Curing minor leaks and restoring the integrity of a wellbore in a safe and economical way is always challenging in oil and gas production. In this work, a composite pressure-activated sealant, combined with liquid and solid sealing materials, was prepared via the demulsification approach. The structure, morphology, and size distribution of key particulates in the sealant were examined, and the in-situ self-adaptive sealing property was examined with a specially design dynamic sealing detector. The results indicated that the pressure-activated sealant was a multi-dispersed phase system, and the dispersed colloid particles were regular in shape and had a narrow size distribution of 300−400 μm. The solid sealing materials were introduced to construct a composite pressure-activated sealant, and the sealing capability can be markedly reinforced by cooperativity of liquid and solid sealing materials. A mechanochemical coupling model was put forward to rationalize the dynamic sealing process.... [more]

In this study, RF-based un-doped and nitrogen-doped aerogels were produced by polymerisation reaction between resorcinol and formaldehyde with sodium carbonate as catalyst and melamine as the nitrogen source. Carbon/activated carbon aerogels were obtained by carbonisation of the gels under inert atmosphere (Ar) followed by activation of the carbons under CO2 at 800 °C. The BET analysis of the samples showed a more than two-fold increase in the specific Surf. area and pore volume of carbon from 537 to 1333 m2g−1 and 0.242 to 0.671 cm3g−1 respectively after nitrogen doping and activation. SEM and XRD analysis of the samples revealed highly porous amorphous nanostructures with denser inter-particle cross-linked pathways for the activated nitrogen-doped carbon. The X-Ray Photoelectron Spectroscopy (XPS) results confirmed the presence of nitrogen and oxygen heteroatoms on the Surf. and within the carbon matrix where improvement in wettability with the drop in the contact angle from 123° to... [more]

Rock mass is a medium created through processes that have lasted over four billion years, and its intrinsic feature is the variability of the parameters that describe it. A particularly high variability of mechanical parameters is observed in Carboniferous sedimentary and metamorphic rocks. The mechanical properties, especially the rock mass strength, are essential for the design and maintenance of the stability of excavations conducted in it and for the safe conduct of mining operations. This article presents the test results confirming the random variability of the mechanical parameters of the rock mass. The second part of the article presents the results of numerical simulations mapping the Carboniferous rock mass along with a 1000 m deep tunnel excavation protected by steel arch supports. Numerical simulations were carried out for models with different variability coefficients of strength and deformation parameters, and the obtained results were analyzed in terms of damage zones an... [more]

In this study, the process of the solidification of a PCM (phase change material) liquid in an annular space was analytically investigated with the use of a simplified quasi-steady-state model. This model described the phase change phenomenon with the cylindrical solidification front and with the solidification liquid overheated above the solidification temperature. One of the important novelties of the applied model was the determination of the coefficient of the heat transfer between the liquid and the solidified layer on the solidification surface, which was calculated as a function of the location of the solidification front. A method for calculating the variable coefficient of heat transfer on the surface of the solidification front during the solidification process is presented. The contact layer between the cold wall and the solidified layer was incorporated into the model and played an important role. The theoretical analytical method describing the solidification process based... [more]

Lowering the platinum group metal content of oxygen reduction reaction catalysts is among the most prevalent research focuses in the field. This target is herein approached through supported Pd(II) complexes. Starting from a commercial macrocycle, a new ligand is synthesized, its solution behavior and binding properties briefly explored (potentiometry, UV-Vis) and then used to prepare a new catalyst. A supramolecular approach is used in order to obtain homogeneous decoration of carbon nanotubes surfaces, fostering novel possibilities to access single-ion active sites. The novel catalyst is characterized through X-ray photoelectron spectroscopy and scanning transmission electron microscopy and its promising oxygen reduction reaction performance is evaluated via rotating ring-disk electrode and rotating disk electrode in half-cell studies.

