This review presents the nucleate/convective boiling performance for a variety of important low global warming potential (LGWP) alternatives to commonly used high-global warming potential (GWP) refrigerants (such as R-134a, R404A, and R-410A, etc.). Efforts are stressed on the assessment of their evaporation pressure drop and heat transfer coefficient (HTC) characteristics. These alternatives include R-1234ze(Z), R-1234ze(E), R-1233zd (E), R-1234ze(E), R-410A, R-1234yf, and R-513A. The authors investigated the thermo-fluid properties within and outside a tube, mini-channel, micro-fin tube, and plate heat exchanger. The investigation of the numerical, experimental, and simulated results revealed that the evaporation pressure drop and HTC characteristics were dependent on a variety of variables. These factors include the working fluid’s thermodynamics and transport properties, the refrigerant’s mass flux, heat flux, saturation temperature, the vapor quality, the conditions and flow patte... [more]

The presence of a liquid electrolyte in dye-sensitized solar cells (DSSCs) is known to limit the time stability of these devices due to leakage and evaporation phenomena. To overcome this issue, gel-state electrolytes may represent a good solution in order to maintain stability and good performances, albeit at lower costs. In the present work, two different kinds of gel-electrolytes, based on poly (methyl methacrylate) (PMMA) and nanoclay agents, were investigated in DSSC-devices sensitized using β-substituted Zn-porphyrins (namely ZnPC4 and ZnPC12) with enveloping alkoxy chains of different lengths, able to produce a coverage of the photoanode surface. The highest power conversion efficiency (PCE) values equal to 1.06 ± 0.04% and 1.55 ± 0.26% were obtained for ZnPC12 (with longer alkoxy chains) with PMMA- and nanoclay-based electrolytes respectively. The properties of the photoanode/electrolyte interface as well as the influence of the gelling agents on the final properties of the obt... [more]

Steam solvent co-injection processes are generating considerable interest in terms of improving heavy oil upgrading in unconventional reservoirs. The characteristics of the opted solvents in the field have not been dealt with in depth. This paper presents a study on selecting the most optimal solvent for the Akan oilfield enhanced oil recovery (EOR). The first step in this work consisted of determining the Akan oil field viscosity, through an elemental and SARA analyses. Next, a set of physical and chemical methods was used to understand the mechanism of solvents’ effect on oil viscosity dynamics. The compositions of the used solvents were analyzed by a gas chromatography-mass spectrometer system equipped with a mass selective detector ISQ (USA). The evidence from the present study suggests that toluene and o-xylene are the most optimal solvents for enhancing the Akan oil recovery and reducing its viscosity. The obtained data demonstrated a higher efficiency of the used solvents on the... [more]

In this study, the problem of the operability of the solar-heat supply system in the cold region of Kazakhstan receiving minimal solar radiation was studied. The importance of this study lies in the question of how a dual-circuit solar installation can work for productivity in the northern regions of Kazakhstan. In the course of the study, an efficiency reduced from the energy efficiency increased by using a transparent glazed window reduced the supply of coolant into the pipe. Cold liquid heat enters the resulting stream, heat transfer increases, and the intermediate walls heat up. In this study, a method was used to determine the thermal characteristics of a glazed flat collector, which contains a brief and accurate description. From the results obtained, it can be concluded that the effectiveness of 2.40 and 2.53 was recognized in this study. It was also investigated that the thermal capacity of the solar collector depends on the thickness of the absorbing layer. Having conducted th... [more]

This Special Issue, entitled “Intelligent Technologies and Processes for Advanced Nuclear Power and Energy Engineering”, was organized by the journal Processes as a way to collect original research articles on the latest developments in intelligent technologies and processes for advanced nuclear power and energy systems [...]

