This article reports on an experiment that aimed to investigate the effects of digestate and cosubstrate input with varying biochar concentrations on methane production in anaerobic digestion processes. The findings revealed distinct trends in methane production among the substrates. Further investigations were conducted to evaluate the effects of different types of biochars on biomethane production from raw cattle manure digestate. Four conditions were tested: one raw digestate condition and three digestate conditions containing 1% of a different biochar type to one another. BC1 (PEFC-certified spruce BC) and BC2 (oak wood BC) showed promising results in enhancing biomethane production. About 884.23 NmL of methane was produced, with a yield and productivity of 22.80 NmL.g−1 and 1.62 NmL.g−1.day−1 with BC1. However, BC3 (cow and chicken manure digestate BC) demonstrated lower biomethane production compared to raw digestate. Additionally, the study explored the effects of adding reagent... [more]

Powder bed fusion (PBF), a subset of additive manufacturing methods, is well known for its promise in the production of fully functional artefacts with high densities. The quality of the powder bed, commonly referred to as powder spreading, is a crucial determinant of the final quality of the produced artefact in the PBF process. Therefore, it is critical that we examine the factors that impact the powder spreading, notably the powder bed quality. This study utilised a newly developed testing apparatus, designed specifically for examining the quality of powder beds. The objective was to analyse the influence of various factors, including the recoater shape, recoater gap size, and the different powder flow properties, on the powder bed relative packing fraction. Additionally, the study aimed to assess the variation in the particle size and shape across the build plate. The results indicated that all of the variables examined had an impact on the relative packing fraction, as well as the... [more]

There are various organic compounds that can be utilized in the organic Rankine cycle as working fluids. The selection of a suitable working fluid is complicated due to the large number of options and factors affecting the choice, such as thermodynamic properties, environmental impact, cost, etc. This study evaluates seven different pure organic compounds and twenty-one of their binary zeotropic mixtures as potential working fluids for the organic Rankine cycle powered by a heat source at 200 °C. The pure organic fluids show higher exergy efficiency, higher specific net power output, and lower heat exchange area requirements compared to the binary mixtures. Among the pure fluids, RE347mcc performs the best in terms of exergy efficiency, followed by neopentane, isopentane, and pentane. Cyclopentane exhibits the highest power production capacity per unit mass flow rate of the working fluid. Two mixtures, pentane/Novec 649 and cyclopentane/Novec 649, showed significantly higher exergy eff... [more]

A review of desiccant dehumidification technologies for improving air quality is presented, mainly focusing on alternatives for air conditioning systems for minimizing Sick Building Syndrome. The principles and types of desiccant wheels, as well as the existing selection software for these types of equipment, were reviewed and comparatively evaluated. The study focused on the Brazilian context; thus, information about this country’s air conditioning systems and laws were evaluated. Possible applications of desiccant wheels, such as their integration into cooling cycles and the sensible heat wheel, were also analyzed. Finally, several examples of commercial desiccant wheel selection software that are useful in many situations were evaluated. Nevertheless, it was evidenced that the available software could not perform an operation analysis for only a specific period. Therefore, creating computational tools to select desiccant wheels is essential when considering the data from the differe... [more]

The process safety management (PSM) system was introduced in South Korea in 1996, wherein a company voluntarily organizes and manages a chemical accident prevention system, which contributes to reducing chemical accidents. However, large- and small-scale chemical accidents occur frequently. This trend necessitates analysis and improvement of the PSM systems. This study aimed to analyze the correlation between major industrial accidents, their main causes, the status of accidents by company size and industry, and the PSM evaluation grade through an analysis of 130 accidents that occurred in the past 17 years (2005−2021). The results showed that small- and medium-sized enterprises (SMEs) with fewer than 100 employees accounted for 36% of all accidents, indicating a higher occurrence rate than large companies. Additionally, the proportion of companies with inadequate PSM levels, rated as M-grade (M+, and M−), were 67.0%, suggesting a high probability of major industrial accidents. The res... [more]

Underground reservoir water storage technology has become one important way to achieve efficient coal mining and water resource protection in the western mining areas of China, and the width of coal pillar dams is an important factor affecting the safe operation of underground reservoirs. In order to study the limitations on the reasonable size of a coal pillar dam, Daliuta Mine was selected as the engineering background and a theoretical formula for the reasonable width of a coal pillar dam was proposed. By combining theoretical analysis with numerical simulation analysis, the main influencing factors of the coal pillar dam were compared and analyzed. The research results indicated that changes in the mining height and coal parameters can cause a sharp change in the width of the plastic zone of the dam body. Then, mine water will have an impact on the width of the plastic zone and the width of the elastic core. Moreover, when the width of the coal pillar is smaller than the theoretica... [more]