In this study, experimental apparatus of desiccant dehumidification was developed at lab-scale, using silica gel as a desiccant material. Experimental data were obtained at various ambient air conditions, while focusing the climatic conditions of Multan (Pakistan). A steady-state analysis approach for the desiccant dehumidification process was used, and thereby the slope of desiccant dehumidification line on psychrometric chart (ϕ*) was determined. It has been found that ϕ* = 0.22 in case of silica gel which is lower than the hydrophilic polymeric sorbent, i.e., ϕ* = 0.31. The study proposed two kinds of systems, i.e., (i) standalone desiccant air-conditioning (DAC) and (ii) Maisotsenko-cycle-assisted desiccant air-conditioning (M-DAC) systems. In addition, two kinds of desiccant material (i.e., silica gel and hydrophilic polymeric sorbent) were investigated from the thermodynamic point of view for both system types, using the experimental data and associated results. The study aimed t... [more]

Chemical composition influences the calorific power of wood, mainly due to the calorific power of structural compounds and extractives. Heat treatment changes the chemical composition of treated wood. This work studies the relationship between chemical composition and calorific power improvement by heat treatment. Samples were heat-treated by the ThermoWood process ® for 1 h and 2 h. High heating value (HHV) and chemical composition; lignin, cellulose, hemicelluloses and extractives in dichloromethane, ethanol, and water were determined. The HHV of untreated wood ranged between 18.54−19.92 MJ/kg and increased with heat treatment for all the tested species. A positive linear correlation was found between HHV and Klason lignin (R2 = 0.60). A negative trend was observed for holocellulose, cellulose, and hemicelluloses content against HHV, but with low determination coefficients for linear regression. The best adjust for polysaccharides was found for hemicelluloses content. A positive corr... [more]

Thermophysical properties of HFE-356mmz in the vapor phase were measured by means of an acoustic-microwave resonance method. HFE-356mmz, which is 1,1,1,3,3,3-hexafluoro-2-methoxypropane in chemical name, is expected to be used as a working fluid with low global warming potential for the Organic Rankine cycle (ORC). The sound velocity and dielectric permittivity were simultaneously measured by using a cylindrical acoustic-microwave resonator. The sound velocity data were analyzed to obtain the ideal-gas heat capacity at constant pressure. The integral of the ideal-gas heat capacity as a function of temperature derives the ideal-gas enthalpy, which is a fundamental and important energy property to simulate the thermodynamic cycle. Similarly, the analysis of the dielectric permittivity data leads to information on the ideal-gas molar polarizability, dipole moment, and density. The acquired thermophysical properties of HFE-356mmz were compared to those of R-245fa and n-pentane, which are t... [more]

A thermal model is proposed to analyze the performance of an indirect solar dryer (ISD) with latent heat storage using phase change material (PCM). The estimations are compared with experimental data presented in the scientific literature taken in real conditions. The validated thermal model is used in order to address a comprehensive analysis of the performance of the ISDs under the same operation conditions, the model is able to estimate the temperatures of glass cover, absorber plate, PCM, useful heat, thermal and storage efficiencies, and variables that are difficult to measure experimentally such as liquid fraction, heat losses, and accumulated energy of the ISDs. Three study cases are considered: Case 1 consists of two collectors with and without alternating nocturnal and diurnal operation (benchmarking case). Case 2 and 3 consist in a unique collector operating continuously for 24 h with PCM and without PCM, respectively. It was determined that the use of PCM in ISD increased th... [more]

The present study explores the entropy generation, flow, and heat transfer characteristics of a dissipative nanofluid in the presence of transpiration effects at the boundary. The non-isothermal boundary conditions are taken into consideration to guarantee self-similar solutions. The electrically conducting nanofluid flow is influenced by a magnetic field of constant strength. The ultrafine particles (nanoparticles of Fe3O4/CuO) are dispersed in the technological fluid water (H2O). Both the base fluid and the nanofluid have the same bulk velocity and are assumed to be in thermal equilibrium. Tiwari and Dass’s idea is used for the mathematical modeling of the problem. Furthermore, the ultrafine particles are supposed to be spherical, and Maxwell Garnett’s model is used for the effective thermal conductivity of the nanofluid. Closed-form solutions are derived for boundary layer momentum and energy equations. These solutions are then utilized to access the entropy generation and the irrev... [more]