With the characteristics of low fracturing pressure, little damage to the reservoirs, and assuming the role of carbon storage, supercritical carbon dioxide (SC-CO2) fracturing is suitable for the development of unconventional oil and gas resources. Based on the tensile failure mechanism of rocks, this paper establishes a thermal-fluid-solid coupling initiation pressure model for SC-CO2 fracturing. Using this model, the changes in formation temperature and pore pressure near a wellbore caused by invasion of CO2 into the formation are analyzed, as well as the impact of these changes on the tangential stress of reservoir rocks. The field data of SC-CO2 fracturing in a sandstone gas well are used to validate the reliability of the model. The results show that SC-CO2 fracturing can significantly reduce the initiation pressure, which decreases with the increase in fracturing fluid injection rate. The minimum value of tangential stress is located at the well wall, and the direction of tangent... [more]

The surface subsidence caused by underground mining is a spatiotemporal process. The impact of mining on surface structures (houses, highways, railways, dikes, etc.) and structures in rock strata (shafts, roadways, chambers, etc.) is a dynamic process. It is necessary to study the dynamic movement law of the surface and overlying strata in the mining process of the working face to predict the extent of the impact of mining on the aforementioned structures. It provides a reference for pre-reinforcement and post-mining treatment. This paper studies the variation of surface dynamic movement based on the survey line above the working face of Peigou Coal Mine. The numerical simulation model of the overlying strata dynamic movement is established to study the dynamic movement law of rock strata with different depths, and the fitting function of surface and overlying strata dynamic movement is determined. Finally, the subsidence velocity prediction function of the major section of the surface... [more]

Coal mine noise affects human physiology, psychology, and behavior. It causes errors at work and increases accidents. In this study, we built a coal mine noise simulation experiment system. The system not only included an experimental environment simulation system and a physiological indicator test system, but it also added a miners’ working simulation system. This paper aimed to study the effect of different short-term (25 min) noise levels (60 dB, 70 dB, 80 dB, 90 dB, and 100 dB) on human physiology (skin conductivity and heart rate). Critical analysis showed that the stronger the noise intensity is, the shorter the contact time it takes for physiological indicators to present significant changes, and by setting different noises and measuring the skin conductivity and heart rate of human body, it was concluded that the noise level should be reduced to 90 dB to reduce accidents of miners.

With the combustor burning hydrogen, as well as the strongly coupled fuel and cooling system, the configuration of a hydrogen-fueled aero engine is more complex than that of a conventional aero engine. The performance, and especially the dynamic behavior of a hydrogen-fueled aero engine, need to be fully understood for engine system design and optimization. In this paper, both the transient modeling and performance analysis of hydrogen-fueled engines are presented. Firstly, the models specific to the hydrogen-fueled engine components and systems, including the hydrogen-fueled combustor, the steam injection system, a simplified model for a quick NOx emission assessment, and the heat exchangers, are developed and then integrated to a conventional engine models. The simulations with both Simulink and Speedgoat-based hardware in the loop system are carried out. Secondly, the performance analysis is performed for a typical turbofan engine configuration, CF6, and for the two hydrogen-fueled... [more]

Multi-crop plants (fibrous hemp, maize, and faba bean) can potentially be an alternative to wood biomass pellets, but there is no detailed knowledge to support the suitability of this biomass for solid biofuel production. The aim of this study is to analyze and justify the suitability of multi-crop plant biomass for the production of biofuel pellets and to assess the environmental impact of burning them. This paper presents studies of physical-mechanical, thermal, and chemical characteristics of biofuel pellets from multi-crop plants and emissions during their combustion under laboratory conditions. The main parameters of the produced pellets were determined according to international standards, which are detailed in the methodology part. The length of the produced pellets ranged from 17.6 to 26.6 mm, and the diameter was about 6 mm. The density of wet pellets varied from 1077.67 to 1249.78 kg m−3. The amount of ash in the pellets varied from 5.75% to 8.02%. Determined lower calorific... [more]

