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An accident in a nuclear power plant involving a reactor core meltdown could result in the instigation of molten corium, which is a mixture of nuclear fuel, claddings and structural components. In this paper, an enthalpy-porosity model is proposed to comprehensively analyze the ablation of concrete during the molten corium and concrete interaction process. The developed numerical model is an extension of the enthalpy-porosity model and is termed the CCEPM. The developed CCEPM computational fluid dynamics model can predict natural convection, melting and solidification. The developed model simplifies the complex phenomena of concrete ablation and melting by incorporating the multiregional approach. The model was implemented in OpenFOAM by developing a new solver that couples buoyant-driven natural convection and conjugate heat transfer solvers. The thermal modeling and heat transfer capabilities of the developed solver were verified against experimental data sets. Additionally, the effects of various boundary conditions, concrete thermal conductivities and decay heat intensities were analyzed to study their impacts on concrete ablation. We observed significant low concrete ablation and controlled temperature and velocity fields for the water-cooled boundary condition. Accordingly, the ablation of concrete decreased by 17% by imposing the water-cooled boundary condition. Similarly, when the thermal conductivity of concrete was decreased to 0.43 and 0.13 W/m.K, the ablation of the concrete decreased by 38% and 75%, respectively. Furthermore, early cooling of molten corium to decrease the decay heat was found to be an effective strategy for successfully mitigating concrete ablation by 20%. [ABSTRACT FROM AUTHOR]

Polymer injection into oil reservoirs stands as a primary technique for enhanced oil recovery (EOR), employing either natural or synthetic polymers that dissolve in water. Proper performance in salinity and reservoir temperature creates a limitation to replace natural material with common chemicals and this has led researchers to try to identify new material for this application. Continuing the efforts and overcoming the challenge, this research introduces and examines a high‐performance natural polymer extracted from garden cress seeds for this application. Several experiments were planned and executed based on the existing EOR standards and literature. Comprehensive analyses and viscosity measurements were performed to identify the behaviour of solutions and the effects of concentration, shear rate, salinity, and temperature. Essential tests such as wettability and polymer adsorption were also done by contact angle measurement and flooding into a sandstone plug, respectively. The produced polymer was able to effectively maintain the viscosification properties at temperatures up to 95°C. Similarly, increasing the salinity up to 140,000 ppm did not affect its efficiency and the viscosity value remained in the useful range. The viscosity of the mature solutions at 35°C after 30 h at concentrations of 200, 400, 600, 800, 1000, and 1200 ppm was 8.61, 18.59, 31.27, 65.41, 95.38, and 149.75 mPa, respectively. At 1000 ppm and temperatures of 35, 55, 75, and 95°C, the viscosity was 95.38, 90.57, 86.73, and 84.72 mPa · s, respectively. At concentrations of 600, 800, and 1000 ppm, the wettability altered to intermediate‐wet, while at 1200 ppm, altered to water‐wet. Polymer injection caused an increase in recovery equal to 18.6%. The water cut increased with a little delay in the initial volumes of water injection at a high rate and reached its maximum. Then after the injection of 0.3 PV of polymer, there was a sharp and continuous drop until reaching 35% of the production fluid volume. [ABSTRACT FROM AUTHOR]

Decision-making is among the main concerns in management discussions. This applied research is about a Multiple Criteria Decision Making problem since the decision-making process is drawn upon quantitative and qualitative criteria under uncertain conditions. This study was conducted for an oil reservoir consisting of nine criteria and eight alternatives. To form the network structure and recognize the relationships between the criteria, alternatives, and criteria weights, the Fuzzy Analytic Network Process (FANP) was used. Moreover, the Interval Valued Intuitionistic Fuzzy-TODIM (IVIF-TODIM) technique prioritized the alternatives. A case study was applied to demonstrate and show the suitability of the suggested method. The study's objective is to prioritize enhanced oil recovery (EOR) methods based on the feasibility criteria using the FANP and IVIF-TODIM techniques. This issue is required to implement the research because not all the EOR methods are implemented practically. They should be prioritized and chosen based on the budget, available infrastructures, and other important factors. The important issue is the manager's decision to choose the best method by considering different indicators. This method is a tool for better decision-making. Using these techniques, low salinity water injection was selected as the best and most effective and feasible method. [ABSTRACT FROM AUTHOR]

