The paper describes an installation for the degradative depolymerization of polyolefin materials obtained from wastes, hereinafter also referred to as depolymerization for simplicity. The plant, on an industrial scale, is one of the few operating in Poland. However, it is one of the most modern plants in this industry. Design solutions, construction of particular technological lines, compliance with national and EU regulations and the high level of process safety were described in this paper as well as compared to other plants of this type in Poland. Different solutions were presented in drawings and photos of the plant and in fragmentary technological diagrams. The types of waste and the methods of their processing by the plant were also characterized in accordance with the applicable regulations. The waste throughput is from 2000 to 4000 kg/h, while the efficiency of the depolymerization installation itself is 1500 kg/h. The industrial-scale depolymerization process is carried out in... [more]

Methanol production via carbon dioxide (CO2) hydrogenation is a green chemical process, which can reduce CO2 emission. The operating conditions for minimum methanol production cost of three configurations were investigated in this work. An artificial neural network with Latin hypercube sampling technique was applied to construct model-represented methanol production. Price sensitivity was performed to study the impacts of the raw materials price on methanol production cost. Price sensitivity results showed that the hydrogen price has a large impact on the methanol production cost. In mathematical modeling using feedforward artificial neural networks, four different numbers of nodes were used to train artificial neural networks. The artificial neural network with eight numbers of nodes showed the most suitable configuration, which yielded the lowest percent error between the actual and predicted methanol production cost. The optimization results showed that the recommended process desig... [more]

This paper presents the possibility of using Gallium Nitride (GaN) high-electron-mobility transistors (HEMTs) instead of the conventional silicon metal oxide semiconductor field effect transistor (MOSFET) to implement a high-frequency intermediate bus converter (IBC) as part of a typical distributed power architecture used in a space power application. The results show that processing the power at greater frequencies is possible with a reduction in mass and without impacting the system efficiency. The proposed solution was experimentally validated by the implementation of a 1 MHz zero-voltage and zero-current switching (ZVZCS) current-fed half-bridge converter with synchronous rectification compared with the same converter using silicon as the standard technology on power switches and working at 100 kHz. In conclusion, the replacement of silicon (Si) transistors by GaN HEMTs is feasible, and GaN HEMTs are promising next-generation devices in the power electronics field and can coexist... [more]

Biological metal leaching is a technology used in the mining and biohydrometallurgy industries where microorganisms mediate the dissolution of metals and semi-metals from mineral ores and concentrates. The technology also has great potential for various types of metal-rich waste. In this study, bioleaching was used for sludge from water treatment. In addition to checking the applicability of the process to such a substrate, the influence of experimental conditions on the effectiveness of bioleaching of metals with sludge from water treatment was also determined, including sample acidification, addition of elemental sulfur, incubation temperature, and Acidithiobacillus thiooxidans-isolated strain. The measurement of metal concentration and, on this basis, the determination of bioleaching efficiency, as well as pH and oxygen redox potential (ORP), was carried out during the experiment at the following time intervals: 3, 6, 9, 12 days. After the experiment was completed, a mass balance wa... [more]

As third-generation semiconductors become commercial, SiC semiconductors are gradually becoming more widely used in LLC resonant converters. The efficiency of the LLC resonant converter is improved by employing soft switching. However, when designing LLC resonant converters, semiconductors are usually regarded as ideal devices, and their turn-on and turn-off times are neglected. Furthermore, the method of designing the dead time relies on engineering experience and lacks precise theoretical foundations. In order to overcome the shortcomings of the current empirical method and to improve the generality and practicality of the dead time design method, a novel method for calculating the dead time of full-bridge LLC converters is proposed through theoretical research based on the operating principle of full-bridge LLC converters and the conditions for implementing soft switching. The method takes into account the switching characteristics of semiconductors and the on-state delay time of th... [more]

The interference-fit size has a significant effect on the riveted lap joints of CFRP/Al alloy laminates. The requirements for the interference-fit size are different because of the strengthening of heterogeneous materials. However, in the riveting process of CFRP/Al alloys, the heterogeneous laminates lead to poor structural strength because of the different interference-fit size requirements. Therefore, differently assembled riveting molds are designed to acquire a novel interference-fit size, and the tensile test is adopted to evaluate their tensile properties. In addition, the fracture failure of CFRP/Al alloy laminate riveted lap joints is observed with an ultra-depth-of-field microscope. Finally, the best assembly type is identified as the trapezoid riveting mold combined with an arc riveting die, and the sidewall intersection angle of the trapezoid riveting mold is 66°, which could achieve a suitable interference-fit size and a better mechanical performance.

