Currently, energy generation based on fossil fuels is producing negative environmental impacts; two of the main symptoms of these impacts are water pollution and climate change. Consequently, the search for new technologies to satisfy the energy demand must have the goal to minimise possible impacts to the environment. There are alternatives with biofuels and, among them, biodiesel. The cheapest reaction pathway for biodiesel production is the transesterification of triglycerides by methanol in the presence of sodium hydroxide; however, this option can contaminate large volumes of water used in the final leach of the biodiesel product. Therefore, a feasible way of producing this biofuel while simultaneously minimising leaching water will be environmentally friendly and will improve economical savings. The present study developed an experimental design in order to minimise the addition of NaOH during biodiesel production by the basic homogeneous pathway. The best operating conditions we... [more]

Horizontal wells’ multi-section and multi-cluster hydraulic fracturing plays an important role in the efficient development of shale gas. However, the influence of the perforating hole and natural fracture dip angle on the process of hydraulic fracture initiation and propagation has been ignored in the current researches. This paper presents the results related to a tri-axial large-scale hydraulic fracturing experiment under different natural fracture parameters. We discuss the experimental results relating to the near-wellbore tortuosity propagation of hydraulic fractures. Experimental results showed that the triaxial principal stress of the experimental sample was deflected by the natural fracture, which caused significant near-wellbore tortuosity propagation of the hydraulic fractures. The fractures in most rock samples were not perpendicular to the minimum horizontal principal stress after the experiment. As well, the deflection degree of triaxial principal stress direction and the... [more]

The design of a technological complex for microwave processing of organic materials is proposed. The electrodynamic system of an oversized microwave reactor for low-temperature pyrolysis has been developed. The constructive elements of the complex that allow its continuous failure-free operation in conditions of high radiation intensity are described. Based on the prototype of the elaborated reactor, model experiments on microwave pyrolysis of peat were carried out. The elemental composition of the solid fraction was analyzed during the conducted experiments. The possibility of the efficiency enhancement of the proposed processing method and potential applications of the novel technology are discussed.

To reduce emissions and save energy, alternative fuel and dual-fuel mode have been widely applied in the field of diesel engines. The pilot injection has potential to reduce engine vibration noise and pollutant emissions. The effects of a diesel fuel pilot injection strategy on the performance of an ethanol/F-T diesel dual-fuel engine were experimentally investigated on a four-cylinder four-stroke common rail diesel engine modified with an ethanol injection system. The results indicate that the variation in the combustion characteristic parameters with pilot injection timing is nonlinear and the difference is small, while soot, NO, and CO tend to decrease, with an increase in pilot injection timing. With the increase in pilot injection amount, pmax, combustion duration, CO and soot increased; pmax phase and CA50 were closer to TDC; HRRmax and the ignition delay period decreased. The BSFC tends to increase with the increase in pilot injection timing and the increase in pilot injection a... [more]

Understanding the impact of sintering temperature on the physical and chemical properties of Ni-BaCe0.54Zr0.36Y0.1O3-δ (Ni-BCZY) composite anode is worthy of being investigated as this anode is the potential for protonic ceramic fuel cell (PCFC) application. Initially, NiO−BCZY composite powder with 50 wt% of NiO and 50 wt% of BCZY is prepared by the sol−gel method using citric acid as the chelating agent. Thermogravimetric analysis indicates that the optimum calcination temperature of the synthesised powder is 1100 °C. XRD result shows that the calcined powder exists as a single cubic phase without any secondary phase with the lattice parameter (a) of 4.332 Å. FESEM analysis confirms that the powder is homogeneous and uniform, with an average particle size of 51 ± 16 nm. The specific surface area of the calcined powder measured by the Brunauer−Emmett−Teller (BET) technique is 6.25 m2/g. The thickness, porosity, electrical conductivity and electrochemical performance of the screen-prin... [more]