The phenomenon of pore blockage caused by injected suspended particles significantly impacts the efficiency of water injection and production capacity release in offshore oilfields, leading to increased additional resistance during the injection process. To enhance water injection volumes in injection wells, it is essential to quantitatively study the additional resistance caused by suspended particle blockage during water injection. However, there is currently no model for calculating the additional resistance resulting from suspended particle blockage. Therefore, this study establishes a permeability decline model based on the microscopic dispersion kinetic equation of particle transport. The degree of blockage is characterized by the reduction in fluid volume, and the additional resistance caused by particle migration and blockage during water injection is quantified based on the fluid volume decline. This study reveals that over time, suspended particles do not continuously migrate deeper into the formation but tend to deposit near the wellbore, blocking pores and increasing additional resistance. Over time, the concentration of suspended particles near the wellbore approaches the initial concentration of the injected water. An increase in seepage velocity raises the peak concentration of suspended particles, but when the seepage velocity reaches a certain threshold, its effect on particle migration stabilizes. The blockage location of suspended particles near the wellbore is significantly influenced by seepage velocity and time. An increase in particle concentration and size accelerates blockage formation but does not change the blockage location. As injection time increases, the fitted injection volume and permeability exhibit a power-law decline. Based on the trend of injection volume reduction, the additional resistance caused by water injection is calculated to range between 0 and 3.85 MPa. Engineering cases indicate that blockages are challenging to remove after acidification, and the reduction in additional resistance is limited. This study provides a quantitative basis for understanding blockage patterns during water injection, helps predict changes in additional resistance, and offers a theoretical foundation for targeted treatment measures. [ABSTRACT FROM AUTHOR]

This study focuses on the design and validation of a computer program named "SPsim", developed using Visual Basic coding and advanced Excel tools to predict the formation of sulfate mineral deposits during water injection in oil fields. Water injection for secondary oil recovery is an effective economic strategy, but it can be negatively impacted by the formation of sulfate minerals such as calcium sulfate, gypsum, barium sulfate, and strontium sulfate. The results of this study demonstrate that SPsim can accurately predict the formation of these mineral deposits based on the composition of the formation water and injection water under various temperature and pressure conditions. Specifically, the formation of barium sulfate and calcium sulfate is observed under certain conditions, which is a significant concern in oil fields. The study also highlights that calcium sulfate, barium sulfate, and strontium sulfate are among the most challenging mineral deposits in the studied fields, while the formation of gypsum deposits is less significant. The program was compared with results from other software tools, such as ScaleChem 3.2 and StimCad 2, as well as field observations. The findings indicate that SPsim provides a reliable and effective tool for predicting and managing sulfate scaling in water injection operations, making it a valuable resource for both industrial and academic applications. [ABSTRACT FROM AUTHOR]

Water in the engine/combustion chamber is not a novel phenomenon. Even humidity has a major effect on internal combustion engine emissions and can thus be considered the first invisibly present emission technology. With modern techniques, the problematic aspects of water, such as corrosion and lubrication issues, seem to disappear, and the benefits of water's effect in combustion may also be enhanced in the context of EURO 7. The current study examines the literature on the effects of water on diesel combustion in chronological sequence, focusing on changes over the last three decades. Then it analyzes and re-evaluates the water effect in the current technology and the forthcoming Euro 7 regulatory context, comparing the conclusions with current automotive applications and mobility trends, in order to show the possible benefits and prospective research avenues in this sector. Techniques introducing water to combustion could be a major approach in terms of the EURO 7 retrofit mandate, as well as a feasible technique for concurrent nitrogen oxides and particulate reduction. [ABSTRACT FROM AUTHOR]

Offshore oil field loose sandstone reservoirs have high permeability. However, during the water injection process, water injection blockage occurs, causing an increase in injection pressure, making it impossible to continue injecting water on site. Current research mainly focuses on the factors causing water injection blockage, with less attention given to the blockage locations and the pressure increase caused by water injection. There is a lack of research on the change in the law of injection capacity. This paper establishes a simulation experiment for water injection blockage that can accommodate both homogeneous and heterogeneous cores. The experimental core is 1 m long and capable of simulating the blockage conditions in the near-well zone during water injection, thereby analyzing the core blockage position and blockage pressure. The study clarifies the influence of water quality indicators, heterogeneity, and core length on the blockage patterns in reservoirs during water injection. The research findings are as follows: I. The reservoir blockage samples were characterized using scanning electron microscopy (SEM), casting thin sections, and X-ray diffraction (XRD) analysis. The results indicate that the main factors causing blockage are clay, silt, and fine particulate suspensions, with the fine particles mainly consisting of hydrated silicates and alkali metal oxides. The primary cause of blockage in loose sandstone is identified as the mechanism of migration and accumulation of clay, fine rock particles, and suspended matter in the injected water. II. By monitoring pressure and permeability changes in the core flooding experiments, the impact of reservoir heterogeneity on water injection capacity was evaluated. The evaluation results show that the blockage locations and lengths in heterogeneous cores are twice those in homogeneous cores. III. For heterogeneous reservoirs, if the initial permeability at the inlet is lower than in other segments of the core, significant blockage resistance occurs, with the final resistance being 1.27 times that of homogeneous cores. If the initial permeability at the inlet is higher than in other parts, the final blockage resistance is close to that of homogeneous cores. This study provides theoretical support for the analysis of blockage locations and pressures in loose sandstone water injection and offers technical support for the design of unplugging ranges and pressures after blockage in heterogeneous formations. At the same time, it provides a theoretical basis for selecting the direction of acidizing after blockage occurs in loose sandstone. [ABSTRACT FROM AUTHOR]