One important application of polymer/graphene nanocomposites is in membrane technology. In this context, promising polymer/graphene nanocomposites have been developed and applied in the production of high-performance membranes. This review basically highlights the designs, properties, and use of polymer/graphene nanocomposite membranes in the field of gas separation and purification. Various polymer matrices (polysulfone, poly(dimethylsiloxane), poly(methyl methacrylate), polyimide, etc.), have been reinforced with graphene to develop nanocomposite membranes. Various facile strategies, such as solution casting, phase separation, infiltration, self-assembly, etc., have been employed in the design of gas separation polymer/graphene nanocomposite membranes. The inclusion of graphene in polymeric membranes affects their morphology, physical properties, gas permeability, selectivity, and separation processes. Furthermore, the final membrane properties are affected by the nanofiller content,... [more]

The challenges posed by elevated rock hardness, deficient drillability, excessive friction torque, and significant underpressure in extended−reach horizontal wells are the primary factors that contribute to low ROP (Rate of Penetration) and limited horizontal reach during the drilling operation. Reducing drag and friction is one of the primary methods of addressing the aforementioned challenges. To augment the pulse output characteristics of the oscillating jet and bolster the energy of the hydrodynamic impact load, we developed and designed a multi−source impact oscillation speed−increasing tool coupled with blade rotation disturbance and multi−order oscillation cavity self−excitation. We utilized fluid dynamics software to model and conduct numerical analysis on the multi−source pulsed jet generator. Furthermore, we constructed a prototype and subjected it to testing. This paper examines the impact of dimensionless structural parameters on the pressure output characteristics of the m... [more]

Graphene is an important nanocarbon nanofiller for polymeric matrices. The polymer−graphene nanocomposites, obtained through facile fabrication methods, possess significant electrical−thermal−mechanical and physical properties for technical purposes. To overcome challenges of polymer−graphene nanocomposite processing and high performance, advanced fabrication strategies have been applied to design the next-generation materials−devices. This revolutionary review basically offers a fundamental sketch of graphene, polymer−graphene nanocomposite and three-dimensional (3D) and four-dimensional (4D) printing techniques. The main focus of the article is to portray the impact of 3D and 4D printing techniques in the field of polymer−graphene nanocomposites. Polymeric matrices, such as polyamide, polycaprolactone, polyethylene, poly(lactic acid), etc. with graphene, have been processed using 3D or 4D printing technologies. The 3D and 4D printing employ various cutting-edge processes and offer en... [more]

Olive cake, the solid byproduct of three-phase centrifugation olive oil production, has a high organic and polyphenol content, rendering it an environmental threat when landfilled as well as limiting its animal feed potential. This residue can be a good candidate for biomethane production due to its rich polysaccharide content (pectin, hemicellulose, and cellulose). Two strategies were compared to maximize biomethane production: destoning (i.e., removal of the seed fragments via mechanical means) and enzymatic pretreatment of the pulp. After 30 days of batch anaerobic digestion at 35 °C, both enzymatically pretreated and destoned olive cakes produced similar amounts of methane (~295 mL CH4/g volatile solids (VS)), 42% more than the control. A comparison of olive cake’s biomethane yields with a broad range of agricultural residues in the literature demonstrated its suitability for biomethane production. Additionally, the digestate recovered from the anaerobic digestion of olive cake had... [more]

