Water Production Rate Research Articles

Pilot Study on the Deep Treatment of Sulfuric-Acid–Titanium-Dioxide Wastewater Using an Ultrafiltration/Reverse Osmosis Process

The production of titanium dioxide via the sulfuric acid process generates large amounts of acidic wastewater. Investigating the possibility of reusing this wastewater after deep treatment can reduce pollutant discharge and conserve water resources. In a pilot study, a dual-membrane method of ultrafiltration (UF) and reverse osmosis (RO) was employed to perform deep treatments of sulfuric-acid–titanium-dioxide wastewater. The findings showed that the multimedia and precision filters reduced the turbidity of water from an external drainage to as low as 0.18 NTU, with a turbidity removal rate of approximately 50%, reaching a maximum of 68%. When the UF effluent had a membrane flux of 70–100 L/m2 h and a water production rate of 85–90%, the SDI15 was <5.0 and the turbidity was <1.0, meeting RO water supply requirements. Additionally, RO achieved a TDS removal rate of >95%, a CODCr removal rate of 85%, and a desalination rate of >98.5%. At a smooth operation system water recovery rate of 50%, the highest system recovery rate obtained was 64%. The water produced via RO adhered to reuse water standards. UF/RO deep treatment of sulfuric-acid–titanium-dioxide production wastewater and its reuse can realize comprehensive wastewater use and conserve water resources.

Design and optimization of an integrated novel desalination system based on the temperature difference between the sea and mountain

As the world’s population and increasing urbanization continue to grow, freshwater needs have risen dramatically. A desalination process based on a natural vacuum and pipeline desalination method that can produce freshwater and transfer it simultaneously is designed and modeled comprehensively in this research. It has been demonstrated that the effect of compressibility is negligible for pressure and temperature ranges of the system, indicating that the first system model using incompressible flow assumption is valid. Solar thermal energy was also utilized to improve the system’s efficiency. The results are investigated for three scenarios for Bandar-Abbas and the adjacent mountain, Genu. The first, second, and third scenarios are associated with the initial model based on pipeline desalination, the model utilizing solar cooling to reduce the temperature in the condensation section, and the model using solar energy to increase the temperature in the evaporation section, respectively. The results show that the highest freshwater production is estimated at 125,842,962 and 21,101,132 kg per year for a tube diameter of 2 and 1 m, respectively. Furthermore, the annual production rate of distilled water in scenarios #2 and #3 increased by 13.85% and 139.1% compared to scenario #1, with a tube diameter of 2 m.

Ice, Ice, Maybe? Investigating 46P/Wirtanen’s Inner Coma for Icy Grains

The release of volatiles from comets is usually from direct sublimation of ices on the nucleus, but for very or hyperactive comets other sources have to be considered to account for the total production rates. In this work, we present new near-IR (NIR) imaging and spectroscopic observations of 46P/Wirtanen taken during its close approach to Earth on 2018 December 19 with the MMIRS instrument at the MMT Observatory to search for signatures of icy or ice-rich grains in its inner coma that might explain its previously reported excess water production. The morphology of the images does not suggest any change in grain properties within the field of view, and the NIR spectra do not show the characteristic absorption features of water ice. Using a new Markov Chain Monte Carlo–based implementation of the spectral modeling approach of Protopapa et al., we estimate the areal water ice fraction of the coma to be <0.6%. When combined with slit-corrected Af ρ values for the J, H, and K bands and previously measured dust velocities for this comet, we estimate an icy grain production rate of less than 4.6 kg s−1. This places a strict constraint on the water production rate from pure icy grains in the coma, and in turn we find that for the 2018–2019 apparition approximately 64% of 46P’s surface was actively sublimating water near perihelion. We then discuss 46P’s modern properties within the context of other (formerly) hyperactive comets to understand how these complex objects evolve.