Stress sensitivity and dynamic relative permeability are undeniable phenomenon in oil reservoir numerical simulation. In this paper, a complex two-phase flow model was established considering the deformation of porous media and relative permeability dynamic changes during water injection. A sensitivity analysis on this new model is carried out. The results reveal that stress sensitivity is a key factor that cannot be ignored when using reservoir numerical simulation to calculate water saturation. When the stress-sensitivity coefficient is not considered, the average water saturation of the model is 51.59%. When the stress-sensitivity coefficient is 0.12MPa−1, the average water saturation of the model is 48.45%. After considering stress sensitivity, the average water saturation of the model decreases by 6.1%. The water saturation difference between the new model and the traditional model is mainly reflected in the vicinity of the water injection well. Additionally, the influence of the range of changes in reservoir permeability on the calculation of water saturation by the new model cannot be ignored. [ABSTRACT FROM AUTHOR]

The main objective of this study is to develop spark ignition engine parameters that allow complete combustion while reducing dependence on fossil fuels. To achieve this goal, optimization of compression ratio, gasoline-ethanol mixture, ignition timing, and spark plug type was used. In addition, this study used water injection that continuously injects water before the intake manifold. In this study, the Taguchi method with the L9 orthogonal array was applied. According to the experimental verification results, the best combination to reduce exhaust emission levels is to utilize gasoline-ethanol (E70), a compression ratio (CR) of 15.6:1, an ignition degree of +4°, and a platinum spark plug. Meanwhile, the presence of water injection at 1.45 ml/s helps reduce vehicle exhaust pollutants. [ABSTRACT FROM AUTHOR]

At present, many offshore oil fields are facing problems, such as pollution-induced near-well zone blockage, poor inter-well connectivity, and strong vertical heterogeneity, which lead to insufficient formation energy and low production in the middle and late stages of development. It is necessary to develop a new technology to overcome these issues. In this regard, water-injection-induced dilation technology, which was already proven to have positive effects on loose sandstone reservoirs, was controversially applied to an offshore low-permeability reservoir. To investigate whether the water-injection-induced dilation technology is suitable, experiments were conducted to analyze the dilation potential of offshore low-permeability sandstone reservoirs, namely, X-ray diffraction, laser particle size analysis, physical simulation, computed tomography scan, and electron microscope scanning experiments. The X-ray diffraction experiments showed that the samples had more than 80% non-clay mineral content and a high brittleness index, which meant more complex microfractures under water injection. Particle size analysis experiments revealed that the particle size was mainly between 10 μm and 100 μm, and thus belonged to coarse silty sand. According to the sorting grade, the sample particle size distribution was uniform and the reservoir was more prone to dilation. The true triaxial physical simulation showed that a volumetric dilation zone occurred around the wellbore, where complicated microfractures occurred. This paper provides adequate evidence and mechanisms of dilation potential for an offshore low-permeability sandstone reservoir. [ABSTRACT FROM AUTHOR]

The use of high-pressure water injection technology in gas-bearing coal seams is an important method for effectively addressing coalbed methane issues. To explore the mechanisms and influencing factors of water injection and permeability enhancement, a model was established based on the theories of unstable seepage and elastic damage in coal and rock mass. Additionally, a mechanical model of elastic damage-based beams was established, taking into account rheological damage, and the mechanical property variation of the surrounding rock in the working face was analyzed. The study included numerical simulations and verification with practical examples. The results suggested that high-pressure water injection could cause damage to the coal body and deformation of the roof, resulting in changes in ground stress, which was a significant contributor to the increase in coal seam permeability. The study showed positive correlations between rheological effects, injection time, injection flow rate, coal seam depth, and the influence range of water injection. Case studies indicated that the long-term influence range of water injection was approximately 60 m, which aligned with field results. The paper introduces a mechanical model for calculating variations in ground stress. This model can help assess the impact of water injection and permeability enhancement, providing valuable insights for related engineering projects. [ABSTRACT FROM AUTHOR]