The growing importance of the membrane-based air separation processes results in an increasing demand for suitable polymeric membrane structures. This has spurred the interest in designing polymer structures for O2/N2 separation by employing a systematic approach. In this work, a computer-aided molecular design (CAMD)-based framework was developed to identify promising structures of polymers that can be used for air separation. To incorporate constraints in CAMD, the rough set-based machine learning (RSML) method was implemented to establish predictive models for the physical and transport properties of polymer owing to its interpretability. The deterministic rules generated from RSML would be interpreted scientifically reflecting the structure−property relationship to ensure that the molecules generated were feasible according to a scientific point of view. The most prominent rules selected were then integrated as constraints in CAMD. The relevant properties in this framework comprise... [more]

This study investigates the efficiency of a biogas-powered cooling system through the utilization of energy and exergy calculations. Biogas, which can be generated and stored in small-scale plants as needed, serves as a viable fuel source for absorption cooling systems. The present research focuses on the biogas consumption of a triple-effect absorption cooling system specifically designed to supply a fixed cooling load of 100 kW under varying operational conditions. This study highlights the coefficient of performance and exergetic coefficient of performance values of the system, along with the exergy destruction rates of its individual components, at the optimal temperatures of operation. Furthermore, to determine necessary biogas consumption, this study explores the establishment of dedicated farms for various animal species, ensuring an adequate number of animals for biogas production. The findings reveal a coefficient of performance of 1.78 and an exergetic coefficient of performa... [more]

A similarity criterion suitable for studying the vibration characteristics of converter transformers is proposed based on comprehensive consideration of geometric dimensions, electric field, magnetic field, force field, sound field, and coupling field interface interactions. By comparing the magnetic field, stress, displacement, sound field distribution, and vibration characteristics of the scale model of the converter transformer with the initial model, the reliability of the similarity criterion was determined. Based on the vibration similarity criterion of the converter transformer, a prototype of the proportional model was designed and manufactured, and vibration signals under no-load and load conditions were tested. These signals correspond to the vibration signals of the iron core and winding in the finite element model, respectively. Through comparative analysis, the reliability of the prototype and the vibration similarity model of the converter transformer has been proven, whi... [more]

In order to address the issue of a solar utilization system with low efficiency, this paper designs a new solar conversion system based on photovoltaic concentration and spectral splitting. The system concentrates sunlight through a Fresnel lens and uses a hollow concave cavity to evenly distribute the incident energy flow. The spectral splitting medium separates the useful irradiance for the PV cell from those wavelengths that are more suited to heat generation. By considering the available wavelength of photovoltaic cells, the GaAs cell and a ZnO nanofluid were selected for this paper. It was found that installing the hollow concave cavity improved the spot uniformity of the PV cell surface by 17%. The output efficiency of the system under various circumstances was analyzed. The results show that at a concentration ratio of 50 and a light intensity of 1000 W/m2, photoelectric conversion efficiency increased by 0.81%. When compared to direct concentration, the photoelectric conversion... [more]

Refractive index and density matching are essential for optical measurements of neutrally buoyant liquid−liquid flows. In this study, we proposed a design of experiments (DoE) to develop refractive index and density matching systems, including objective setting, candidates screening, sampling and fitting, and a detailed matching process. Candidates screening criteria based on the density and refractive index ranges of the aqueous and organic phases were used. Using the DoE, we proposed a system with a ternary aqueous phase potassium thiocyanate (KSCN)/ammonium thiocyanate (NH4SCN) solution and m-dichlorobenzene/tripropionin solution as the organic phase to achieve the tuning of the RI and density simultaneously. Empirical correlations of the refractive index and density with respect to the concentration and temperature for the three mixtures were obtained by combining Latin hypercube sampling with binary polynomial fitting. Correlations were validated with existing data in the literatu... [more]

Liability to prevent the consequences of an unhealthy situation due to accumulating toxic and hazardous emissions caused by open dumping of municipal solid waste with increasing urbanization has necessitated a renewed thinking on waste disposal. Grate-fired incineration systems were adopted by urban management in the past and present, but with criticism due to the formation of airborne emissions. Improved combustion methods like fluidized beds are now propagated because of current requirements like efficient energy recovery potential, stricter emission norms, adaptability with urban growth, adaptability to co-firing with other waste like biomass, edible oil wastes or industrial effluent, and integration with conventional energy generation. Such a comprehensive and futuristic approach is more sustainable for the community. A multi-criteria decision-making tool is used to identify the best technology option between grate combustion and fluidized bed combustion for disposing and energy re... [more]