Enhancement of gas production from hydrate reservoir using a novel deployment of multilateral horizontal well

Most marine hydrates deposit in low permeable argillaceous sediments. However, the gas production rate of current field trials for hydrate reservoir is lower than the commercial criterion. To enhance gas production, a novel multilateral horizontal well was numerically investigated based on an unconfined hydrate reservoir in the Shenhu Area in the South China Sea. The investigation shows the novel deployment enhances gas production rate due to the enlarged dissociation region and a great quantity of stimulated hydrates. The release rate of gas from hydrate exceeds the production rate, 70% of produced gas is gaseous methane and water-to-gas ratio is favorable. For various factors, increasing the length and the number of lateral well significantly enhances the gas and water production rates, which raises about 30% with additional 100 m lateral well. The lateral well deployed in the middle of reservoir causes a high gas rate and low water rate, and the angle of the main and lateral wellbores (ANGMW&LW) slightly affects the gas production. The sequence of factor of the deployment on gas production herein is: well length, depth, spacing, ANGMW&LW. The commercial gas rate could be achieved with 22 groups of 1000 m length multilateral well.

Performance enhancement and parametric optimization of a sky radiative and thermoelectric hybrid cooling system for water harvesting from humid air

The aim of this study is to deepen into the study and analysis of energetic performance of a novel RSC-TEC hybrid cooling system for water harvesting by combining thermoelectric and radiative sky cooling mechanisms. The main contents of this study are to propose the thermodynamic model of the novel hybrid system considering main losses and steady-state assumption, solve the operating temperatures of the thermoelectric cooler by energy balance equations, discuss the influences of multiple system variables including air flow rate, electric current of the thermoelectric cooler, ambient relative humidity, and ambient temperature on effectiveness and water production rate, and, evaluate and compare the performances of the whole system and the thermoelectric cooler. The main novelties are to provide the parametric optimum selection criteria of some key parameters of the overall system operating at optimum states. Results show that the maximum effectiveness and water production rate of the hybrid system can reach 1.93×10- 6 kg J−1 (amount to 6.95×103 ml of water by consuming 1 kWh of electrical energy) and 1.51×10- 5 kg s−1 (amount to 54.4 ml of water within 1 h) at 0.75 relative humidity and the ambient temperature of 298 K. In addition, the system is capable of producing about 140 ml of water within 1 h from the air with high relative humidity, which is more efficient than other different existing air water generators. The optimized effectiveness (coefficient of performance) of the hybrid system is much better than that of a separate (subsystem) thermoelectric cooler operating at the same ambient condition. The results obtained reveal the advantages of the present hybrid system. Complementary perspectives on compromise performance regimes are also displayed from Pareto front yielded from numerical multi-parametric and multi-objective methods.

An effective PEMFC system shutdown purge strategy for improving the purging effect of liquid water and the dehydration of stack

The shutdown process is one of the critical stages when the proton exchange membrane fuel cell system runs as an actual application. Finding the effect of system operating conditions on shutdown purging could improve the purging effect of liquid water and the dehydration of the stack. In this study, an automotive fuel cell system of 350 single cells was developed on the vehicle scale and tested for factors that influence shutdown process. Seven shutdown purge cases for about 150 s were studied to investigate the shutdown purge strategy. It was found that 100% bypass valve opening reduced the purge time and improved the purge efficiency. The HCP speed should not be too slow or too fast in the shutdown process. The higher temperature of coolant water favored rapid shutdown and purge, and a large stoichiometric ratio of the cathode inlet improved the purge effect but enhanced the energy consumption of the air compressor. Neither too high nor too low purge pressure could blow out the liquid water more efficiently and improve the ohmic resistance. During purging, current density mainly influenced the water production rate and the maintenance state of stack temperature. With a higher stack temperature, purge process with a small current density could quickly reduce the stack humidity and enhance the ohmic resistance. Accelerating the opening rate of the anode purge valve could not effectively accelerate purge effect of the stack, while extending the valve closing time could improve hydrogen utilization. Future studies to investigate the combined impact of these factors on the fuel cell system shutdown purge will be carried out to develop the most effective strategy.

