Configuring energy storage devices can effectively improve the on-site consumption rate of new energy such as wind power and photovoltaic, and alleviate the planning and construction pressure of external power grids on grid-connected operation of new energy. Therefore, a dual layer optimization configuration method for energy storage capacity with source load collaborative participation is proposed. The external model introduces a demand-side response strategy, determines the peak, flat, and valley periods of the time-of-use electricity price-based on the distribution characteristics of load and new energy output, and further aims to maximize the revenue of the wind and solar storage system. With the peak, flat, and valley electricity price as the decision variable, an outer optimization model is established. Based on the optimized electricity price, the user’s electricity consumption in each period is adjusted, and the results are transmitted to the inner optimization model. The inter... [more]

The mechanism of high-intensity conditioning (HIC) has not been thoroughly revealed, and therefore this work investigates the effect of HIC on the surface hydrophobicity of coal with different particle sizes and the possible formation of particle−bubble clusters. The results show that different HIC conditions are required for coarse and fine particles. Coarse particles (+75 μm) require a higher turbulence intensity to increase collector dispersion, thereby increasing the adsorption of the collector. Fine particles (−75 μm) require a lower turbulence intensity to reduce the desorption of the collector. In this study, the optimum HIC conditions for coarse and fine particles are “2200 rpm + 1 min” and “1300 rpm + 1 min”, respectively. Interestingly, it seems that the adsorption capacity between fine particles and the collector is weaker than that for coarse particles. A non-enclosed HIC system produces up to 1.78 × 104/g bubbles in coarse particle−bubble clusters, and the mean bubble diam... [more]

Thermoelectric technology is an effective strategy to convert low−grade waste heat to electrical energy directly. Thermoelectric generators (TEGs) have been extensively studied in various waste heat scenarios, such as vehicle exhaust, metal casting processes and more. However, industrial pipelines also possess high levels of heat and wide distribution, yet there is limited research on TEGs for use in these pipes. The challenge in designing a TEG lies in the heat collector, which is complicated by the distinct structural differences between pipe and plate−shaped TEMs. Ultimately, we propose an arch bridge−shaped heat collector for the pipe to recover wasted thermal energy. The effects of some key factors, such as topology of TEMs, heat source temperature, cooling water temperature and velocity, on the generating performance are studied. The TEG achieved a temperature difference of 65.98 °C across the two ends of the TEM, resulting in an output power of 17.89 W at an open−circuit voltage... [more]

Underground coal mining is a challenging and hazardous occupation that requires constant monitoring of environmental parameters to ensure the safety of miners. A handful of research has been carried out in developing wireless monitoring devices to monitor underground mine workings using Wi-Fi and ZigBee, which has limitations such as limited range, interference, reliability, power consumption, and security. The main objective of this study is to develop an Underground Gas Monitoring Device using LoRa communication for the effective transmission of monitored data. The testing was carried out in an underground mine model to measure the propagation of the LoRa signal with a line of sight and non-line of sight. It was observed that the system performs fairly well in both situations. During testing, it was observed that there was a drop in RSSI at 14 m for non-line of sight, and beyond 17 m no signal was received. Hence, for every 15 m, a booster is required to be placed to maintain efficie... [more]

With the increasing mining depth, the dynamic disaster of coal and gas outbursts in coal mines has become increasingly prominent, and the bursting liability of coal and rock mass in deep coal seam mining is a necessary condition for the occurrence of rock burst and an important index to measure the failure of coal and rock mass. Thermal damage leads to rock instability and failure, which seriously influences the safe and efficient operation of coal mines. To investigate the effect of thermal damage on the bursting liability of deep coals, the burst tendency index of standard coal was measured after subjecting it to thermal damage at different temperatures. The effects of different thermal damage temperatures on the uniaxial compressive strength index, dynamic failure duration, stiffness ratio index, effective impact energy index, residual energy index change rate, and impact energy velocity of the coal and the influence of the post-peak failure mode of the coal were evaluated. The resu... [more]