Water injection for oil displacement is one of the most effective ways to develop fractured-vuggy carbonate reservoirs. With the increase in the number of rounds of water injection, the development effect gradually fails. The emergence of high-pressure capacity expansion and water injection technology allows increased production from old wells. Although high-pressure capacity expansion and water injection technology has been implemented in practice for nearly 10 years in fractured-vuggy reservoirs, its mechanism remains unclear, and the water injection curve is not apparent. In the past, evaluating its effect could only be done by measuring the injection-production volume. In this study, we analyze the mechanism of high-pressure capacity expansion and water injection. We propose a fluid exchange index for high-pressure capacity expansion and water injection and establish a discrete model suitable for high-pressure capacity expansion and water injection curves in fractured-vuggy reservoirs. We propose the following mechanisms: replenishing energy, increasing energy, replacing energy, and releasing energy. The above mechanisms can be identified by the high-pressure capacity expansion and water injection curve of the well HA6X in the Halahatang Oilfield in the Tarim Basin. By solving the basic model, the relative errors of Reservoirs I and II are found to be 1.9% and 1.5%, respectively, and the application of field examples demonstrates that our proposed high-pressure capacity expansion and water injection indicator curve is reasonable and reliable. This research can provide theoretical support for high-pressure capacity expansion and water injection technology in fracture-vuggy carbonate reservoirs. [ABSTRACT FROM AUTHOR]

Water injection for absorbing corrosive gases NH3, HCl and H2S is a widely employed method to mitigate the risk of ammonium salt corrosion in the hydrogenation units. To ensure the efficient prevention of ammonium salt corrosion, a numerical model integrating the hydrodynamics of gas–liquid and the reaction of interphase mass transfer was built based on Euler–Lagrange method in this work. The flow and mass transfer characteristics of complex multi-component system in water injection pipeline were investigated, and the correlation between process operating conditions and gas removal performance was analyzed. The results reveal that the removal efficiencies of corrosive gases in pipeline are influenced by the characteristics of gas–liquid flow and mass transfer, with HCl showing higher removal efficiency compared to NH3 and H2S. Furthermore, the increasing flow rate of water injection, the reducing corrosive medium content and the decreasing droplet diameter have a positive impact on the removal efficiencies of corrosive gases, while the impact of gas-flow velocity on the removal efficiencies of corrosive gases primarily depends on the residence time of droplets. These results have important theoretical value and engineering guiding significance for intensifying the process of water injection in hydrogenation units. [ABSTRACT FROM AUTHOR]

Dynamic fracture propagation significantly affects water flooding efficiency in tight oil reservoirs. This phenomenon, where moderate fracture openings can enhance water flooding volume and alleviate injection challenges, has been underexplored in current literature. Understanding dynamic fracture behavior poses a challenge due to the difficulty in characterizing them within traditional reservoir numerical simulators. In this study, we propose a numerical simulation method that integrates the KGD dynamic fracture model with a two-phase flow model. This approach enables detailed exploration of dynamic fracture evolution in reservoir scenarios featuring one injector and one production well. Our findings reveal that fractures extend from the water injection well to the oil production well, exhibiting rapid initial growth followed by a slower rate. Fluctuations in fracture tip pressure correspond to cycles of opening and closure. We observe that cumulative oil production increases more rapidly when injection pressure exceeds the fracture opening pressure. However, this growth rate diminishes beyond a certain threshold, highlighting the critical role of injection parameters in dynamic fracture efficacy. Optimal water flooding performance is achieved when injecting water slightly above the fracture opening pressure. Furthermore, we compare water cut curves generated by conventional commercial simulators with our fracture propagation model. Our model's water cut curve aligns better with on-site data, indicating improved historical fitting accuracy. In conclusion, our study underscores the importance of dynamic fractures in enhancing water flooding efficiency in tight oil reservoirs and presents a robust numerical simulation framework for better understanding and management of reservoir dynamics. [ABSTRACT FROM AUTHOR]