Performance analysis of nuclear powered desalination unit based on MED-TVC: a case study for Saudi Arabia

Abstract Nuclear desalination has been identified as an alternative option with much lower carbon dioxide emissions to provide fresh water by driving high capacity desalination plants. This work considers a theoretical analysis of using nuclear desalination to provide fresh water in three selected Saudi Arabian cities. It presents a theoretical model that integrates the characteristics of nuclear reactor, power cycle and desalination blocks. The power block includes three steam turbines and five feed water heaters. It is coupled via low pressure turbine to a multiple effect desalination unit integrated with a thermal vapor compressor encompassing eight effects, seven feed preheaters and a down condenser. The output includes work generated as function of fuel mass and reactor type, enrichment percentage, power and water production with different nuclear reactor type. Desalination performance indicators such as the fresh water production rate, gain output ratio (GOR), specific energy consumption (SEC) and specific cooling water mass flow rate have been evaluated and analyzed as function of sea water temperature for three specific Saudi cities. It was found that these indicators reflect better performance along a year for Jizan city than for Jubail and Tabuk. The case of Jizan city gives over the whole year more uniform values of water production rates, gain output ratio, specific energy consumption and cooling water mass flow rates.

A Lotus‐Petiole‐Inspired Hierarchical Design with Hydrophilic/Hydrophobic Management for Enhanced Solar Water Purification

AbstractSolar‐driven vapor generation offers an affordable and sustainable approach to solve global freshwater scarcity. Creating interfacial solar evaporators capable of increasing water production rates matching human water requirements is highly desirable but challenging due to the slow water transportation dynamics and unavoidable oil‐fouling. Herein, a bio‐inspired lotus‐petiole‐mimetic microstructured graphene/poly(N‐acryloyl glycinamide) solar evaporator with integrated hydrophilic and hydrophobic microregions is developed. Through accurate control of the supramolecular interactions, the optimized solar evaporator incorporating unique structural features and wettability shows high light harvesting, enhanced water activation, and reduced energy demand for water vaporization, enabling a groundbreaking comprehensive performance along evaporation rate up to 3.4 kg m−2 h−1 and energy conversion efficiency of ≈93% under one sun irradiation (1 kW m−2). Molecular dynamics simulations reveal that the abundant hydrogen bonding sites of the polymeric networks can thermodynamically modulate the escape behavior of water molecules. Notably, neither decrease in evaporation rate nor fouling on solar evaporators is observed during the prolonged purification process toward nano/submicrometer emulsions, oily brines, actual seawater, and domestic wastewater. This study provides distinctive insights into water evaporation behaviors at a molecular level and pioneers a rational strategy to design high‐yield freshwater‐generation systems for wastewater containing complex contaminants.

Experimental and numerical performance assessment of a hybrid parabolic dish collector with photovoltaic for a distiller

ABSTRACT Environmental pollution has been rising recently, and so clean water needing has also increased. People could have easy access to pure water in all environments and conditions. This study is the solar tracking parabolic dish collector with produced pure water independent of electricity (off-grid). This system is fully renewable and autonomous. This system possesses a receiver, a boiler, a condenser, six 1000 mm diameter parabolic dish collectors, and 1 kW photovoltaic (PV) collectors. Thermal oil uses as the working fluid in the experiments. The experiment measured solar radiation, air temperature, air velocity, oil inlet and outlet temperatures, oil flow rate, receiver side surface temperatures, and instantaneous amount of pure water. Numerical and thermal analysis of the receiver in the experimental setup carry out. ANSYS Fluent 18.1 uses for numerical analysis. Energy and exergy analysis calculates the receiver for pure water production rate. The time interval when the system operates at high performance determines. In this study investigates the behavior of some exergetic indicators on the performance of the experimental setup, the cost of the experimental setup, and the enviro-economic impact of the parabolic dish-type collector. For this purpose, some exergetic factors such as the exergy effect, environmental impact factor, waste exergy rate, improvement potential, and exergetic sustainability index examine. The receiver’s improvement potential is between 1700 and 3000 W. In addition, the sustainability index, waste exergy rate, and environmental impact factor range from 0.32 to 0.36, 0.90 to 0.94, and 2.6 to 3.0, respectively.