The western mining areas of China, which are rich in coal resources, lack water resources. Large-scale and high-intensity coal mining in China’s western mining areas has led to the loss of groundwater resources. Underground reservoirs in coal mines are an effective means of achieving the protection and utilization of water resources in these western mining areas. One of the important standards for the safety of an underground reservoir in a coal mine involves checking whether the development of cracks in the coal pillar dam body, under the dual stress conditions of overlying strata and lateral water pressure, passes through the coal pillar dam body or its top and bottom plates, forming a seepage channel for mine water. This article focuses on the safety issues associated with coal pillar dams in the underground reservoirs of coal mines. From the perspectives of overlying rock pressure and lateral water pressure on coal pillar dams, mechanical models, numerical calculations, and similar... [more]

Carbon capture and storage (CCS) technology can reduce CO2 emissions by 85 to 95% for power plants and kilns with high CO2 emissions. Among CCS technologies, carbon dioxide capture using steel slag is a method of carbonating minerals by combining oxidized metals in the slag, such as CaO, MgO, and SiO2, with CO2. This study assessed the amount of CO2 captured and the sequestration efficiency in operating a mineral carbonation plant with a CO2 capture capacity of 5 tons/day by treating the exhaust gas from a municipal waste incinerator and identified the characteristics of the mineral carbonation products. As a result, the average concentration of CO2 in the inflow and outflow gas during the reaction time was 10.0% and 1.1%, respectively, and the average CO2 sequestration efficiency was 89.7%. This resulted in a conversion rate of CaO of > 90%. This study manifested that mineral carbonation products are more stable than steel slag as a construction material and are effective at sequester... [more]

Directional long drilling on the roof is an effective gas control measure in the goaf, but there is little research on the stability of the surrounding rock. In this study, the geological conditions of the #4 coal seam in the Tingnan Coal Mine, Shaanxi Province, China taken as the application background, and the deformation characteristics of boreholes under four typical coal and rock conditions were first analyzed based on the Universal Distinct Element Code (UDEC) numerical simulation. Secondly, the stress, strain, and plastic deformation of the rock surrounding the borehole with different diameters were carried out using the Fast Lagrangian Analysis of Continua 3D (FLAC 3D). The effect of the casing on the stability of the borehole was also simulated. The results showed that the borehole stability of coal and mudstone was lower than that of fine-grained sandstone and coarse-grained sandstone. The larger the borehole diameter, the lower the stability. The borehole tended to be unstab... [more]

Ketone compounds are oxidation products of crude oil in the in-situ combustion (ISC) process. Revealing the molecular composition of ketones can provide theoretical guidance for understanding the oxidation process of crude oil and valuable clues for studying the combustion state of crude oil in the reservoir. In this study, low-temperature oxidation (LTO) processes were simulated in thermal oxidation experiments to obtain thermally oxidized oil at different temperatures (170 °C, 220 °C, 270 °C, and 320 °C). A combination of chemical derivatization and positive-ion electrospray (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to analyze the molecular composition of different kinds of ketones (fatty ketones, naphthenic ketones, and aromatic ketones) in the oxidized oils at different temperatures. The results showed that the concentration of aliphatic ketones and aliphatic cyclic ketones in the product oils decreased with the increase in temperature,... [more]

The industrial sector demands 25% of global energy as heat, where one-third is used at temperatures below 150 °C. Nevertheless, the installed solar heating capacity in the industry is only 0.02%, even though the integration of solar heating systems into production processes could significantly reduce fossil fuel consumption at a competitive cost. Among other reasons, this low penetration is due to the final users’ lack of knowledge of solar heating technologies. As a result, a free pre-feasibility assessment tool was developed for non-specialised users to evaluate the possibility of integrating solar heat into their processes using basic information. This tool uses transient simulation to estimate a feasible solar heating system through the parametric optimisation of the solar collection area, thermal storage volume, heat exchange capacity, and solar integration schemes at the supply level and costs. A commercial facility in Mexico was analysed using the developed tool as a case study.... [more]