In this study, an industrial biomass-drying wastewater condensate containing > 3200 mg/L NH4+ and >8900 mg/L CH3COO− was treated in ion-exchange columns for the recovery of NH4+. Two commercial resins (CS12GC and CS16GC) were studied on laboratory and pilot scales. CS16GC outperformed CS12GC by achieving better separation at the condensate temperature (60 °C), which was energy-efficient regarding NH4+ removal. K3PO4 was used for regeneration to produce a liquid compound fertilizer containing nutrient elements (N, K, and P) as a byproduct. The N/K ratio in the byproduct was found to be adjustable by varying the operating parameters. Regeneration with 2 mol/L K3PO4 gave a higher regeneration efficiency (97.67% at 3 BV and ~100% at 4 BV). The stability tests performed on a laboratory scale showed that the cyclic runs of the column separation process were steady and repeatable. Based on the outcomes of the laboratory-scale tests, the pilot-scale tests applied a loading volume of 7 BV. The... [more]

The purpose of this work is to develop two types of dietary supplements for celiac (energy-rich and fiber-rich bars) as well as to optimize the formulations of bars made from puffed and non-puffed cereals. To optimize the combination of components, a mixture design was created. Based on sensory evaluation, optimal bars were selected, which were then evaluated in terms of biochemical properties, color and antioxidant properties. The main results indicate that the combination of 37.5 g of cereals, 22.5 g of seeds, and 40 g of binder is optimal for the energy bars with non-puffed cereals, followed by 54.57 g of cereals, 10.43 g of seeds, and 35 g of a binder for fiber-rich bars with non-puffed cereals. In contrast, the optimal recipe for energy bars with puffed cereals consisted of 35.42 g of cereals, 20.07 g of seeds, and 44.51 g of binder, and for fiber-rich bars with puffed cereals, it consisted of 50 g of cereals, 15 g of seeds, and 35 g. The biochemical composition indicates that fib... [more]

The influence of process water recycling during the Supercritical Water Gasification (SCWG) of dry biomasses was investigated. Dry biomass has to be diluted with water to a dry matter content of approximately 10 wt.% to gasify it in the process of supercritical water gasification. The treatment of wastewater in the SCWG process is cost intensive due to organic contaminants; therefore, the recycling of the process effluent is attractive. Salt separation is needed to avoid accumulation of salts in the effluents, since salts enhance corrosion rates and might cause blocking of the flow when the effluent is recycled. The grass Reed Canary Grass and grapevines were gasified. The recycling of the process effluent did not influence the composition of the product gas. In both cases the carbon efficiency decreased by 4% when wastewater was used to dilute the biomass. An increase in organic carbon and potassium in the reactor effluent was observed after gasification of the biomass with recycled p... [more]

In this study, we carried out a para-xylene crystallization experiment at constant temperature and concentration levels. Throughout the process, the kinetics of nucleation, growth, breakage, and aggregation of para-xylene particles were measured and built using a morphological approach. An additional a three-stage continuous suspension crystallization separation experiment was carried out, the process for which was simulated using the population balance model based on correlated kinetic equations. The population balance equation was solved using an extended moment of classes algorithm, and the solving process was implemented in MATLAB. In this case, the predicted particle size distribution of the products matched well with the experiment. In order to provide references for the optimization of the industrial para-xylene crystallization process, a three-stage suspension crystallization separation experiment was designed and conducted, in which each crystallizer had a distinct operating t... [more]

Deep application of liquid fertilizer is a technique that applies liquid fertilizer deep near the root system of crops, which has many advantages such as high fertilizer utilization rate and low environmental pollution. However, high power and high specific energy consumption caused by soil-engaging components in liquid fertilizer deep application make it difficult to popularize in northeast China. The claw-toe structure of burrowing animals has the characteristics of low resistance and low friction, which has been the focus of many scholars’ research on soil-engaging components. The claw-toe structure of the badger, a widely distributed burrowing animal in northeast China, has good characteristics of low power and low specific energy consumption. Therefore, in this research, a bionic liquid fertilizer deep application spray needle was designed, based on the claw-toe structure of the badger, to improve the operating performance of liquid fertilizer deep application. In this research, t... [more]