This paper presents a detailed geological map at the 1:20,000 scale of the Tocomar basin in the Central Puna (north-western Argentina), which extends over an area of about 80 km2 and displays the spatial distribution of the Quaternary deposits and the structures that cover the Ordovician basement and the Tertiary sedimentary and volcanic units. The new dataset includes litho-facies descriptions, stratigraphic and structural data and new 234U/230Th ages for travertine rocks. The new reconstructed stratigraphic framework, along with the structural analysis, has revealed the complex evolution of a small extensional basin including a period of prolonged volcanic activity with different eruptive centres and styles. The geological map improves the knowledge of the geology of the Tocomar basin and the local interplay between orogen-parallel thrusts and orogen-oblique fault systems. This contribution represents a fundamental support for in depth research and also for encouraging geothermal exp... [more]

Phosphorus (P) recovery from sewage sludge ash (SSA) is one of the most promising approaches of phosphate rock substitution in mineral fertilizers and might be a sustainable way to secure supply of this raw material in the future. In the current investigation, the process of thermochemical treatment of SSA was applied to SSA coming from selected mono-incineration plants of municipal sewage sludge in Poland (Cracow, Gdansk, Gdynia, Lodz, Kielce and Szczecin). The Polish SSA was thermochemically converted in the presence of sodium (Na) additives and a reducing agent (dried sewage sludge) to obtain secondary raw materials for the production of marketable P fertilizers. The process had a positive impact on the bioavailability of phosphorus and reduced the content of heavy metals in the obtained products. The P solubility in neutral ammonium citrate, an indicator of its bioavailability, was significantly raised from 19.7−45.7% in the raw ashes and 76.5−100% in the thermochemically treated S... [more]

A series of impact compression tests were conducted to study the breakage characteristics of magnetite, as well as the impact pressure on its strain rate and dynamic compressive strength. The dynamic mechanical properties and fragmentation size distribution of magnetite under diverse impact loads and cyclic impact were investigated, with fractal theory as a basis and split Hopkinson pressure bar (SHPB). Breakage methods were also employed to analyze the fracture morphology of magnetite. According to the result, the fractal dimension can reflect the distribution of fragments in various sizes. If the strain rate increases, the fractal dimension will be larger, the fragment size will be finer, and the fragmentation degree will be more influential. A micro-analysis of SEM images demonstrates that the fracture morphology is determined by mineral properties. Under low load cyclic impact, intergranular fracture is the main fractography. Besides, the intergranular fracture will be changed to a... [more]

In recent years, graphene-based nanomaterials have been increasingly and widely used in numerous industrial sectors. In the drilling industry, graphene oxide in cement slurry has significantly improved the mechanical parameters of cement composites and is a future-proof solution. However, prior to placing it in a borehole ring space, cement slurry must feature appropriate fluidity. Graphene oxide has a significant influence on rheological parameters. Therefore, it is necessary to study graphene oxide’s influence on the rheological parameters of cement slurries. Thus, this paper presents rheological models and the results of studies on rheological parameters. A basic cement slurry and a slurry with a latex addition were used. The latex admixture was applied at concentrations of 0.1%, 0.03%, and 0.06%. In total, studies were carried out for six slurries with graphene oxide and two basic slurries. The obtained results of studies on the slurries with graphene oxide were compared with the c... [more]

High voltage spark discharge (HVSD) could generate strong pressure waves that can be combined with a rotary drill bit to improve the penetration rate in unconventional oil and gas drilling. However, there has been little investigation of the effect of electrical conductivity on rock damage and the fragmentation mechanism caused by HVSD. Therefore, we conducted experiments to destroy cement mortar, a rock-like material, in water with five conductivity levels, from 0.5 mS/cm to 20 mS/cm. We measured the discharge parameters, such as breakdown voltage, breakdown delay time, and electrical energy loss, and investigated the damage mechanism from stress waves propagation using X-ray computed tomography. Our study then analyzed the influence of conductivity on the surface damage of the sample by the pore size distribution and the cumulative pore area, as well as studied the dependence of internal damage on conductivity by through-transmission ultrasonic inspection technique. The results indic... [more]