This study investigates cloud cavitation suppression around a model-scale NACA66 hydrofoil using active water injection and explores the effect of multiple injection parameters. Numerical simulations and a mixed-level orthogonal test method are employed to systematically analyze the impact of jet angle αjet, jet location Ljet, and jet velocity Ujet on cavitation suppression efficiency and hydrofoil energy performance. The study reveals that jet location has the greatest influence on cavitation suppression, while jet angle has the greatest influence on hydrofoil energy performance. The optimal parameter combination (Ljet = 0.30C, αjet = +60 degrees, Ujet = 3.25 m/s) effectively balances energy performance and cavitation suppression, reducing cavitation volume by 49.34% and improving lift–drag ratio by 8.55%. The study found that the jet's introduction not only enhances vapor condensation and reduces the intensity of the vapor–liquid exchange process but also disrupts the internal structure of cavitation clouds and elevates pressure on the hydrofoil suction surface, thereby effectively suppressing cavitation. Further analysis shows that positive-going horizontal jet components enhance the lift–drag ratio, while negative-going components have a detrimental effect. Jet arrangements near the trailing edge negatively impact both cavitation suppression and energy performance. These findings provide a valuable reference for selecting optimal injection parameters to achieve a balance between cavitation suppression and energy performance in hydrodynamic systems. [ABSTRACT FROM AUTHOR]

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The energy release process of the Mg-based hydroreactive fuels directly affects the performance of water ramjet engines, and the burning rate is one of the key parameters of the Mg-based hydroreactive fuels. However, there is not enough in-depth understanding of the combustion process of Mg-based hydroreactive fuels within the chamber of water ramjet engines, and there is a lack of effective means of prediction of the burning rate. Therefore, this paper aims to examine the flame structure of Mg-based hydroreactive fuels with a high metal content and analyze the impact of the water injection velocity and droplet diameter on the combustion property. A combustion experiment system was designed to replicate the combustion of Mg-based hydroreactive fuels within water ramjet engines, and the average linear burning rate was calculated through the target line method. On the basis of the experiment, a combustion–flow coupling solution model of Mg-based hydroreactive fuels was formulated, including the reaction mechanism between Mg/H2O and the decomposition products from an oxidizer and binder. The model was validated through experimental results with Mg-based hydroreactive fuels at various pressures and water injection velocities. The mean absolute percentage error (MAPE) in the experimental results was less than 5%, proving the accuracy and validity of the model. The resulting model was employed for simulating the combustion of Mg-based hydroreactive fuels under different water injection parameters. The addition of water injection resulted in the creation of a new high-temperature region, namely the Mg/H2O non-premixed combustion region in addition to improving the radial diffusion of the flame. With the increasing water injection velocity, the characteristic distance of Mg/H2O non-premixed combustion region is decreased, which enhances the heat transfer to burning surface and accelerates the fuel combustion. The impact of droplet parameters was investigated, revealing that larger droplets enhance the penetration of the fuel-rich gas, which is similar to the effect of injection velocity. However, when the droplet size becomes too large, the aqueous droplets do not fully evaporate, resulting in a slight decrease in the burning rate. These findings enhance the understanding of the mechanisms behind the burning rate variation in Mg-based hydroreactive fuels and offer theoretical guidance for the optimal selection of the engine operating parameters. [ABSTRACT FROM AUTHOR]

The main objective of this study is to develop spark ignition engine parameters that allow complete combustion while reducing dependence on fossil fuels. To achieve this goal, optimization of compression ratio, gasoline-ethanol mixture, ignition timing, and spark plug type was used. In addition, this study used water injection that continuously injects water before the intake manifold. In this study, the Taguchi method with the L9 orthogonal array was applied. According to the experimental verification results, the best combination to reduce exhaust emission levels is to utilize gasoline-ethanol (E70), a compression ratio (CR) of 15.6:1, an ignition degree of +4°, and a platinum spark plug. Meanwhile, the presence of water injection at 1.45 ml/s helps reduce vehicle exhaust pollutants.

With the rapid progress of big data and artificial intelligence, machine learning technologies such as learning and adaptive control have emerged as a research focus in petroleum engineering. They have various applications in oilfield development, such as parameter prediction, optimization scheme deployment, and performance evaluation. This paper provides a comprehensive review of these applications in three key scenarios of petroleum engineering, namely hydraulic fracturing and acidizing, chemical flooding and gas flooding, and water injection. This article first introduces the steps and methods of machine learning processing in these scenarios, then discusses the advantages, disadvantages, existing challenges, and future prospects of these machine learning methods. Furthermore, this article compares and contrasts the strengths and weaknesses of these machine learning methods, aiming to help researchers select and improve their methods. Finally, this paper identifies some potential development trends and research directions of machine learning in petroleum engineering based on the current issues. [ABSTRACT FROM AUTHOR]

