASIN LINE WITH BLACK POLYTHENE FILM

Since a solar still's optimal performance is crucial, improvements to both its component designs and environmental factors have received attention. Thus, the focus of this study was the solar still basin. First, a black polythene film was used to line the basin of a planned solar still. The yield of this method was assessed, and then the black polythene film was taken out of the basin and another assessment was made. Hourly measurements of the ambient, glass, basin, and solar intensity as well as the distilled water were made in each case. The experiments' results showed that the temperature of the environment, the glass, and the water in the solar still's basin all increased in tandem with the sun's intensity. The solar still's production rose by 9.1 % per day on average when 0.15 mm black polythene film was used to line the basin. The study confirms that using black polythene film into solar still designs provides a workable and effective way to increase potable water production rates.

Analysis of characteristics of seawater desalination-solar chimney power plant under double-layer collector

To improve the output characteristics of seawater desalination-solar chimney power plants, enrich the theoretical research basis and promote its commercial application, this paper introduces the concept of multilayer flow channel, establishes four new types of multilayer collector flow channel, and constructs the corresponding heat and mass transfer mathematical models, revealing the mechanism of the influence of different flow channel and structural parameters on the system performance. The results showed that the surround-flow system extended the heat absorption time of the airflow, had two thermal storage layers, and had the best performance. The daily average power generation was 43.3 kW, and the average water production rate was 87.2 g/(h·m2), which was 132.8 % and 91.2 % higher than the traditional type’s, respectively, but had the longest start-up time. For the surround-flow system, the main reason for the flow loss increasing is swirling regions below the inlet and the transition section caused by the structure itself. Both the inlet width increasing and the roof’s inclination angle decreasing can increase power generation, with little impact on water production. Corner width increasing results in a significant decrease in water production, with little impact on power generation. The determination of structural parameters should also consider operational costs.

Multifunctional biomass-based solar evaporator with enhanced sterilization performance for solar-driven clean water evaporation

Solar-driven interfacial evaporation presents an important technology in dealing with the global freshwater crisis due to its highly effective solar-to-vapor conversion, minimal environmental impact, and off-grid application. However, the high material cost, complex fabrication process, and lack of effective sterilization limit its scaled-up application. Herein, we demonstrate an efficient multi-functional, biomass-based (MBB) photothermal evaporator using CuO nanoparticle-modified, carbonized peanut shells in a low-cost and scabble way. With highly efficient solar absorption, localized heating, and water transport, the MBB photothermal evaporator achieved a ∼ 91.1 % solar-to-vapor efficiency under sunlight illumination with a clean water production rate of 1.46 kg m−2 h−1. A similar evaporation rate of 1.41 kg m−2 h−1 was obtained directly from wastewater or seawater with a wide range of pH (2–14). The experiments showed that the collected water is relatively clean with complete removal of Escherichia coli and Staphylococcus aureus by damaging bacterial cell walls. 99 % of methylene blue and rhodamine B can also be effectively removed, benefiting from the formation of chelating and hydrogen bonds with the OH groups on the surface of MBB. This research provides a new environmentally sustainable photothermal evaporator for water purification, specifically designed to benefit economically stressed communities.

Comparative study of kernel- and deep learning-based proxy models for nonlinearly constrained life-cycle production optimization

This study presents a comparative study for the application of deep learning–based and kernel-based proxy models in hydrocarbon production optimization with nonlinear constraints, comparing their performance against high-fidelity simulators (HFS) in terms of computational efficiency and the quality of the results achieved. One of the proxy models employed is referred to as embed to control and observe (E2CO), a deep learning–based model. The other model is a kernel-based proxy model known as least-squares support-vector regression (LS-SVR). Both proxy models can predict production/injection outputs for each well. We use the sequential quadratic programming (SQP) method for nonlinearly constrained production optimization. Our optimization objective revolves around the net present value (NPV), while the nonlinear state constraints involve field liquid production rate (FLPR) and field water production rate (FWPR). NPV, FLPR, and FWPR are estimated using two different types of proxy models. The gradient of the objective function and the Jacobian matrix of constraints are computed analytically for LS-SVR. In contrast, the method of stochastic simplex approximated gradient (StoSAG) is employed for optimization with E2CO and HFS. The reservoir model considered in this study is a two-phase, three-dimensional reservoir characterized by channelized and heterogeneous permeability, sourced from the SPE10 benchmark case. We optimize well controls to maximize NPV in an oil-water waterflooding scenario. All proxy models can achieve optimal NPV results like those obtained through HFS but with significantly lower computational resources. Both proxy models are found to be approximately 15-fold more efficient than using HFS when the number of simulation runs is compared. Forward prediction results show that both proxy models outperform numerical simulator, and the E2CO can predict up to 2400 times faster than HFS whereas speedups gained over HFS go up to 5000-fold with LS-SVR. The training time required for E2CO is at least an order of magnitude longer than that for LS-SVR. The main contributions of the paper are (i) development of a novel methodology that uses an E2CO proxy model within a gradient-based iterative retraining proxy approach for life-cycle production optimization with nonlinear state constraints, (ii) comparison of this methodology in terms of computational cost and accuracy with an LS-SVR proxy model, and (iii) new insights into the accuracy and prediction performances of these machine learning-based proxy models for 3D oil-water systems as well as their efficiency in nonlinearly constrained production optimization for waterflooding applications.

Analytical calculation method for development dynamics of water-flooding reservoir considering rock and fluid compressibility

The existing development dynamics calculation methods for water-flooding reservoir are difficult to comprehensively consider factors such as injection-production imbalance, irregular well pattern, reservoir heterogeneity and compressibility. Therefore, leveraging reservoir engineering and material balance theory, and considering the influence of reservoir compressibility on reservoir development dynamics, a set of analytical calculation method for development dynamics of water-flooding reservoir considering rock and fluid compressibility water-flooding with clear theories and high computational efficiency were derived and constructed. Based on the oil-water two-phase Darcy law, the reservoir compression coefficient is introduced, and the development dynamics calculation method of a single injection-production unit considering compressibility is derived and established by combining the material balance theory, which can quantitatively describe the relationship between the oil and water production rates per unit. On this basis, the injection-production splitting strategy is introduced, which is extended to the calculation of development dynamics for multiple well groups in the whole reservoir. In this study, seven working conditions with various injection-production ratios were designed to validate the reliability of the new method. Subsequently, the method was applied to actual block for further verification, and the prediction accuracies of oil and water production rates were improved by 67.48% and 19.07%, respectively.