Agricultural residue is a readily available biomass source for making biofuels. However, complex structure along with low calorific value makes it reluctant to be utilized. This necessitates the pretreatment of biomass to improve its accessibility. In this study, rice straws were treated with saturated steam at 180−200 °C for 5−10 min and pelletized. Results indicated that the pretreatment process could effectively improve the calorific values and enhance the hydrophobicity of the rice straws. The steam explosion process changed the content of chemical components in the biomass materials. With the increase of reaction temperature and retention time, the content of cellulose, hemicelluloses and lignin declined. Comparedwith the raw materials, there was an increase in the calorific value from 16.24 MJ/kg to 17.26 MJ/kg for the steam treated straws. For moisture sorption test under the condition of 30 °C and 90% relative humidity, the equilibrium moisture content dropped from 21% for untr... [more]

In this paper, we present a new approach for the analysis of the dependence of construction costs on the geometric shape of a building. Instead of difficult or even impossible-to-establish uniform prices and costs, we propose a cost analysis concerning the amount of materials needed for construction. We show that the basic parameters are the base area of the building (plan), assumed in the study as the building area, and the area of the external walls of the building. The amount of consumption of most materials is proportional to the base area and the area of the external walls. The materials required for construction consume large amounts of energy during their manufacture. Therefore, shape optimization is not only economically significant for the investor but is also important in terms of the energy consumption, i.e., embodied energy. We propose a set of indicators to help a designer optimize the shape of the building at the initial design stage.

Hydrate-based CO2 capture from large emission sources is considered a promising process for greenhouse gas mitigation. The addition of nanoparticles may promote or inhibit the formation of hydrates. In this work, CO2 hydrate formation experiments were performed in a dual-cell high-pressure reactor. Non-modified, hydrophilic modified and hydrophobic modified aluminum oxide (Al2O3) nanoparticles at different concentrations were added to assess their promoting or inhibitory effects on CO2 hydrate formation. The equilibrium temperature and pressure, induction time, and total gas consumption during CO2 hydrate formation were measured. The results show that the presence of Al2O3 nanoparticles exerts little effect on the phase equilibrium of CO2 hydrates. Under the experimental conditions, the addition of all Al2O3 nanoparticles imposes an inhibitory effect on the final gas consumption except for the 0.01 wt% addition of hydrophilic modified Al2O3 nanoparticles. The induction time required fo... [more]

In this paper, we developed an effective method for purifying oil sludge using a sorbing electrochemical matrix and assessed the prospects of this method in comparison with conventional hydrocracking. We synthesized Ni-W supported hydrocracking catalysts with different morphology and studied their activity under various conditions, we compared the obtained catalysts with commercial catalyst SGK-5. We demonstrated that the introduction of a secondary mesoporous structure in the catalyst leads to an increase in the yield of light fractions to 52 wt.%. The possibility is demonstrated to obtain hydrocarbons from reservoir oil sludge, dispersed into an aqueous solution of detergent, by the method of low-temperature hydrogenation in sorbing electrochemical matrices. The obtained product was characterized by low viscosity, low content of transition metals (<320 ppm), and sulphur (<260 ppm).

The water distribution subsystem is the most failing subsystem included in the water supply system. One of the main consequences of water supply failures is the lack of water supply to consumers, which is always very onerous. The paper presents a method of determining the conditional probability that a break in the supply of water to consumers of a certain duration will be caused by a specific type of failure. The result of the work was to identify water supply network failures that result in the longest water supply suspension time. The method was presented on a real water supply system. In order to reduce the incidence of long-term interruptions in water supply, water supply companies should mainly continue replacing gray cast iron pipes with thermoplastic materials. Actions taken to increase the safety of drinking water supply meet the current standards for the safety of drinking water, developed by the World Health Organization and the European Union.