A large number of CO2 emissions caused a serious greenhouse effect, aggravating global warming and climate change. Therefore, CO2 utilization has been a research hotspot, especially after the Paris Agreement, and among the various CO2 utilization technologies, the power-to-gas (PTG) and power-to-liquid (PTL) processes have recently attracted significant attention because they can transform CO2 into fuels and/or chemicals. Considering the lack of detailed information in the literature with regard to process design and economic analysis, we have critically and comprehensively summarized the recent research progresses concerning the PTG and PTL processes. Herein, we mainly focus on the power-to-methane in the case of PTG and the power-to-syncrude, power-to-methanol, and power-to-ethers in the case of PTL. From the technical point of view, the bottleneck problem of PTG and PTL processes is the low system efficiency, which can be improved by heat integration and/or process integration. Mean... [more]

China has focused on the exploration and development of shale gas resources to reduce its reliance on coal and shift to cleaner energy sources. While significant progress has been made in the Sichuan Basin, unlocking the shale gas potential in other regions of South China has proven challenging due to the complex geology and mountainous terrain. In 2021, Well QSD-1 was deployed in southwestern Guizhou and achieved a daily shale gas flow of 11,011 m3 in the Dawuba Formation, marking the first time an industrial gas flow had been obtained from shale gas drilling in the marine strata of the Upper Paleozoic in China. This breakthrough has deepened the understanding of the southern China Carboniferous marine strata and highlighted key aspects of the formation: (1) Sedimentation occurred in alternating platforms and basins, with most organic-rich shale developed in sloping and basin areas; (2) the formation exhibits favorable static indicators, with a relatively thick section (over 200 m), a... [more]

Twelve crude oil blends prepared from seven individual crude oils and an imported atmospheric residue were characterized through a true boiling point (TBP) distillation analysis and their density. When comparing the measured TBP fraction yields with those estimated through the application of the additive blending rule, it was found that, for four crude oil blends, the additive blending rule was valid, while for the remaining eight crude oil blends, deviations of the measured TBP yields from the estimated ones were bigger than the TBP analysis’s repeatability limits. By the use of intercriteria analysis evaluation of the data for the deviation of the TBP yields from the additive blending rule and the molar excess volume of the crude oil blends, statistically meaningful relations between the delta TBP yields of light and heavy naphtha, as well as vacuum residue with the molar excess volume, were found. The higher the magnitude of the crude oil blend’s molar excess volume, the bigger the... [more]

The outbreak of the COVID-19 pandemic has led construction companies to prioritize the intelligent and optimal scheduling of human resources in construction projects to reduce costs. This study addresses the problem of heterogeneity in human resource scheduling in construction projects, presents a mathematical model with generic human resources as an example, proposes an improved artificial immune system (NAIS) algorithm to solve the problem, and verifies its effectiveness. Experimental results show that the NAIS algorithm achieves the optimal duration of 9 days in just 2 s using the Matrix Laboratory (MATLAB), which is significantly faster than mathematical optimization technique software (CPLEX), thus confirming the feasibility of the NAIS algorithm. Additionally, the average PD values for the NAIS algorithm, calculated for different worker counts, skills, and the number of tasks, were lower compared to the comparison algorithm. Overall, the NAIS algorithm effectively addresses the h... [more]

In today’s human society, diesel generators (DGs) are widely applied in the human energy and electricity supply system due to its technical, operational, and economic advantages. This paper proposes an intelligent nonlinear H2/H∞ robust controller based on the chaos particle swarm gravity search optimization algorithm (CPSOGSA), which controls the speed and excitation of a DG. In this method, firstly, establish the nonlinear mathematical model of the DG, and then design the nonlinear H2/H∞ robust controller based on this. The direct feedback linearization and the H2/H∞ robust control theory are combined and applied. Based on the design of the integrated controller for DG speed and excitation, the system’s performance requirements are transformed into a standard robust H2/H∞ control problem. The parameters of the proposed solution controller are optimized by using the proposed CPSOGSA. The introduction of CPSOGSA completes the design of an intelligent nonlinear H2/H∞ robust controller f... [more]