On a cold single-phase test stand, the effect of central air on the exit flow field of Babcock, Germany, burner was investigated. Industrial measurements were taken for a 700 MW wall-fired pulverized-coal utility boiler with above burners. Gas temperature, gas composition and concentration in the burner area were measured at 444 MW, 522 MW and 645 MW loads, respectively. Only when the central air mass flow was zero did a center reflux zone exist in the burner outlet area. The steady combustion of faulty coal was aided by early mixing of primary and secondary air, which was made possible by the decreased central air mass flow. At all different loads, the pulverized coal in center region took a long distance to ignite. The temperature in center steadily dropped as central air mass flow decreased, while the temperature in secondary air region gradually rose. Within 1.5 m from the primary air duct outlet, the highest CO concentration was 25 ppm and the highest O2 concentration was close to... [more]

Denim production wastewater is an industrial wastewater with a high organic pollutant content. The aim of this study was to improve a cost-effective method via solar panel integration to the photo Fenton process (PFP) and photo electrochemical Fenton process (PEFP) for removing high chemical oxygen demand (COD) from denim production wastewater. To determine process parameter values, the double criterial optimization option was used. The results that maximized the COD removal efficiency and minimized the operating cost of two oxidation processes were determined by response surface methodology (RSM). Optimum operation conditions for the PFP process were 3.18 initial pH, 2.3 g/L Fe2+ concentration, and 27 g/L H2O2 concentration while they were 3.00 initial pH, 27.06 A/m2 current density, and 28.16 g/L H2O2 concentration for PEFP. At the optimum conditions, COD and the total organic carbon (TOC) removal efficiency of PFP were 85% and 61%, respectively. They were determined as 90% and 73% i... [more]

The Anaerobic Digestion Model 1 is the quasi-industry standard for modelling anaerobic digestion, and it has seen several new implementations in recent years. It is assumed that these implementations would give the same results; however, a thorough comparison of these implementations has never been reported. This paper considers four different implementations of ADM1: one in Julia, one in Java, and two in Python. The Julia code is a de novo implementation of the ODE formulation of ADM1 that is reported here for the first time. The existing Java and Python codes implement the more common DAE formulation. Therefore, this paper also examines how DAE implementations compare to ODE implementations in terms of computational speed as well as solutions returned. As expected, the ODE and DAE forms both return comparable solutions. However, contrary to popular belief, the Julia ODE implementation is faster than the DAE implementations, namely by one to three orders of magnitude of compute time,... [more]

This work reports on the development of a real-time vehicle sensor network (VSN) system and infrastructure devised to monitor particulate matter (PM) in urban areas within a participatory paradigm. The approach is based on the use of multiple vehicles where sensors, acquisition and transmission devices are installed. PM values are measured and transmitted using standard mobile phone networks. Given the large number of acquisition platforms needed in crowdsensing, sensors need to be low-cost (LCS). This sets limitations in the precision and accuracy of measurements that can be mitigated using statistical methods on redundant data. Once data are received, they are automatically quality controlled, processed and mapped geographically to produce easy-to-understand visualizations that are made available in almost real time through a dedicated web portal. There, end users can access current and historic data and data products. The system has been operational since 2021 and has collected over... [more]

Due to the success of the first edition of the Special Issue “Industrial Chemistry Reactions: Kinetics, Mass Transfer and Industrial Reactor Design” in terms of both the quantity and quality of the published papers, we thought it would be prudent to announce a second edition [...]

Microchannel cooling technology is an effective method to solve local thermal stacking. In this paper, four innovative microchannels with bionic fish-shaped rib arrangements (CM-O, CM-R, CM-H, and CM-G) are designed by imitating geese and fish clusters. The heat transfer and flow characteristics of the microchannels are simulated numerically at different Reynold’s numbers (Re = 200 − 1600). The liquid water temperature and flow field in the four innovative microchannels with bionic ribs are analyzed. The results show that the ribs’ arrangement has an influence on the thermal performance of microchannels. Compared to the smooth microchannel (CM), the of the Nu microchannels with the bionic fish-shaped ribs increases by 33.00−53.26% while the fave increases by 28.63−34.93% at Re = 1200. The vortices around the ribs are clearly observed which improves the temperature gradient. The performance evaluation criterion (PEC) of CM-H is higher than that of the others. This indicates that the rib... [more]

Solar cells, liquid crystal displays (LCDs) and light-emitting diodes (LEDs) have become more and more important in recent decades. Crucial components of such electronic devices include rare metals (e.g., indium and gallium), which are only available in limited quantities. In order to meet their rising demand in the coming years, recycling processes, especially those that enable selective recovery of the individual components, are steadily gaining in importance. One conceivable method is particle-loaded solvent extraction followed by mechanical processing. Therefore, we first investigated the possibility of recovering individual particle fractions from a multicomponent mixture on the basis of the surface properties. Both UV−Vis spectroscopy and small-angle X-ray scattering (WAXS) were used for evaluation. The conducted experiments showed, among other things, that the indium oxide content increased from 50% to 99% in a binary system and from 33% to 94% in a ternary compound. In addition... [more]