Technologies used in the transport sector have a substantial impact on air pollution and global warming. Due to the immense impact of air pollution on Earth, it is crucial to investigate novel ways to reduce emissions. One way to reduce pollution from ICE is to use alternative fuels. However, blends of alternative fuels in different proportions are known to improve some emissions' parameters, while others remain unchanged or even worsen. It is therefore necessary to find ways of reducing all the main pollutants. For SI engines, mixtures of hydrogen and natural gas can be used as alternative fuels. The use of such fuel mixtures makes it possible to reduce CO, HC, and CO2 emissions from the engine, but the unique properties of hydrogen tend to increase NOx emissions. One way to address this challenge is to use port water injection (PWI). This paper describes studies carried out under laboratory conditions on an SI engine fuelled with CNG and CNG + H2 mixtures (H2 = 5, 10, 15% by volume) and injected with 60 and 120 mL/min of water into the engine. The tests showed that the additional water injection reduced CO and NOx emissions by about 20% and 4–5 times, respectively. But, the results also show that water injection at the rate of 120 mL/min increases fuel consumption by between 2.5% and 7% in all cases. [ABSTRACT FROM AUTHOR]

Internal combustion engines have played a crucial role in the advancement of society. Consequently, there has been a persistent need to enhance their efficiency and performance. The water-injected six-stroke engine is based on conventional four-stroke engines, producing additional power by injecting water into the hot combustion products during the expansion stroke, thereby increasing the overall engine efficiency. However, a comprehensive review that consolidates existing knowledge and identifies future research opportunities in six-stroke engine technology is lacking. This study addresses this gap by thoroughly examining the thermodynamic operation of six-stroke engines and analyzing the impact of water injection on engine performance. The review covers literature from 1994 to 2023, categorizing studies based on the modeling approach, working fluid, thermodynamic cycle, and consideration of heat transfer. Among the 18 analyzed articles, predominantly published from 2015 to 2019, half utilize analytical models, while the rest employ experimental models addressing heat transfer losses. Notably, water injection exhibits a substantial influence, manifesting as a 5.18% increase in brake power and a 1.55% enhancement in thermal efficiency, particularly with acetylene as the working fluid. Finally, a literature overview of water injection in hot gas environments within the engine cylinder was conducted in addition to a preliminary thermodynamic analysis of the Otto and Diesel cycles to compare different configurations outlined in the literature. The lack of studies, experimental setups, and non-idealized models that consider factors such as heat transfer or water evaporation during injection is evident. By critically synthesizing the available literature, this study offers valuable insights into the potential advantages, limitations, and prospects of six-stroke engine studies. [ABSTRACT FROM AUTHOR]

The use of compression ignition engines (CIEs) is associated with increased greenhouse gas emissions. It is therefore necessary to research sustainable solutions and reduce the negative environmental impact of these engines. A widely studied alternative is the use of H2 in dual-fuel mode. This review has been developed to include the most recent studies on the subject to collect and compare their main conclusions on performance and emissions. Moreover, this study includes most relevant emission control strategies that have not been extensively analyzed in other reviews on the subject. The main conclusion drawn from the literature is the negative effect of the addition of H2 on NOx. This is due to the increase in temperature during combustion, which increases NOx formation, as the thermal mechanism predominates. Therefore, to reduce these emissions, three strategies have been studied, namely exhaust gas recirculation (EGR), water injection (WI), and compression ratio (CR) reduction. The effect of these techniques on NOx reduction, together with their effect on other analyzed performance parameters, have been deeply analyzed. The studies reviewed in this work indicate that hydrogen is an alternative fuel for CIEs when used in conjunction with techniques that have proven to be effective in reducing NOx. [ABSTRACT FROM AUTHOR]

• A cascade high-temperature heat pump to produce 1 MW steam at 160 °C is proposed. • District heat is introduced as available heat source for the proposed HTHP system. • Use of alternative low GWP hydrocarbons in the low-temperature loop are examined. • Water injected compressor delivers steam by just 0.9 K superheat directly to sink. • The proposed HTHP shows a better business case compared to the conventional boilers. This work aims to assess and optimize the performance of cascade high-temperature heat pump (HTHP) integrated with district heating (DH) to produce 1 MW steam at 160 °C for the industrial processes. The heat available in the primary loop of the DH network at 80 °C is considered as the heat source; which is cooled down 70 °C through the HTHP evaporator, before supplying the DH secondary loop. The use of alternative hydrocarbons in the low-temperature loop are examined; and considering the gas compressor limitation, the HTHP performance of using each refrigerant is optimized and compared to each other. The optimization results reveal that pentane- hydrocarbon with the highest critical temperature- is the most promising refrigerant to be paired with steam in the high-temperature loop, reaching the highest COP of 2.66. However, concerning safety and compressor sizing issues, butane is an excellent candidate; with volumetric heating capacity (VHC) of about two times more than that of pentane, in the expense of just about 4 % reduction in the HTHP COP. In addition, water injection theoretically controls the steam compressor discharge temperature successfully, with just 0.9 K superheating at the compressor outlet; and reduces its power consumption and the HTHP COP up to 4.3 % and 1.7 %, respectively. Moreover, techno-economic analysis demonstrates that the HTHP technology shows a better business case compared to the conventional natural gas and electric boilers. [ABSTRACT FROM AUTHOR]