Emulsions that mix two or more immiscible phases are broadly applied in pharmaceutics, chemistry, and industries. The phase inversion temperature (PIT) method is an emulsifying approach to preparing an emulsion with low energy consumption and cheap equipment. The effects of surfactant characteristics and processes of cooling or heating on the fuel properties of emulsions composed of silicone oil by the emulsifying method, such as mean droplet sizes of the de-ionized water phase, were considered herein. The application of the silicone oil emulsion as engine fuel was first evaluated. The results show that the emulsions added with the polyol surfactant mixture appeared to have a larger mean water-droplet size, a larger number of dispersed water droplets, a wider range of dispersed-water sizes, and lower kinematic viscosity than those with Brij 30 surfactant. Increasing the surfactant concentration of either Tween 20 mixed with Span 80 or Brij 30 surfactant increased kinematic viscosity an... [more]

Multi-stage fracturing of horizontal wells is an indispensable technology to create complex fracture networks, which can unlock production potential and enable commercial productivity for shale gas with low porosity and permeability. Real-time monitoring of fracture networks is essential for adjusting key parameters, mitigating fracturing risks, and achieving optimal fracturing effects. Micro-seismic monitoring technology accurately captures and describes the development of fracture networks by detecting micro-seismic waves generated through rock ruptures, providing valuable insights into the evaluation of post-fracturing. In this study, we first introduced the basic parameters of well X that were obtained by laboratory experiments and logging interpretation, including porosity, gas-bearing properties, mineral composition, rock mechanics, and crustal stress. Then, the hydraulic fracturing scheme was designed on the basis of the geological engineering characteristics of well X. Finally,... [more]

Volumetric expanders are proven to be more suitable for small-scale waste heat recovery applications because of their simplicity, reliability, lower rotational speed and lower cost. Unlike turbines, volumetric expanders can work in the two-phase fluid state, which broadens their application fields. To investigate the two-phase performance of volumetric expanders, a specific twin-screw expander was chosen and modeled. The leakage loss and the suction pressure loss were primary concerns in this research. The two-phase expansion process in the expander is presented in detail using the developed mathematical model with an indicator diagram. The influence of several factors, including inlet vapor quality, rotational speed and intake pressure, are investigated. The influence mechanism of the vapor phase and the liquid phase on expander performance is clarified. In brief, this paper presents an illustrative understanding of the two-phase expansion process in twin-screw expanders.

A microchannel heat exchanger effectively evacuates heat from a confined space. This paper attempts to gain insight into the combinatorial repercussions of simultaneously coupling two factors that affect a microchannel’s performance, of which channel size and micro-insert complexity are the two main contributors. With water as the working fluid, an ANSYS-based numerical analysis was carried out for two distinct channel sizes, 1 and 2 mm, both with and without micro-inserts. The Reynolds numbers varied between 125 and 4992 and between 250 and 9985 for the 1 and 2 mm channels, respectively. For the 2 mm diameter channel, adding micro-inserts raised the overall pressure drop with increased Reynolds number. The inclusion of micro-inserts increased the pressure drop in the 1 mm channel at first, and thereafter the pressure drop decreased. Incorporating micro-inserts into the channel resulted in enhanced heat transfer. The trade-off between enhanced heat transfer performance and a larger pre... [more]

The green chemistry method for nanocatalyst synthesis along with environmentally feasible non-edible sources are promising alternatives to fossil fuels. The current study focuses on the synthesis of copper oxide phyto-nanocatalyst and the identification of a new renewable feedstock, Citrullus colocynthis, to reduce environmental pollution. The highest biodiesel yield (95%) was obtained under optimum conditions of a 1:8 oil-to-methanol ratio and reaction temperature of 85 °C for 120 min with a 0.365 wt% catalyst concentration. The phyto-nanocatalyst was synthesized using seed oil cake after extracting oil with the salt of copper (copper oxide). The catalyst was then subjected to various analyses, namely, EDX, FT-IR, SEM, and XRD. The catalyst was proved to be efficient and effective after being reused five times and still there was a very small difference in biodiesel yield. All the analyses also show sustainable and stable results. Thus, copper oxide phyto-nanocatalyst with non-edible... [more]