In the process of fracturing construction in shale gas reservoirs, microseism is a common means and effective method to evaluate the fracturing effect, but it is not suitable for large-scale and large batches due to its high applicability conditions and cost. Therefore, a concise, fast and low-cost post-fracturing effect evaluation method is needed to evaluate the complexity of fractures formed by fracturing in shale gas reservoirs. In this paper, based on the basic theory of the G-function, the free variable μ was introduced to correct the filter loss coefficient with the participation of natural fractures, and thousands of G-function curves were plotted with fracturing data from hundreds of gas wells in the southern Fuling shale gas field in China. Through the feature analysis of the curve morphology, a G-function graphic template conforming to the block was established, which contains four types and eight morphologies. Four characteristic parameters in the G-function curve were sele... [more]

The occurrence of hump instability in pump mode within a pump turbine poses a significant challenge to the safe and stable operation of Pumped Storage Power Plants (PSPP). To achieve more precise numerical simulations, this paper establishes a weakly compressible model of water based on the Tait equation. Using this model, it is discovered that the onset of hump instability is closely linked to an increase in hydraulic losses induced by stalled rotation within the diffuser. Then, a flow control approach employing water injection into the guide vanes of a pump turbine is proposed in order to suppress flow instabilities and optimize the hump region. The findings reveal that the water injection approach can mitigate hydraulic losses, suppress unstable structures, and diminish the pulsation amplitude within the diffuser, ultimately delaying the emergence of the hump region to lower flow mass conditions. This study is helpful in widening the range of the safe and stable operation of pump tu... [more]

Hydraulic fracturing was the main technology to achieve the economic development of conglomerate reservoirs, knowing that the hydraulic fracture propagation mode was of great significance for improving the development of conglomerate reservoirs. This paper proposed a new method to understand the hydraulic fracture behavior based on a hybrid finite-discrete element method. The simulation indicated that a complex fracture network was created near the wellbore in the studied conglomerate reservoir, and hydraulic fracture propagation around the gravel layer was the main failure mode when the hydraulic fracture reached the gravel layer. From the simulations, it was shown that under small differences in horizontal stress and tensile strength, the hydraulic fracture propagated more easily around the gravel layer, while it could cross the gravel under large differences in horizontal stress and tensile strength. Greater tensile strength differences can reduce the complexity of the fracture netw... [more]

Organic-rich mud rocks are being developed on a large scale worldwide, including in the Middle East. The Jurassic Tuwaiq Mountain Formation (TMF) in the Jafurah Basin is a potential world-class unconventional play. Based on a petrophysical evaluation of the Jafurah basin, the TMF exhibits exceptional and unconventional gas characteristics, such as a high total organic content (TOC) and low clay content. Additionally, the TMF is in the appropriate maturity window, indicating that it has reached the required level of thermal maturity to generate hydrocarbons. Plans for the development of the Jafurah unconventional field use multistage hydraulic fracturing technology. The elastic properties of the shale formation, particularly its Young’s modulus and Poisson’s ratio, dictate how the rock responds to stress and deformation. These properties strongly impact the growth of hydraulic fractures in shale formations. Without a comprehensive understanding of the elastic properties, predicting the... [more]

Buildings consume large amounts of energy resources and emit considerable amounts of greenhouse gases, especially existing buildings that do not meet energy standards. Building retrofitting is considered one of the most promising and significant solutions to reduce energy consumption and greenhouse gas emissions. However, finding suitable energy efficiency measures for existing buildings is extremely difficult due to the existence of thousands of retrofit measures and the need to meet various objectives. In this paper, a multi-stage decision framework, including a multi-objective optimization model, and a ranking method are proposed to help decision-makers select the optimal energy efficiency measures. The multi-objective optimization model considers the economic and environmental objectives, expressed as the retrofit cost and energy consumption, respectively. The entropy weight ideal point ranking method, an evaluation and ranking method that combines the entropy weight method and ide... [more]