Solar steam-driven membrane filtration for high flux water purification

In recent years, interfacial solar steam generation has shown great potential for desalination with high solar-to-steam conversion efficiency. However, the freshwater production rate is still limited by the substantial latent heat of water evaporation and condensation efficiency. Here we designed an interfacial solar steam-driven reverse osmosis/nanofiltration device that generates high pressure that pushes water molecules through a filtration membrane to achieve separation from ions. The solar steam-driven reverse osmosis device reaches a water production rate as high as 81 kg m−2 h−1 under 12 sun illumination. Moreover, a theoretical model indicates that there still exists attractive room to further improve the freshwater output by optimizing the thermal insulation and expansion ratio of the device. This work paves a new way to design highly efficient miniaturized or decentralized drinking water devices. Reverse osmosis of seawater is a popular though energy demanding process to produce freshwater. Interfacing reverse osmosis membranes with solar steam generation shows potential for a more efficient desalination process.

History Matching of Reservoir Simulation Model: a Case Study from the Mishrif Reservoir, Buzurgan Oilfield, Iraq

In petroleum reservoir engineering, history matching refers to the calibration process in which a reservoir simulation model is validated through matching simulation outputs with the measurement of observed data. A traditional history matching technique is performed manually by engineering in which the most uncertain observed parameters are changed until a satisfactory match is obtained between the generated model and historical information. This study focuses on step by step and trial and error history matching of the Mishrif reservoir to constrain the appropriate simulated model. Up to 1 January 2021, Buzurgan Oilfield, which has eighty-five producers and sixteen injectors and has been under production for 45 years when it started in 1976. Reservoir exhibits heterogeneity in porosity and permeability throughout the field, therefore it’s a big challenge to control all reservoir properties during matching process. The historical matching process includes matching field and wells oil and water production rates, water injection rates, water cut, and reservoir static pressure. Finally, the results show that the good matching between simulated model and observed data; oil and water production rates, water injection rates, water cut, and static reservoir pressure which allow for implementing perfect future production forecasting strategies.

A Fully Coupled Thermo-Hydro-Mechanical-Chemical Model for Methane Hydrate Bearing Sediments Considering the Effect of Ice

The ice generation is one of the challenges facing the methane hydrate depressurization, which, however, has not been fully addressed by existing numerical models for hydrate-bearing sediments (HBS). In this study, we develop a high-fidelity, fully coupled thermo-hydro-mechanical-chemical numerical model that incorporates the effect of ice. The model, developed using COMSOL, takes into account water–ice phase change, thermally induced cryogenic suction and constitutive relation in HBS. It is verified well against the temperature, pressure and cumulative gas production of Masuda’s experiment. The model is then employed to investigate multiphysical responses and gas/water production when ice generation is induced by setting a low outlet pressure. The results reveal that ice forms near the outlet boundary of the specimen center, leading to a reduction in intrinsic permeability and fluid velocity and an increase in the bulk modulus of ice-HBS. This enhanced bulk modulus results in higher porosity under axial load. Although the exothermic effect of ice generation promotes the hydrate dissociation, the effect on cumulative gas production is negligible after the ice melts. A negative correlation between ice saturation and water production rate is observed, indicating that a higher gas–water ratio can be achieved by adjusting the ice duration during hydrate production. The developed coupled model proves to be crucial for understanding the effect of ice on hydrate exploitation.

Performance assessment of hemispherical solar distillers integrated with the red bricks filled with cement as natural thermal storage materials

AbstractThis manuscript aims to augment the production rate of drink water from the hemispherical solar distillers using red bricks filled with cement as natural low‐cost reasonable storage materials. To obtain the optimal height and optimal gap distance of the red brick tiles filled with cement that achieves the highest productivity of hemispherical distillers. Three different heights of the red brick (1, 2, and 3 cm) with two different gap distances of (4 and 6 cm) were experimentally studied. Therefore, three hemispherical distillers were constructed and operated under the same climate conditions. The first is the traditional hemispherical solar distiller (THSD) which represents the reference distiller. The second is a hemispherical distiller with red brick tiles filled with cement set at a gap distance of 6 cm. The third is a hemispherical distiller with red brick tiles filled with cement set at a gap distance of 4 cm. The results presented that, the utilization of red brick tiles filled with cement with a height of 2 cm and a gap distance of 4 cm represents a good choice that achieves the highest performance of hemispherical distillers. The results showed that the utilization of red bricks filled with cement will be improved the accumulative yield from 4.3 L/m2/day (THSD) to 6.55 L/m2/day with an improvement of 52.3%. Also, using the red bricks filled with cement improved the thermal and exergy efficiencies by 51.24% and 435.5%, respectively compared to THSD.