A feasibility study on the mass production of a small wind turbine blade using an injection molding process was conducted. The blade was divided into three sections suitable for injection molding, and the mold was designed and analyzed using Moldflow CAE S/W. The optimal feedstock material was selected through comparison and analysis of three candidate materials. A mold was manufactured to test the injection molding process and evaluate related parameters. The resulting blade was assembled with other components, and a generator was installed to assess its durability, safety, and performance under various conditions. The results indicated the feasibility of producing a blade for a small wind turbine through injection molding, which predicted higher productivity and lower costs compared to traditional manufacturing methods that rely heavily on manual labor.

Third-generation solar cells are designed to achieve high power-conversion efficiency while being low-cost to produce. These solar cells have the ability to surpass the Shockley−Queisser limit. This review focuses on different types of third-generation solar cells such as dye-sensitized solar cells, Perovskite-based cells, organic photovoltaics, quantum dot solar cells, and tandem solar cells, a stacked form of different materials utilizing a maximum solar spectrum to achieve high power conversion efficiency. Apart from these solar cells, other third-generation technologies are also discussed, including up-conversion, down-conversion, hot-carrier, and multiple exciton. This review provides an overview of the previous work in the field, alongside an introduction to the technologies, including their working principles and components. Advancements made in the different components and improvements in performance parameters such as the fill factor, open circuit voltage, conversion efficienc... [more]

The efficiency enhancement of argon power cycle engines through theoretical means has been substantiated. However, the escalation of in-cylinder temperatures engenders abnormal combustion phenomena, impeding the augmentation of compression ratios and practical efficiency. This study presents a comprehensive investigation employing experimental and simulation techniques, aiming to extend the boundaries of thermal efficiency and operational capabilities for hydrogen-powered argon cycle engines. The impact of hydrogen direct injection, intake boost, and port water injection is evaluated in conjunction with an argon power cycle hydrogen engine. The hydrogen direct injection, particularly at an engine speed of 1000 rpm, significantly increases the indicated mean effective pressure from 0.39 MPa to 0.72 Mpa, surpassing the performance of the port hydrogen injection. Manipulating the hydrogen direct injection timing results in the formation of a stratified mixture, effectively attenuating the... [more]

Consumption of photovoltaic solar panels is expected to increase, so the growing amount of end-of-life (EOL) solar panels will require large spaces for their disposal, which at the moment costs around 200 euros/ton. Thus, a proper treatment technique to recover secondary materials from this waste, which are mainly copper, aluminum, silicon, high-transmittance glass, and plastics, must be developed. The last three components are strongly attached to each other; hence, their detachment is necessary for recovery. To achieve this objective, a chemical route was chosen; in fact, solvent extraction is highly recommended, as it has a high separation efficiency. In this study, D-limonene as a bio-solvent was examined for detaching different components of solar panels from each other. A high efficiency for ethylene vinyl acetate (EVA) dissolution and components’ detachment under different conditions was achieved with the help of sonication power. The effects of sonication power, thermal pre-tre... [more]

To address the growing problem of pollution and global warming, it is necessary to steer the development of innovative technologies towards systems with minimal carbon dioxide production. Thermal storage plays a crucial role in solar systems as it bridges the gap between resource availability and energy demand, thereby enhancing the economic viability of the system and ensuring energy continuity during periods of usage. Thermal energy storage methods consist of sensible heat storage, which involves storing energy using temperature differences; latent heat storage, which utilizes the latent heat of phase change materials; and thermochemical heat storage, which utilizes reversible chemical reactions through thermochemical materials. The objective of this review paper is to explore significant research contributions that focus on practical applications and scientific aspects of thermal energy storage materials and procedures. For each type of storage, different materials have been examine... [more]