In recent years, the reports presented on climate change and its consequences highlight the need to create public policy agendas that address the problem of adaptation and mitigation of anthropogenic greenhouse gas (GHG) emissions. Globally, the energy sector is responsible for a significant percentage of GHG emissions, while it is one of the most important sector for economic growth. In particular, the electricity sector in Mexico relies heavily on fossil fuels for electricity generation. This problem has made it essential to design plans and policies that contribute to GHG mitigation. The General Law on Climate Change, whose objective is to determine the guidelines towards a low-carbon economy, has established a goal of reducing emissions by 50% by 2050 concerning the baseline from the year 2000 and proposes to produce 50% of electricity with clean energy by 2050 following the Mexican Energy Transition Law. For this reason, the challenge is to design and develop an environmentally su... [more]

An experimental investigation of the characteristics and transformation mechanism of Jimsar oil shale and derived shale oil was conducted using a solid-state nuclear magnetic resonance spectrometer (13C NMR), Fourier transform infrared spectroscopy (FT-IR), liquid 1H NMR, and gas chromatography-mass spectrometry (GC-MS) techniques. The carbon skeleton structure of Jimsar oil shale is mainly composed of aliphatic carbons (70.5%), mostly containing straight-chain methylene (CH2), and aromatic carbon (29.31%). Derived shale oil is primarily made of aliphatic compounds that are dominated by n-alkanes and alkenes (comprising more than 70%). The nature of the conversion of oil shale to shale oil is the decomposition of aliphatic groups dominated by methylene structures in organic matter. Additionally, as the heating rate is increased, the secondary cracking reactions in shale oil could increase the contents of short-chain alkanes and alkenes, which could then enhance the secondary polymeriza... [more]

With the continuous improvement of medical testing and instrumentation engineering technologies, the design, testing and development methods of in vitro diagnostic instruments are developing rapidly. In vitro diagnostic instruments are also gradually developing into a class of typical high-end medical equipment. The design of in vitro diagnostic instruments involves a variety of medical diagnostic methods and biochemical, physical and other related technologies, and its development process involves complex system engineering. This paper systematically organizes and summarizes the design, testing and development methods of in vitro diagnostic instruments and their development in recent years, focusing on summarizing the related technologies and core aspects of the R&D process, and analyzes the development trend of the in vitro diagnostic instrument market.

Nowadays, oil companies employ nanofluid flooding to increase oil production from oil reservoirs. Herein the present work, a multiphase flow in porous media was used to simulate oil extraction from a three-dimensional porous medium filled with oil. Interestingly, the finite element method was used to solve the nonlinear partial differential equations of continuity, energy, Darcy’s law, and the transport of nanoparticles (NPs). The proposed model used nanofluids (NFs) empirical formulas for density and viscosity on NF and oil relative permeabilities and NP transport equations. The NPs thermophysical properties have been investigated and compared with their oil recovery factor (ORF) to determine the highest ORF. Different NPs (SiO2, CuO, and Al2O3) were used as the first parameter, keeping all parameters constant. The simulation was run three times for the injected fluid using the various NPs to compare the effects on enhanced oil recovery. The second parameter, volume fraction (VF), has... [more]

Inadequate staffing and long waiting times in hospital emergency rooms are key concerns that can have a negative impact on patient safety and health, as well as the hospital’s overall performance. The purpose of this paper is to investigate the scope of combining the DMAIC (define, measure, analyze, improve, and control) methodology with discrete event simulation and to explore its successful deployment in the Jordanian healthcare sector. The study discussed in this paper is based on a case study conducted utilizing the DMAIC and simulation technique and its application in reducing waiting time and enhancing overall system efficiency in Jordan’s Princess Rahma hospital’s pediatric emergency department. The study shows improvements in the performance of the process and thus productivity in the emergency department through adapting the combined Six Sigma DES methodology. The cycle time of the process was reduced by 73% of the present value, while simultaneously enhancing the total perfor... [more]