Hydrogen stands out as a compelling alternative to fossil fuels for combustion engines. Predictive combustion models are instrumental in developing hydrogen-fuelled engines. A fundamental metric of these models is the laminar burning velocity (LBV), which can be precisely determined through laminar flame propagation simulations. In this context, the selection of an appropriate combustion mechanism is critical. This paper aims to propose the appropriate combustion mechanism for calculating LBV in predictive combustion models of hydrogen-fuelled engines. 15 state-of-the-art combustion mechanisms were applied to reproduce the LBV measurements in engine-like conditions, especially considering the application of lean combustion and water injection. The FFCM 1.0 mechanism was identified from them and further optimised to improve its prediction accuracy at elevated pressures for the lean mixture. The maximum deviation of LBV was reduced from 17.6 % to 8.7 % by this optimisation, in comparison to 10.5 % for its closest competitor mechanism, ELTE (Varga et al., 2015). • 15 combustion mechanisms were selected as the candidates for optimisation. • Test cases consider applications of lean combustion and water injection. • Many mechanisms predict laminar burning velocities at elevated pressure inadequately. • FFCM 1.0 mechanism was optimised to a new mechanism for modelling H2-fuelled engines. • Prediction errors of laminar burning velocity by the new mechanism are within 8.7 %. [ABSTRACT FROM AUTHOR]

It is necessary to improve oil production from reservoirs. Various methods have been proposed to increase oil extraction from reservoir. Each method has specific challenges. In this research, the effect of water and gas injection in to Azadegan reservoir has been analyzed. Azadegan oil field is located south of Iran. In this study, water, immiscible gas and water alternating gas injected to reservoir and its effect on enhanced oil recovery have been investigated. Finally, a comparison between results of methods is provided. Results show that effective method for enhanced oil recovery is immiscible gas injection with 46% oil production efficiency and water alternating gas injection with 36% oil production efficiency. This study shows that oil production efficiency can be increased if duration of gas injection is increased. This study shows, increasing viscosity of water in water alternating gas scenario did not improve the production of Azadegan reservoir. [ABSTRACT FROM AUTHOR]

The work proposes the design of a novel internal combustion engine developed to benefit from the availability on board of cryogenic pressurized hydrogen and oxygen to serve a mechanical propulsion system. The rationale behind the design, as well as the results of simulations, are presented. The two-stroke engine uses direct injection of hydrogen, oxygen, and water, and downstream power turbines, to deliver power densities above 220 kW/L, zero-emission of nitrous oxides and carbon dioxide, and efficiency above 0.70. The novel engine could be an alternative to fuel cell electric propulsion systems, delivering in addition to better hydrogen fuel efficiency, also reduced weight and space of the complete propulsion system. • The availability of pressurized oxygen and hydrogen permit the design of high-efficiency engines. • A high-efficiency 2-stroke engine using oxy-hydrogen combustion is modeled. • The engine also feature water injection and two power turbines. • Computational results for this engine show the opportunity to achieve efficiency above 70%. • This is better than current fuel cells plus electric motors at a reduced weight and volume. [ABSTRACT FROM AUTHOR]

Experimental methods, including mercury pressure, nuclear magnetic resonance (NMR) and core (wateroil) displacement, are used to examine the effects of high-multiple water injection (i.e. water injection with high injected pore volume) on rock properties, pore structure and oil displacement efficiency of an oilfield in the western South China Sea. The results show an increase in the permeability of rocks along with particle migration, an increase in the pore volume and the average pore throat radius, and enhanced heterogeneity after high-multiple water injection. Compared with normal water injection methods, a high-multiple water injection is more effective in improving the oil displacement efficiency. The degree of recovery increases faster in the early stage due to the expansion of the swept area, and the transition from oil-wet to water-wet. The degree of recovery increases less in the late stage due to various factors, including the enhancement of heterogeneity in the rocks. Considering both the economic aspect and the production limit of water flooding, it is recommended to adopt other technologies to further enhance oil recovery after 300 PV water injection. [ABSTRACT FROM AUTHOR]