Water production rates from SOHO/SWAN observations of comets C/2020 S3 (Erasmus), C/2021 A1 (Leonard) and C/2021 O3 (PanSTARRS)

In 2021 and 2022 the hydrogen comae of three long period comets, C/2020 S3 (Erasmus), C/2021 A1 (Leonard) and C/2021 O3 (PanSTARRS) were observed with the Solar Wind ANisotropies (SWAN) all-sky hydrogen Lyman-alpha camera on the SOlar and Heliosphere Observer (SOHO) satellite. SWAN obtains nearly daily full-sky images of the hydrogen Lyman-α distribution of the interstellar hydrogen as it passes through the solar system yielding information about the solar wind and solar ultraviolet fluxes that eats away at it by ionization and charge exchange. The hydrogen comae of comets, when of sufficient brightness, are also observed. Water production rates have been calculated over time for each of these comets. Of particular interest are comet C/2021 O3 (PanSTARRS) which apparently disintegrated a few days before its perihelion at 0.28 au and C/2021 A1 (Leonard) which also disintegrated beginning about 20 days after its perihelion peak. The behavior of comet C/2020 S3 (Erasmus) was more typical without dramatic fading, but still was asymmetric about perihelion, with a more rapid turn on before perihelion and more extended activity well after perihelion.

Unraveling the Influence of Water and Nitrogen Management on Quinoa (Chenopodium quinoa Willd.) Agronomic and Yield Traits

Effective management is crucial to achieve the high yield potential of quinoa (Chenopodium quinoa Willd.), renowned for its resilience in harsh environments, to meet the rising global demand. The present study examines how varying levels of water and nitrogen affect the agronomic and yield traits of quinoa (cv. Q-36) during the two growing seasons of 2020/2021 and 2021/2022. The experiment was a 3 × 4 factorial laid out in a randomized complete block design with three replications per treatment during the two seasons of the study, as water regimes were considered the main factor, including 100%, 80%, and 60% ETc, whereas nitrogen levels were considered the sub-plot factor, comprising four levels (75, 150, 225, and 300 kgN ha−1). The analysis of variance indicated that nitrogen level, irrigation regime, and irrigation regime × nitrogen level had highly significant effects (p &lt; 0.001) on all studied traits, including plant height, panicle length, dry weight, seed weight, seed yield, and total yield in the two growing seasons under study. For all traits of study, the combined application of 100% ETc with 300 kgN, followed by 80% ETc with 225 kgN, resulted in the highest value of plant height, panicle length, dry weight, seed weight, seed yield, and total yield, whereas the combination of 60% ETc and 75 kgN applications resulted in the lowest value for all of the aforementioned traits. Furthermore, the water regime impacted water productivity at all nitrogen levels as the highest productivity level was recorded under the 80% ETc (0.58 kg/m3), followed by the 100% ETc (0.54 kg/m3), and the 60% ETc (0.52 kg/m3). The highest water productivity rate was observed at 300 kg/ha of the nitrogen levels for 60% and 80% ETc regimes, where water productivity levels were 0.73 and 0.71 (kg/m3), respectively. The results also indicate that the water productivity of quinoa plants is noticeably affected by both water regime and nitrogen level; as the water regimes decrease from 100% to 60% ETc, water productivity increases for all nitrogen levels. The information obtained from these results can be applied to optimize the methods for cultivating quinoa under conditions of water scarcity and minimal nitrogen availability, thus gaining an insight into the impact of these conditions on quinoa growth and yield.