Hyperloop technology is a transport mode designed to move passengers anywhere in the world, using electric propulsion to carry passengers through a vacuum/near-vacuum tube for a maximum speed of 1200 km/h. Given this, governments, engineers, researchers, and billionaires have been racing over the past years to obtain the first operational system in the world off the ground and bring it from concept to reality. The paper aimed to maximize the capacity of the Hyperloop’s capsule and identify a suitable design of Hyperloop technology based on the different capacities and speeds of the capsules as well as the assumptions of the initial annual demand. Additionally, significant attention will be paid to the interior design of the capsules in which people travel to make the journey more comfortable and enjoyable. The design will be conducted in AutoCAD and Autodesk Revit models based on the allocation of different components such as capacity, compressor fan, batteries, compressor motor, etc.... [more]

The effect of temperature was studied on the synthesis of fatty acid alkyl esters by means of transesterification of waste beef tallow using ethanol and, iso-butanol and 1-butanol at supercritical conditions. These alcohols are proposed for the synthesis of biodiesel in order to improve the cold flow properties of alkyl esters. Alcohol−beef tallow mixtures were fed to a high-pressure high-temperature autoclave at a constant molar ratio of 45:1. Reactions were carried out in the ranges of 310−390 °C and 310−420 °C for ethanol and iso-butanol, respectively; meanwhile, synthesis using 1-butanol was assessed only at 360 °C. After separation of fatty acid alkyl esters, these samples were characterized by nuclear magnetic resonance (NMR) and gas chromatography coupled to mass spectrometry (GC-MS) to quantify yields, chemical composition, and molecular weight. Results indicated that yields enhanced as temperature increased; the maximum yields for fatty acid ethyl esters (FAEEs) were attained... [more]

The design parameters of a mixing system have a major impact on the quality of the final product. Therefore, identifying the optimum parameters of mixing systems is highly relevant to various industrial processes dealing with particulate flows. However, the studies on the influences of the mixer’s design features are still insufficient. In this study, the Discrete Element Method (DEM) is used to examine the impact of paddle angle, width, and gap on the mixing performance of a twin paddle blender. The mixing performance and particle flow are assessed using the relative standard deviation (RSD) mixing index, velocity field, diffusivity coefficient, granular temperature, the force acting on particles, and the mixer’s power consumption. The mixing performance is highest for a paddle angle of 0° at the cost of the highest forces acting on particles. The paddle width is indicated as a critical factor for achieving better mixing quality. In contrast, the powder mixing efficiency and the mixer... [more]

The technology for reproducing orchids in vitro has had to evolve due to the demand for these plants and the high cost of the biotechnology used due to the agar, the gelling agent. Consequently, research has tended to search for natural substitutes for agar. Our work describes the use of pectin and mucilage hydrocolloids extracted from the local waste matter of two species of Opuntia (O. ficus-indica and O. robusta) to study as a gelling agent in vitro culture media for Cattleya sp. These hydrocolloids were obtained by alkaline hydrolysis. Subsequently, these were used in proportions of 0.8%, 0.6%, 0.4%, and 0.2% in combination with agar to study the gelation time, texture profile analysis (TPA), seed germination under light and dark conditions, and a phenological study, including orchid analyses of leaves and roots, root and leaf length, seedling height, and width of the best-designed treatment were studied. Our results demonstrate that the treatment composed of 0.4% O. ficus-indica p... [more]

Research in the field of industrial heritage regeneration suffers from high subjectivity and low reliability in design and evaluation. The study takes seven regeneration projects of the Kailuan family of industrial heritage as examples, designs four optimisation and improvement strategies and constructs an evaluation system containing four intermediate layers and 23 indicator layers based on the evaluation factor method to realise the evaluation of design solutions. The average evaluation value of the four intermediate layers was approximately 0.65, and the average evaluation value of the 23 evaluation indicators was approximately 0.68. The evaluation values of the four intermediate layers for the seven Kailuan projects showed that the evaluation of the park and the evaluation of the participants’ perceptions were roughly higher than the standard values, while the evaluation of the buildings and the evaluation of the environmental image had lower evaluation values. The correlations bet... [more]