The Triassic massive sandstone reservoir in the Tahe oilfield has a strong bottom-water drive and is characterized by great burial depth, high temperature and salinity, a thin pay zone, and strong heterogeneity. At present, the water-cut is high in each block within the reservoir; some wells are at an ultrahigh water-cut stage. A lack of effective measures to control water-cut rise and stabilize oil production have necessitated the application of enhanced oil recovery (EOR) technology. This paper investigates the development and technological advances for oil reservoirs with strong edge/bottom-water drive globally, and compares their application to reservoirs with characteristics similar to the Tahe oilfield. Among the technological advances, gas injection from the top and along the direction of structural dip has been used to optimize the flow field in a typical bottom-water drive reservoir. Bottom-water coning is restrained by gas injection-assisted water control. In addition, increasing the lateral driving pressure differential improves the plane sweep efficiency which enhances oil recovery in turn. Gas injection technology in combination with technological measures like channeling prevention and blocking, and water plugging and profile control, can achieve better results in reservoir development. Gas flooding tests in the Tahe oilfield are of great significance to identifying which EOR technology is the most effective and has the potential of large-scale application for improving development of deep reservoirs with a strong bottomwater drive. [ABSTRACT FROM AUTHOR]

It is easy to form a coupling effect between ground stress and gas, and cause the accident of coal and gas outburst dominated by ground stress during deep mining. In order to improve the accuracy of mine gas disaster prevention, it is urgent to deeply understand the influence of water intervention on the desorption characteristics of gas-containing coal under ground stress. A simulation test device was set up for the effect of water injection on the gas desorption characteristics of coal under overburden stress and water injection by applying overburden stress and injecting water at the same time to the experimental coal sample. Based on the experimental setup, the gas desorption data of coal samples from Guhanshan Mine (GHS) were tested at overburden stresses of 5 MPa, 10 MPa and 15 MPa, moisture content of 0%, 2%, 4% and 6%, and the same inflation amount. By analyzing the experimental data, the influence of overburden stress and water injection on the cumulative gas desorption amount, gas desorption rate, initial gas desorption rate influence coefficient and residual gas content of GHS coal samples was obtained. The result shown that the overburden stress effect increased the cumulative desorption amount and the initial gas desorption rate of the dried coal samples, which promoted gas desorption. With the intervention of water, the cumulative gas desorption amount and initial gas desorption rate of coal samples with large overburden stress became smaller, indicating that the moisture inhibited gas desorption, and the overburden stress effect transitioned from promoting to inhibiting gas desorption. Theoretical analysis shown that the piston effect of overburden promoted gas desorption of dried coal sample. As moisture intervention, it produced a strong capillary resistance in the pores and cracks of coal. With the increasing overburden stress, the coal sample was crushed and compacted, and the capillary resistance became larger as the pore fissures got smaller, resulting in a stronger inhibition of desorption. The experimental results have certain positive significance for an in-deep understanding of the mechanism of hydrodynamic measures to prevent coal and gas outburst.

The energy release process of the Mg-based hydroreactive fuels directly affects the performance of water ramjet engines, and the burning rate is one of the key parameters of the Mg-based hydroreactive fuels. However, there is not enough in-depth understanding of the combustion process of Mg-based hydroreactive fuels within the chamber of water ramjet engines, and there is a lack of effective means of prediction of the burning rate. Therefore, this paper aims to examine the flame structure of Mg-based hydroreactive fuels with a high metal content and analyze the impact of the water injection velocity and droplet diameter on the combustion property. A combustion experiment system was designed to replicate the combustion of Mg-based hydroreactive fuels within water ramjet engines, and the average linear burning rate was calculated through the target line method. On the basis of the experiment, a combustion–flow coupling solution model of Mg-based hydroreactive fuels was formulated, including the reaction mechanism between Mg/H2O and the decomposition products from an oxidizer and binder. The model was validated through experimental results with Mg-based hydroreactive fuels at various pressures and water injection velocities. The mean absolute percentage error (MAPE) in the experimental results was less than 5%, proving the accuracy and validity of the model. The resulting model was employed for simulating the combustion of Mg-based hydroreactive fuels under different water injection parameters. The addition of water injection resulted in the creation of a new high-temperature region, namely the Mg/H2O non-premixed combustion region in addition to improving the radial diffusion of the flame. With the increasing water injection velocity, the characteristic distance of Mg/H2O non-premixed combustion region is decreased, which enhances the heat transfer to burning surface and accelerates the fuel combustion. The impact of droplet parameters was investigated, revealing that larger droplets enhance the penetration of the fuel-rich gas, which is similar to the effect of injection velocity. However, when the droplet size becomes too large, the aqueous droplets do not fully evaporate, resulting in a slight decrease in the burning rate. These findings enhance the understanding of the mechanisms behind the burning rate variation in Mg-based hydroreactive fuels and offer theoretical guidance for the optimal selection of the engine operating parameters.