Aiming at resolving the problem of low assembly accuracy and the difficulty of guaranteeing assembly quality of remanufactured parts, an optimization classification method for the assembly sequence of remanufactured parts based on different accuracy levels is proposed. By studying the characteristics of recycled parts, based on the requirement that the quality of remanufactured products not be lower than that of the assembly quality of new products, the classification selection matching constraints of remanufactured parts are determined, and the classification selection matching optimization models of remanufactured parts with different precision levels is established. An algorithm combining particle swarm optimization and a genetic algorithm is proposed to solve the model and obtain the optimal assembly sequence. Taking the remanufacturing assembling of a 1.4 TGDI engine crank and a connecting rod mechanism as an example, the comparison of quality data shows that this method can effec... [more]

The clean utilization and green development of coal resources have become a research focus in recent years. Underground hydraulic fracturing technology in coal mines has been widely used in roof pressure relief, top coal pre-splitting, gas drainage, roadway pressure relief and goaf disaster prevention. Different in situ stress types cause great differences in the stress field around the boreholes, the critical pressure of the fracture initiation, and the direction of the fracture expansion trend; in addition, the stress shadow effect generated by the superposition of stress fields between boreholes relatively close together has a mutual coupling effect on the evolution of the stress field, the development of the plastic zone, and the crack propagation of the rock mass. Therefore, an effective method to solve the problem is to establish a mechanical model of hydraulic fracturing in boreholes for theoretical calculation, determine the influence mechanism of the crack shadow effect, and d... [more]

In recent years, non-Pt-based ORR catalysts have been developing rapidly and have achieved performance comparable to or even surpassing Pt precious metal catalysts in specific reactions, offering new possibilities for Pt-based catalyst replacement and showing great promise for application. This paper reviews the recent research progress of non-Pt-based fuel cell ORR catalysts. The latest research progress of non-Pt-based ORR SACs (including single metal active site ORR SACs, multi-metal active site ORR SACs, and non-Pt-based noble metal catalyst ORR SACs), non-metallic ORR catalysts, alloy-based ORR catalysts, high-entropy alloy ORR catalysts, and other non-Pt-based fuel cell ORR catalysts are presented in detail. This paper discusses in detail the synthesis methods, characterization means, optimization of performance, and application prospects of these non-Pt-based ORR catalysts. In addition, this review details the excellent performance of these catalysts in terms of compositional an... [more]

Compared to the organic Rankine cycle (ORC), the organic triangle cycle (TC) is simpler in structure and is not limited by pinch point temperature differences. TC has been studied to some extent by previous researchers, such as the selection of working fluid, application, and the design of the expander. However, system optimization and parameter analysis of TC are still rare. The thermodynamic performance of TC internal circulation and TC heat recovery systems are investigated by theoretical analysis and numerical simulation, respectively. The results indicate that the expander inlet temperature T3 and heater inlet temperature T2 are key elements impacting the thermodynamic performance of the TC internal circulation. For the TC heat recovery system, an optimal value of the average heat-capacity flow rate of working fluid Cwf is discovered to output the maximum net power output Wnet. Moreover, the total heat transfer coefficients for the heater (kA)h and condenser (kA)c are discussed in... [more]

Herein, graphene oxide nanosheets (GO) were synthesized and employed as an additive at various proportions to fabricate a novel cation exchange membrane based on grafted cellulose acetate with sodium 4-styrenesulfonate (GCA) via a solution casting method for direct methanol fuel cell (DMFC) applications. The structure of composite membranes has been examined using FTIR, TGA, SEM, and DSC. The physicochemical properties of the GCA/GO membranes, such as ion exchange capacity, water uptake, mechanical and chemical stability, methanol permeability, and proton conductivity, were measured. The inclusion of GO significantly improved the ability to block methanol, contributing to the observed effects. Among the several composite membranes developed, GCA/GO (2 wt.%) had the highest selectivity with a water uptake of 45%, proton conductivity of 5.99 × 10−3 S/cm, methanol permeability of 1.12 × 10−7 cm2/s, and electrical selectivity of 26.39 × 103 Ss/cm3. Simultaneously, the composite membranes’... [more]