Optimizing the Maize Irrigation Strategy and Yield Prediction under Future Climate Scenarios in the Yellow River Delta

The contradiction between water demand and water supply in the Yellow River Delta restricts the corn yield in the region. It is of great significance to formulate reasonable irrigation strategies to alleviate regional water use and improve corn yield. Based on typical hydrological years (wet year, normal year, and dry year), this study used the coupling model of AquaCrop, the multi-objective genetic algorithm (NSGA-III), and TOPSIS-Entropy established using the Python language to solve the problem, with the objectives of achieving the minimum irrigation water (IW), maximum yield (Y), maximum irrigation water production rate (IWP), and maximum water use efficiency (WUE). TOPSIS-Entropy was then used to make decisions on the Pareto fronts, seeking the best irrigation decision under the multiple objectives. The results show the following: (1) The AquaCrop-OSPy model accurately simulated the maize growth process in the experimental area. The R2 values for canopy coverage (CC) in 2019, 2020, and 2021 were 0.87, 0.90, and 0.92, respectively, and the R2 values for the aboveground biomass (BIO) were 0.97, 0.96, and 0.96. (2) Compared with other irrigation treatments, the rainfall in the test area can meet the water demand of the maize growth period in wet years, and net irrigation can significantly reduce IW and increase Y, IWP, and WUE in normal and dry years. (3) Using LARS-WG (a widely employed stochastic weather generator in agricultural climate impact assessment) to generate future climate scenarios externally resulted in a higher CO2 concentration with increased production and slightly reduced IW demand. (4) Optimizing irrigation strategies is important for allowing decision makers to promote the sustainable utilization of water resources in the study region and increase maize crop yields.

Functional anode of membrane capacitive deionization enabled by Cu2+/Cu+ redox couple for simultaneous anions removal and anodic oxidation mitigation

Activated carbon (AC) based conventional capacitive deionization has shown extraordinary promise for energy efficient water treatment, but its capacity and cycle stability are limited by the mechanism of electric double-layer and the oxidation of anode, respectively. Redox electrolytes are proposed as one of the most promising strategies to improve the charge storage capacitance. Here, functional anode enabled by Cu2+/Cu+ redox couple is constructed by adding 10 mM CuCl2 into 100 mM NaCl supporting electrolyte. A membrane capacitive deionization (MCDI) cell with the functional anode and anion exchange membrane, employing a two channel structure is proposed to remove the anions (F−, Cl−) from wastewater. The reverse constant current discharge mode with 1.2 V/−1.2 V cut-off voltage can realize Cu2+/Cu+ redox reaction. The water production rate of the MCDI cell is above 50 % and the Cl− removal capacity is increased by 163 % due to the additional faradaic process. The cell capacity can be maintained above 83 % after 40 cycles. In particular, fast charge balance and redox couple reaction processes of this functional anode could significantly alleviate the oxidation of the anode AC electrode. This work provides new opportunities for developing cost-effective technologies to remove the anions from wastewater.

Evaporation-Assisted Humidification–Dehumidification Cycles for Desalination Application in Tropical and Subtropical Regions

The present study aims to evaluate the performance of evaporation-assisted humidification–dehumidification (E-HDH) desalination, specifically direct evaporative (DE-HDH), indirect evaporative (IE-HDH), and Maisotsenko evaporative (ME-HDH) systems. To achieve this, a thermodynamic modeling approach is utilized, which incorporates the wet bulb effectiveness method, psychrometric relationships of humid air, and equations that govern heat and mass balance. The key performance indicators of the studied E-HDH desalination systems are estimated concerning operating parameters. The results show that the ME-HDH system is capable of producing a comparatively higher water production rate (WPR) ranging between 0.01 and 7.92 g/s as compared to the DE-HDH and IE-HDH systems. The sensible cooling flux was observed to be high at a dry-bulb temperature (Tdb) of 50 °C and relative humidity (RH) &lt; 0.2, having a value of 5.26 kW for the DE-HDH system, followed by the ME-HDH system (3.23 kW) and the IE-HDH system (3.11 kW) due to relatively high mass flow rates. The latent heat flux was observed to be relatively high in the case of the ME-HDH system. Minimum specific energy consumption was observed from the ME-HDH system, and consequently, a maximum gain output ratio (3.32) was realized. In addition, the study realized that an increment in air velocity and wet bulb effectiveness significantly improves the WPR. In accordance with the climatic conditions of the studied Saudi Arabia cities, it has been realized that Al-Hofuf and Riyadh produce relatively high WPRs with minimum energy consumption. In the case of Al-Hofuf, the average WPR was recorded as 185.51 kg/day, followed by Riyadh (180.33 kg/day). The energy required was estimated to be 0.042 kWh/kg and 0.034 kWh/kg for both cities, accordingly.