Natural gas hydrate (NGH) is a kind of clean energy with great potential because of its huge reserves. There are several effective methods for exploiting hydrate sediments such as depressurization, thermal excitation, inhibitor injection and displacement, etc. Among these methods, the combined depressurization and heat injection method is considered a very promising method, which solves the problem of insufficient heat supply during the depressurization process. In this paper, the mechanism of combined depressurization and heat injection exploitation of NGH is analyzed, and the multiphase flow models of the injection well and production well are established, respectively, for the parallel horizontal NGH well production system with this combined method. The multiphase flow laws of fluids in a wellbore were obtained, and the factors affecting the temperature and pressure distributions in the wellbore were analyzed. The results of this study show that gas and water are produced simultaneo... [more]

As societal interest in recycling of plastics increases, modeling thermochemical recycling of vinyl polymers, e.g., via pyrolysis or reactive extrusion, becomes increasingly important. A key aspect remains the reliability of the simulation results with fewer evaluation studies regarding convergence as in the polymerization or polymer reaction engineering field. Using the coupled matrix-based Monte Carlo (CMMC) framework, tracking the unzipping of individual chains according to a general intrinsic reaction scheme consisting of fission, β-scission, and termination, it is however illustrated that similar convergence demands as in polymerization benchmark studies can be employed, i.e., threshold values for the average relative error predictions on conversion and chain length averages can be maintained. For this illustration, three theoretical feedstocks are considered as generated from CMMC polymer synthesis simulations, allowing to study the effect of the initial chain length range and th... [more]

High current rate charging causes inevitable severe heat generation, thermal inconsistency, and even thermal runaway of lithium-ion batteries. Concerning this, a liquid cooling plate comprising a multi-stage Tesla valve (MSTV) configuration with high recognition in microfluidic applications was proposed to provide a safer temperature range for a prismatic-type lithium-ion battery. Meanwhile, a surrogate model with the objectives of the cooling performance and energy cost was constructed, and the impact of some influential design parameters was explored through the robustness analysis of the model. On this basis, the multi-objective optimization design of the neighborhood cultivation genetic algorithm (NCGA) was carried out. The obtained results demonstrated that if the MSTV channel was four channels, the valve-to-valve distance was 14.79 mm, and the thickness was 0.94 mm, the cold plate had the most effective cooling performance and a lower pumping power consumption. Finally, the optim... [more]

In this study, the combustion characteristics of pine needles, pine needle humus, and the co-combustion of these two types of biomass with coal were compared. In addition, the optimization of the combustion performance of coal/humus was assisted through the following studies: (i) the combustion performance of coal/pine needle humus was studied under four different oxygen concentrations (N2, 10%O2/90%N2, 20%O2/80%N2, and 40%O2/60%N2); (ii) the synergistic effect between the humus and coal during combustion was also investigated by adjusting the blending ratio and oxygen content; (iii) the mechanisms of the optimized combustion processes were expounded by kinetics and thermodynamics discussion. The results demonstrated that the combustion characteristics of the coal/humus blends were found to be higher than those of the coal/pine needle blends. The coupling interactions of the oxygen content and blending ratio contributed to the significant synergistic effect between the two fuels, and t... [more]

The electrochemical reduction of pelleted heterophase powder Pd-Nd2O3-CeO2 mixtures was studied in molten LiCl-Li2O (1−1.5 wt%) at 650 °C. The influence of the composition of the mixture, as well as electrochemical factors—i.e., the amount of electricity passed and the cathode potential during electrolysis—were considered. It was found that in the presence of metallic palladium, neodymium and cerium oxides are reduced by lithium released at the cathode and form intermetallic compounds of different compositions. At potentials more positive than the formation of a phase based on liquid lithium at 0.5−0.8 V, CePd3 and NdPd3 intermetallic compounds are present in the reduced product. At potentials close to the formation of liquid lithium, a whole spectrum of intermetallic compounds is synthesized: CePd, NdPd, Ce3Pd4, and Nd3Pd4. The mechanisms of formation of palladium alloys with neodymium and cerium are proposed and considered. The degree of the reduction of lanthanide oxides was calcula... [more]