The Renovation Wave for Europe initiative aspires to materialize the progressive greening of 85−95% of the continental older building stock as part of the European Green Deal objectives to reduce emissions and energy use. To realistically predict the energy performance even for a single apartment building is a difficult problem. This is because an apartment unit is inherently a customized construction which is subject to year-round occupant use. We use a standardized energy consumption response approach to accelerate the setting-up of the problem in pertinent energy engineering terms. Nationally instituted Energy Performance Certification databases provide validated energy consumption information by taking into account an apartment unit’s specific shell characteristics along with its installed electromechanical system configuration. Such a pre-engineered framework facilitates the effect evaluation of any proposed modifications on the energy performance of a building. Treating a vast bu... [more]

Turbine energy recovery is a process energy saving technology, and understanding turbine efficiency has important operational and economic benefits for the operator of a power plant. There are three main areas of research into turbine energy efficiency: the structural performance of the turbine itself, the configuration of the recovery device and the regulation of operating conditions. This paper summarizes recent research advances in hydraulic turbine energy efficiency improvement, focusing on the design factors that can affect the overall efficiency of a hydraulic turbine. To quantify the impact of these factors, this paper investigates the effects of surface roughness, flow rate, head and impeller speed on overall efficiency. Methods for optimizing improvements based on these design factors are reviewed, and two methods, the Box−Behnken Design method and the NSGA-II genetic algorithm, are described with practical examples to provide ideas for future research.

The utilization of natural gas hydrates as an alternative energy source has garnered significant attention due to their proven potential. Despite the successful offshore natural gas hydrate production tests, commercial exploitation has not been achieved. This study aims to enhance the understanding of gas production behavior through simulations from a single vertical well in the Nankai Trough and assess the effectiveness of the step-wise depressurization method for gas production using TOUGH + HYDRATE. The simulation results showed that the effective permeability for the water phase decreased as the hydrates were decomposed, and the invasion of the pore water from the underburden eliminated this effect. Compared with the direct depressurization method, the step-wise depressurization method significantly increased the cumulative gas production by more than 10% and mitigated the rapid generation of gas and water production during the moment of depressurization. The results also indicated... [more]

For further resource utilization of solid waste steel slag and the reduction in biodiesel production costs, this study used steel slag as a carrier to synthesize a CaO-CeO2/slag solid base catalyst for the effective transesterification of palm oil into fatty acid methyl esters (FAMEs). The synthesis involved a two-step impregnation of steel slag with nitrate of calcium and cerium and thermal activation at 800 °C for 180 min. Then, the catalysts’ textural, chemical, and CO2 temperature-programmed desorption properties were characterized. The catalytic activity depended highly on the ratio of Ca-Ce to steel slag mass; the CaO-CeO2/slag-0.8 catalyst showed outstanding performance. Characterization showed that the surface area and total basicity of the Ca-Ce/slag-0.8 catalyst were 3.66 m2/g and 1.289 mmol/g, respectively. The reactivity results showed that FAMEs obtained using 7 wt.% catalyst, 9:1 of methanol-to-palm-oil molar ratio, 180 min reaction duration, and 70 °C reaction temperatur... [more]

This study compares ripple port, stacked switched capacitor, and capacitive energy storage architectures for active power decoupling, comparing the number of components, performance, energy density, DC-link capacitor reduction, efficiency, and frequency operation to highlight their main benefits and drawbacks for single-phase grid-connected applications. The overview reveals equivalent effective energy density without electrolytic capacitors, as well as enhanced simplicity, performance, and durability, thereby providing stacked switched capacitors as an attractive power-decoupling alternative for multi-stage connected applications, based on the principle that its individual buffer capacitors absorb and deliver energy without tightly constraining their individual terminal voltages, while maintaining a narrow range voltage at the buffer DC port.