Numerical Simulation of a Class I Gas Hydrate Reservoir Depressurized by a Fishbone Well

The results of the second trial production of the gas hydrate reservoir in the Shenhu area of the South China Sea show that the production of a gas hydrate reservoir by horizontal wells can greatly increase the daily gas production, but the current trial production is still far below the minimum production required for commercial development. Compared with a single horizontal well, a fishbone well has a larger reservoir contact area and is expected to achieve higher productivity in the depressurization development of gas hydrate reservoirs. However, there is still a lack of systematic research on the application of fishbone wells in Class I gas hydrate reservoirs. In this paper, a grid system for gas hydrate reservoirs containing fishbone wells is first established using the PEBI unstructured grid, and fine-grained simulation of reservoirs near the bottom of the wells is achieved by adaptive grid encryption while ensuring computational efficiency. On this basis, Tough + Hydrate software is adopted to simulate the productivity and physical field change of a fishbone well with different branching numbers. The results show that: the higher the number of branches in a fishbone well, the faster the free water production rate, reservoir depressurization, and free gas production rate in the initial stage of depressurization development, and the faster depressurization can effectively promote hydrate dissociation. Compared with a single horizontal well, the cumulative gas production of a six branch fishbone well can increase by 59.3%. Therefore, using multi-branch fishbone depressurization to develop Class I gas hydrate reservoirs can effectively improve productivity and the depressurization effect, but the hydrate dissociation will absorb a lot of heat and lead to a rapid decrease in reservoir temperature and hydrate dissociation rate. At the end of the simulation, the hydrate dissociation rate of all schemes was lower than 50%. In the later stage of depressurization development, the combined development method of heat injection and depressurization is expected to further provide sufficient thermal energy for hydrate dissociation and promote the dissociation of the hydrate.

Development and evaluation of a solar based integrated hydrogen energy system for mobile applications

Sustainable and nature-friendly energy systems are critical in playing a key role in meeting the needs for better energy security and reduced environmental impacts which appear among the primary concerns of today’s modern society in the 21st century. The present study, in this regard, undertakes the development and thermodynamic investigation of a unique solar energy-based multigenerational energy system for modular and transportable applications. Electricity, heat, hot water, hydrogen and clean water are the useful commodities generated by this uniquely integrated energy system. This system employs a photoelectrochemical reactor stack for wastewater treatment and hydrogen production. The hydrogen generated from the photoelectrochemical water splitting process is employed within a proton exchange membrane fuel cell providing electricity and heat for hot water. The system’s energetic and exergetic efficiencies under different operational conditions are investigated and comparatively evaluated. The key effects of varying prime operational conditions and state properties on the system performance and hence the efficiency, as considered in the system analysis, are parametrically investigated, and the obtained results are comprehensively discussed along with explanations about the main drivers. The integrated system provides 1.026 kW electrical power along with, 2.1 kW space heating, 0.6 kW heat for hot water, and hydrogen and clean water production rates of 22.97 mg/s and 9.79 g/s, respectively. An overall energy efficiency of 16.79 % and an overall exergy efficiency of 17.31 % are obtained and discussed. The presently developed system is capable of operating as a self-standing system in an off-grid manner. Furthermore, the number of PEC reactors required to sustain the system needs to be maintained, which can be achieved by potential improvement in PEC water splitting process.