The depletion of traditional fossil energy and the resulting environmental pollution forces people to explore new energy sources. Direct use of solar energy is now a viable solution for solving these problems. Covalent organic frameworks (COFs) are a porous crystalline material; their well-defined two-dimensional or three-dimensional frameworks can ensure the orderly arrangement of photoelectric active units, giving them potential photoelectric conversion applications. The tunable structural features endow COFs many advantages in photocatalytic hydrogen production under visible light. This review comprehensively summarizes the research progress on photoelectronic donor−acceptor (D-A) COFs with tunable structure for photocatalytic hydrogen evolution and will provide a feasible guiding strategy for applying this type of COFs in photocatalytic hydrogen production.

A wind−hydrogen coupled power generation system can effectively reduce the power loss caused by wind power curtailment and further improve the ability of the energy system to accommodate renewable energy. However, the feasibility and economy of deploying such a power generation system have not been validated through large-scale practical applications, and the economic comparison between regions and recommendations on construction are still lacking. In order to solve the aforementioned problems, this paper establishes an economic analysis model for the wind−hydrogen coupled power generation system and proposes a linear optimisation-based priority analysis method focusing on the major net present value for regional energy system as well as a cost priority analysis method for hydrogen production within sample power plants. The case study proves the effectiveness of the proposed analysis methods, and the potential to develop wind−hydrogen coupled power generation systems in various provinc... [more]

To investigate the tube thinning of gas wells in the northwestern oilfield, the failed tubing was analyzed by using material property testing, SEM, EDS, and XRD. A novel model that was specific to the service life of tubing in terms of the wall thickness of tubing was established. The model is based on the circumferential stress of tubing. The safety factor against internal pressure and corrosion rate are considered in the model. Our results make clear that the chemical composition, non-metallic inclusion, hardness, and tensile strength of the pipe meet the requirements of relevant standards. The corrosion products on the inner and outer wall of the tubing are mainly FeCO3 and BaSO4, while CaCO3 exists in the outer wall. Additionally, we prove that the corrosion process of the failed tubing is CO2 corrosion. The tubing under the packer suffers from water-accumulation corrosion, and the tubing above the packer suffers from water-carrying corrosion. It is observed that the failed tubing... [more]

This study presents a pointer-driven controller for an instrument panel. The proposed pointer utilizes the permanent magnet (PM) stepping motor produced by the Japanese company NMB. This stepping motor is vibration-proof and tolerates noise jamming as well as wind and rain exposure. Moreover, it has no mechanical structures and is low cost. Most importantly, it features accurate positioning; therefore, it can be used to measure vehicle speed, engine speed, fuel capacity, and temperature. However, the PM stepping motor of the NMB pointer requires 10 degrees for each step, and this low resolution results in roll hesitation as its steps. The aim of the current paper was to solve the problems of the large angle size and low resolution associated with this stepping motor. Based on two-phase excitation, we propose driving the motor using pulse width modulation (PWM). Specifically, we divided each 10-degree step into 100 equal parts. In other words, every step is 0.1 degrees. The resolution o... [more]

The thermal recovery method of steam flooding is one of the most common development methods for heavy oil reservoirs. However, after multiple rounds of steam injection development, the composition of crude oil and reservoir rock properties have changed greatly, which is unfavorable for the subsequent enhanced oil recovery. It is necessary to study the distribution of the remaining oil after the thermal recovery of heavy oil reservoirs, and clarify the change characteristics of the components of the crude oil under different steam injection conditions. At the same time, the change of porosity and the permeability of the rocks after steam flooding, and its influence on oil recovery, are investigated. In this paper, the composition changes of heavy oil before and after steam flooding are studied through experiments and numerical simulation methods. A numerical model is established to study the retention characteristics of heavy components in heavy oil reservoirs by the CMG software. The e... [more]