Camelina is a low input crop than can be cultivated in rotation with cereals to provide vegetable oil suitable for bioenergy production, industrial applications and even as source of food for livestock. At large scale farming, camelina seeds are currently harvested using a combine harvester, equipped with a cereal header, but the literature still lacks the knowledge of the performance of the machine, the harvesting cost and the related loss of seeds. The present study aims to fulfill that gap by reporting the results obtained from an ad hoc harvest field test. Camelina seed yield was 0.95 Mg ha−1 which accounted for the 18.60% of the total above ground biomass. Theoretical field capacity, effective field capacity and field efficiency were 3.38 ha h−1, 3.17 ha h−1 and 93.7% respectively, albeit the seed loss was 80.1 kg ha−1 FM (7.82% w/w of the potential seed yield). The presence of material other than grain was rather high, 31.77% w/w, which implies a second step of cleaning to avoid... [more]

In order to estimate the radiological characteristics of disused dry storage systems for spent nuclear fuel, a stepwise framework to calculate neutron sources (ORIGEN-ARP), incident neutron flux and reaction rate (MCNPX), effective cross-section (hand calculation), and residual activity (ORIGEN-2) was established. Applicability of the framework was demonstrated by comparing the residual activity of a commercialized storage system, HI-STORM 100, listed in the safety analysis report and calculated in this study. For a reference case assuming an impurity-free storage system, the modified effective cross-sections were theoretically interpreted and the need for managing disused components as a radioactive waste for at least four years was demonstrated. Sensitivity analyses showed that the higher burnup induces the higher residual radioactivity, and the impurity 59Co may extend the minimum decay-in-storage period up to 51 years within the reported range of 59Co content in stainless steel. Th... [more]

Hydrogen has attracted global attention as a clean secondary energy source and has numerous possible applications, including fuel for vehicles. To store the hydrogen effectively, ammonia is considered promising due to high hydrogen density, stability, and total energy efficiency. Adopting ammonia as a fuel in vehicles requires a proper fuel tank design to fulfill the required volumetric content and safety standards, without neglecting the economic objectives. In general, a type-IV pressure vessel is utilized as a fuel tank because it is the lightest one, compared to other types of pressure vessel. This paper focuses on the effort to develop a lightweight type-IV ammonia pressure vessel designed for mobility vehicles. The material combination (liner and composite) and composite stacking sequence are analyzed for both burst and impact tests by using a finite element method. Two polymer materials of polyethylene terephthalate (PET) and polypropylene (PP) are evaluated as the liner conside... [more]

Interdigitated back contact (IBC) n-type silicon solar cells with a different front surface layer doping concentration were fabricated and studied and the influence of the front surface doping level was analyzed via simulation (PC1D). The IBC cells were processed by industrially feasible technologies including laser ablation and screen printing; photolithography was not used. A maximum efficiency of up to 20.88% was achieved at an optimal front surface field (FSF) peak doping concentration of 4.8 × 1019 cm−3 with a sheet resistance of approximately 95 Ω/square, corresponding to Jsc = 40.05 mA/cm2, Voc = 671 mV and a fill factor of 77.70%. The effects of the front surface doping level were studied in detail by analyzing parameters related to carrier transmission mechanisms such as minority carrier concentration, minority carrier lifetime and the saturation current density of the FSF (J0e). The influence of the front surface recombination velocity (FSRV) on the performance of IBC solar c... [more]

The conversion of lignocellulosic biomass (LB) to sugar is an intricate process which is the costliest part of the biomass conversion process. Even though acid/enzyme catalysts are usually being used for LB hydrolysis, enzyme immobilization has been recognized as a potential strategy nowadays. The use of nanobiocatalysts increases hydrolytic efficiency and enzyme stability. Furthermore, biocatalyst/enzyme immobilization on magnetic nanoparticles enables easy recovery and reuse of enzymes. Hence, the exploitation of nanobiocatalysts for LB to biofuel conversion will aid in developing a lucrative and sustainable approach. With this perspective, the effects of nanobiocatalysts on LB to biofuel production were reviewed here. Several traits, such as switching the chemical processes using nanomaterials, enzyme immobilization on nanoparticles for higher reaction rates, recycling ability and toxicity effects on microbial cells, were highlighted in this review. Current developments and viabilit... [more]