Energy Science & Engineering最新文献

The effect of particle packing height (10, 30, 50, 70 mm) on the yield and composition of oil shale pyrolysis products is investigated. The results show that the oil yield could decrease 1.0% and the noncondensable gases yield could increase 0.5% as the oil shale packing height increased from 10 to 70 mm. The main hydrocarbon gases are C1–C6 gases, and the increase of packing bed height could decrease the relative content ratio of alkanes to alkenes in hydrocarbon gases. The primary components of the derived oil are aliphatic compounds, aromatic compounds, and compounds containing heteroatoms in the carbon atoms range of C6–C28. And the hydrogen type of shale oil is mainly composed of methylene groups (about 70%) with longer alkyl chains, and CH₃ in aromatics, cycloalkanes, and alkanes. The chemical composition and hydrogen type have certain regularity changes with the changing of packing height, attributing to the effect of temperature gradients between surface and center of packing bed, and the diffusing time of products through the packing bed.

The removal and discharge of coal powders from coalbed methane wellbore is the key to maintaining continuous production. For this reason, based on the submerged jet theory, the force and migration starting conditions of coal powder particles deposited at the bottom of the coalbed methane well are analyzed by analyzing the cohesiveness of coal powders, and a model for the starting and migration of coal powders at the bottom of the well under submerged jet conditions is established; Considering the adhesion between coal dust, the adhesion coefficient is used to characterize the adhesion between particles, a mechanical model of coal dust particles deposited at the bottom of the well is established, and the corresponding calculation formula for the outlet flow rate of the coal dust cleaning nozzle is derived. The fluid mechanics parameters of the bottom of the well coal dust cleaning under different conditions are obtained, and the numerical simulation method is used to simulate the whole process of jet flushing of the bottom of the well coal dust deposited, and the effect of the bottom of the well jet flushing of coal dust deposits is analyzed, providing a theoretical basis for the bottom of the well coal dust flushing process.

In this study, the Structural Units-Bonding Matrix will be introduced into the crude oil characteristics analysis, specifically engineered to depict the molecular intricacies of petroleum substances. This methodology synergizes the bonding matrix with structural units, assigning the bonding matrix to the foundational layer, while the structural units adorn the surface layer. Through meticulous analysis of crude oil data, this study identified the core and branched molecular constituents of crude oil, facilitating the digital articulation of these molecules. Leveraging this foundational work, this study developed composition models for five quintessential types of crude oil, enabling the precise prognostication of their macroscopic physical properties. Further, by evaluating the viscosity-temperature characteristics of these selected crude oils, this study established a predictive model for the viscosity–temperature relationship of crude oils, grounded in the quantitative structure–property relationship method. This approach not only augments this study understanding of crude oil molecular composition but also enhances the predictive accuracy of their physical properties, heralding a significant advancement in the field of petroleum molecular science.

To study the flame propagating characteristic and its coupling effect with other parameters in the LPG pipeline, a typical pipeline model with two equal-length branches perpendicular to each other is designed for experiment and simulation. Then, gas explosion scenarios are experimentally tested and numerically simulated, which is followed by the analysis of flame shape changing with time and peak temperature changing with space. Results show that when passing through the bifurcation, flame propagates to vertical branch B in a sharp knife shape affected by the strong vortex, reflected airflow, and compressed pressure wave in the pipeline with a diameter of 0.125 m. At the monitoring point that is 0.4 m away from the bifurcation point, the peak temperature of the vertical branch B is 57.87% bigger than that of the horizontal branch C, and its arrival time is 80% longer than that of the horizontal branch C, due to the existence of flame in vertical branch B. What's more, in both branches, the coupling results between peak temperature and peak velocity agree very well with the growth function, while the coupling results between peak temperature and peak pressure agree well with the decay function, providing aids to the optimal layout design of industrial pipeline branches as well as to the explosion suppression measures.

Geological carbon storage and utilization is widely regarded as the most realistic method of reducing carbon emissions throughout the energy transition era. In recent times, the implementation of carbon dioxide (CO₂) injection has emerged as a potential method for increasing the recovery of hydrocarbon and facilitating the interaction of CO₂ in shale reservoirs. This methodology enables the mitigation of total carbon emissions released into the earth's atmosphere. The concept of using CO₂ geological sequestration in unconventional shale formations seems to be a prudent approach in responding to both the growing energy demand and mandating environmental requirements simultaneously. Shale reservoirs have received significant interest in the global context because to their substantial reserves and widespread distribution. This research offers a comprehensive analysis of the essential components involved in the sequestration of CO₂ in shales, therefore improving the trapping and long-term storage of CO₂. In addition, it explores the extraction of hydrocarbons in this context. Gaining a comprehensive understanding of the fundamental factors that contribute to the storativity and trappability of CO₂ is crucial for improving the displacement of methane gas (CH₄) during shale gas recovery. This is particularly relevant in depleted the reservoirs of shale gas, where the aim is to enhance the effectiveness of in situ CO₂ sequestration while reducing the leakage risk.