Ammonia is a promising carbon-free energy vector, hydrogen carrier, and efficient means for long-time hydrogen storage. Power-to-ammonia-to-power concepts, powered exclusively by electricity from renewable sources, will leave the carbon economy behind and enter a truly renewable era. However, the fluctuating nature of renewables requires a good dynamic behavior of such concepts. Employing the software Aspen Plus Dynamics®, this paper investigates the dynamic behavior of a novel containerized power-to-ammonia solution to be tested at the University of Genova in 2023. Implementing a novel kinetic reaction model, the impacts of several deviations from the optimal values of the cycle parameters are investigated. The simulations provide practical guidance on how to best and safely operate the cycle. A total of ten scenarios were simulated, of which six are acceptable, two are desirable, and two should be avoided. However, all scenarios can be safely controlled by the control infrastructure.

Non-processed kaolin (flint kaolin) from a mine located in the Capim area (Amazon region, northern Brazil), usually considered as waste, was selected as a source of silicon and aluminum in the synthesis of SAPO-34. This is a molecular sieve and cationic exchanger chosen for tests focusing on the removal of methylene blue in aqueous solutions, which is a cationic dye widely used by textile industries in Brazil. The results revealed that the SAPO-34 has been successfully synthesized with typical cubic morphology, good crystallinity (>90%), and thermal stability (~998 °C). Although the oxidized Fe/Ti impurities contained in the flint kaolin affect the degree of crystallinity of the zeolitic product, its adsorptive properties are not significantly affected, which demonstrates the excellent adsorption results (pH = 11; % removal > 90%). It proved to be an adsorbent with considerable adsorption capacity (9.83 mg·g−1). The pH test confirmed the acidic surface characteristics (pH solution 2−4;... [more]

Energy performance of buildings is a worldwide increasing investigated field, due to ever more stringent energy standards aimed at reducing the buildings’ impact on the environment. The purpose of this paper is to assess the impact that occupant behavior and climate change have on the heating and cooling needs of residential buildings. With this aim, data of a questionnaire survey delivered in Southern Italy were used to obtain daily use profiles of natural ventilation, heating, and cooling, both in winter and in summer. Three climatic scenarios were investigated: The current scenario (2020), and two future scenarios (2050 and 2080). The CCWorldWeatherGen tool was used to create the weather files of future climate scenarios, and DesignBuilder was applied to conduct dynamic energy simulations. Firstly, the results obtained for 2020 demonstrated how the occupants’ preferences related to the use of natural ventilation, heating, and cooling systems (daily schedules and temperature setpoint... [more]

The food manufacturing sector is one of the most dominant consumers of energy across the globe. Food processing methods such as drying, baking, frying, malting, roasting, etc. rely heavily on the heat released from burning fossil fuels, mainly natural gas or propane. Less than half of this heat contributes to the actual processing of the product and the remaining is released to the surroundings as waste heat, primarily through exhaust gases at 150 to 250 °C. Recovering this waste heat can deliver significant fuel, cost and CO2 savings. However, selecting an appropriate sink for this waste heat is challenging due to the relatively low source temperature. This study investigates a novel application of gas-to-air low temperature waste heat recovery technology for a confectionary manufacturing process, through a range of experiments. The recovered heat is used to preheat a baking oven’s combustion air at inlet before it enters the fuel-air mixture. The investigated technology is compared w... [more]

A non-linear three-dimensional inverse shape design problem was investigated for a pipe type heat exchanger to estimate the design variables of continuous lateral ribs on internal Z-shape lateral fins for maximum thermal performance factor η. The design variables were considered as the positions, heights, and number of ribs while the physical properties of air were considered as a polynomial function of temperature; this makes the problem non-linear. The direct problem was solved using software package CFD-ACE+, and the Levenberg−Marquardt method (LMM) was utilized as the optimization tool because it has been proven to be a powerful algorithm for solving inverse problems. Z-shape lateral fins were found to be the best thermal performance among Z-shape, S-shape, and V-shape lateral fins. The objective of this study was to include continuous lateral ribs to Z-shape lateral fins to further improve η. Firstly, the numerical solutions of direct problem were solved using both polynomial and... [more]