This paper presents two novel solution approaches for addressing large-scale multi-floor process plant layout problems. Based on the mixed integer linear programming (MILP) model, the first solution approach employs a multi-directional search strategy while the second improves solution efficiency by reducing model size through an iterative framework. Both approaches determine the spatial arrangement of the plant equipment considering equipment-floor allocation, non-overlapping constraints, tall equipment penetrating multiple floors, etc. The computational results indicate that the proposed approaches achieved potential cost savings for four illustrative examples when compared to the previous studies. Finally, engineering experience constraints were included to represent a more complex industrial situation, and their applicability was tested with the last example.

This paper focuses on the combustion mechanism of furan-based fuels synthesized from lignocellulose. The fuel is a binary alternative fuel consisting of 2-methylfuran and 2,5-dimethylfuran derived from furfural. The key reactions affecting the combustion mechanism of this fuel were identified via path analysis, and the initial reaction kinetic mechanism was constructed using a decoupling methodology. Then, a genetic algorithm was used to optimize the initial mechanism. The final skeleton mechanism consisted of 67 species and 228 reactions. By comparing experimental data on ignition delay, component concentration, and laminar flame velocity under a wide range of conditions over various fundamental reactors, it was shown that the mechanism has the ability to predict the combustion process of this fuel well.

Natural gas hydrate reservoir has been identified as a new alternative energy resource which has characteristics of weak cementation, low reservoir strength and shallow overburden depth. Thus, the stability of subsea equipment and formation can be affected during the drilling process. To quantitatively assess the vertical displacement of the formation induced by hydrate decomposition and clearly identify the influence laws of various factors on wellhead stability, this study established a fully coupled thermo-hydro-mechanical-chemical (THMC) model by using ABAQUS software. The important factor that affects the wellhead stability is the decomposition range of hydrates. Based on this, the orthogonal experimental design method was utilized to analyze the influence laws of some factors on wellhead stability, including the thickness of hydrate formation, initial hydrate saturation, overburden depth of hydrate sediment, and mudline temperature. The results revealed that the decomposition of... [more]

The sustained casing pressure (SCP) phenomenon of shale gas and oil wells occurs frequently after fracturing; therefore, in order to assess the cement sheath’s integrity in the vertical well portion, the cement stones were subjected to a compression test under different temperatures and confining pressures to obtain the mechanical parameters of the cement sheath at different well depths. The integrity of the cement ring between the production casing and the intermediate casing was then investigated using the Moore−Coulomb criterion. We also took into account other elements including pump pressure, production casing wall thickness, and cement ring mechanical properties. The results show that (1) the compressive strength, Poisson’s ratio, and Young’s modulus of cement stone vary obviously under different confining pressures and temperature conditions, and the cement stone shows elastic−brittle failure characteristics at 20 °C. The compressive strength, Poisson’s ratio, and Young’s modulu... [more]

To maximize the potential energy utilization of agricultural and forestry wastes and sludge, experimental studies were conducted on the co-gasification characteristics of two types of sludge (municipal sludge, MS; paper-mill sludge, PS) and a typical biomass straw (ST) under CO2 atmosphere. In this paper, the main two stages of the gasification process, the pyrolysis in the low-temperature region and the CO2-gasification in the high-temperature region, were separately studied and analyzed. The experimental results showed that biomass could effectively promote the pyrolysis of the sludge in the low-temperature region and improve the gasification in the high-temperature region. Due to the complex interactions between components, the characteristic parameters presented obvious nonlinear rules during the co-pyrolysis and co-gasification processes. For the MS-ST mixtures, when increasing the ST content, (i) in the pyrolysis process, the initial reaction temperature gradually decreased, but... [more]