Of the processes that are approved to produce synthetic kerosene for use in jet fuel, about half produce olefinic kerosene that is hydrotreated. The alkene concentration in synthetic kerosene is indirectly regulated through the thermal oxidative stability specification. Perceptions about the deleterious influence of alkenes on thermal oxidative stability suggest that olefinic kerosene must be deeply hydrogenated. The extent of olefin saturation required has economic implications. To evaluate what an acceptable alkene concentration in synthetic kerosene is, the impact of alkene concentration on the outcome of the jet fuel thermal oxidative stability test (JFTOT) performed at 325°C in accordance with the ASTM D3241 standard test method was experimentally evaluated. Model synthetic kerosene mixtures to which different concentrations of alkenes (1-decene, α-methylstyrene, indene) were added, as well as control samples were studied. In the concentration range investigated, up to 10 wt% 1-decene, 5 wt% α-methylstyrene, and 2 wt% indene did not lead to increased fouling in the JFTOT. Fouling passed through a minimum value with increasing alkene concentration and alkene concentration on its own was a poor predictor of thermal oxidative stability. Analysis of the kerosene collected after passing through the JFTOT found measurable changes in density and refractive index. Dissolved oxygen reacting during thermal oxidative stability testing was accounted for mostly in oxygen-containing products in the kerosene boiling range, which indicated that the heavier products were mainly hydrocarbon in nature. In addition to initiation by autoxidation, the investigation also pointed to the existence of a second thermally initiated fouling pathway that does not require the presence of oxygen.

Temperature increases in photovoltaic (PV) panels are one of the primary issues preventing PV systems from being used extensively. When a photovoltaic module overheats, its output power performance drops by 0.4%–0.5% for every degree Celsius above its rated temperature. Lowering the operating temperature of the PV surface using a cooling medium is an efficient technique to increase electrical performance and decrease the rate of thermal degradation of a PV module. To prevent this performance loss, researchers have worked on cooling photovoltaic panels with fluids such as air, water, and nanofluids. In this study, the effects of cooling on photovoltaic panels with water and nanofluid were investigated. The experiment was carried out by fixing the pipe and fins to the back surface of the panel. Al₂O₃-water and TiO₂-water nanofluids were used as working fluid due to their cost effectiveness. Nanofluids prepared in three different volumetric fractions (0.01%, 0.1%, and 1%), the current and voltage values obtained from the panels were recorded, and the panel efficiency was calculated. The experimental results showed that the cooling increased the panel voltage and decreased the current. The results indicated that using TiO₂ nanofluid was more effective than Al₂O₃ nanofluid in terms of electrical efficiency. It was also found that the fluids prepared as 0.01% and 1% gave the most efficient results. It has been observed that it is possible to increase the panel efficiency by 8.32% by cooling the panel.

To address the issues of coal rib instability and high occurrence of roof falls in high extraction height fully mechanized coal mining of soft coal seams, this study comprehensively employs theoretical analysis, numerical calculations, and field industrial experiments. By analyzing the distribution characteristics of coal rib displacement and deformation instability zones under different mechanical parameters of soft coal seams, the instability mechanism of coal ribs in high extraction height mining of thick and soft coal seams is revealed, and corresponding stability control techniques for high extraction height coal ribs and supports are developed. The study shows that the stability of coal ribs in high extraction height mining fields of soft and thick coal seams decreases as the values of mechanical parameters decrease. In other words, the smaller the cohesion and deformation parameters of the coal body, the more prone the coal rib is to roof falls. By utilizing advanced deep-hole static water infusion technology, the frequency of roof falls in extremely soft high extraction height working faces is reduced by 80%, the average depth of roof falls is decreased by 35%, and the average length of roof falls is reduced by 50%. The stability of the coal ribs is effectively improved.

The global energy crisis has been one of the significant challenges for decades, threatening the global economy, and the health of our environment. The government's efforts to enhance the welfare and lifestyle of citizens have been partially undermined by a significant rise in energy intensity, resulting in increased energy consumption. Over the years, researchers have utilized historical energy consumption data to enhance energy efficiency through various technologies. Innovative smart technologies drive energy efficiency, reducing energy usage throughout all areas of the energy industry, from production and supply to consumption. This creates a balance in all sectors and indicates a decrease in energy demand in all areas of building infrastructure. Green buildings that utilize Internet of Things (IoT) technology employ sensors and software to collect data, optimizing, and enhancing building performance. This includes reducing energy and electricity consumption, improving air quality, and optimizing lighting throughout the day. These buildings can contribute to reaching zero-energy building targets. It becomes challenging to manage green buildings without using centralized control. Therefore, managing and integrating these buildings with intelligent technologies is vital in achieving environmentally friendly management. This study offers a broad overview of the green building concept and explores the use of the green IoT in enhancing services and conserving energy within green buildings. The article aims to deliver an extensive review of green buildings and their advantages, analyze the technology behind the IoT and its integration with solar panels to lower energy consumption, and ultimately identify the challenges present in this area of research.