In order to address the challenges associated with free lipase in organic solvents, including aggregation, poor stability, and low catalytic efficiency, this study developed two types of poly(o-phenylenediamine) microspheres (solid and hollow) as supports for immobilizing lipase. The immobilization process utilized an adsorption method, with the poly(o-phenylenediamine) hollow microspheres being identified as the optimal support in a 2:5 enzyme-to-support ratio. On this basis, the lipase was immobilized by the covalent binding method. The immobilization conditions consisted of treating the support with 2% glutaraldehyde and immobilization at 40 °C for 2 h in pH 7.0 buffer. The specific activity of the immobilized enzyme was 5.3 times higher than that of the free enzyme. Covalent-binding immobilized lipase was also used for the preparation of citronellyl acetate by transesterification reaction, and, in optimized reaction conditions where the amount of immobilized enzyme was 0.1 g/mL, th... [more]

This study aimed to evaluate the potential of utilizing aerated concrete (AC) and clay bricks (CB) sourced from construction and demotion waste (CDW) as low-cost adsorbents for the removal of Pb2+ from aqueous solutions. The effects of various parameters, including particle size, solution pH, contact time, adsorbent dosage, and initial Pb2+ concentration, were analyzed through batch experiments. The results indicated that AC performed more efficiently in removing lead ions than CB under all the tested conditions. The highest removal efficiency of Pb2+ with AC was 99.0%, which was achieved at a pH of 5.0, contact time of 1 h, an adsorbent dosage of 5 g/L, and an initial Pb2+ concentration of 100 mg/L. The maximum adsorption capacities of AC and CB were 201.6 mg/g and 56.3 mg/g, respectively. The adsorption isotherm data of the adsorbents were successfully modeled using both the Langmuir and Freundlich models. The removal of lead ions from aqueous solutions by both adsorbents is primaril... [more]

The reduced solubility of inorganic salts in supercritical water has a significant impact on the stable operation of desalination facilities as it may lead to surface fouling due to salt deposition. In this study, the solubility of Na2SO4 was experimentally determined to be 0.04−15.34 mmol/kg water at 23−25 MPa and 390−420 °C. To investigate the precipitation behavior of Na2SO4 in supercritical water, a reactor with a heating bar was designed and the deposition effect of salt on the superheated surface in an autoclave was tested at a temperature of 390 °C and a pressure of 23 MPa. Then, the deposition mechanism of salt in the autoclave was analyzed and the temperature field in the reactor was simulated using CFD commercial software. The experimental results showed that Na2SO4 was present on both the heating rod and the bottom of the autoclave with a loose salt layer. The simulation results indicated that the temperature near the heating rod was significantly higher than the bulk fluid... [more]

Conveyor belts are widely used in ore transportation in large-scale mines for their long transportation range, high safety, and strong economic applicability. Coal mine belt conveyors are not only traditional, simple mechanical conveying devices but also automatic control system operating devices that integrate safety, stability, and low power consumption. In the process of coal mining, a conveyor belt control system also needs to be closely integrated with modern industrial systems and information systems, which greatly improves its work efficiency. The purpose of this article is to improve the methods for designing automatic control systems for electric motors in order to obtain mechanical characteristics close to a constant power line, which would ensure the reliable operation of belt conveyors. An automatic control system was designed based on the controller Siemens S7-1200; then, a mathematical model of an automated electric drive was developed. Based on the mathematical model, a... [more]

Cranioplasty or cranial reconstruction is always a challenging procedure even for experienced surgeons. In this study, two different design techniques for customized cranial prostheses are assessed for cranial reconstruction. Mirror reconstruction is one of the commonly used reconstruction techniques that fails when cranial defects cross the midline of symmetry. Hence, there is a need for a design technique for the reconstruction of cranial defects irrespective of their location on the symmetrical plane. The anatomical reconstruction technique demonstrates its applicability for a wide spectrum of complex skull defects irrespective of the defective position in the anatomical structure. The paper outlines a methodological procedure involving a multi-disciplinary approach involving physicians and engineers in the design and reconstruction of customized cranial implants for asymmetrical skull defects. The proposed methodology is based on five foundation pillars including the multi-discipli... [more]

When designing a new type of power plants operating on pulsed detonations of gaseous or liquid fuels, the concept of fast deflagration-to-detonation transition (FDDT) is used. According to the concept, a flame arising from a weak ignition source must accelerate so fast as to form an intense shock wave at a minimum distance from the ignition source so that the intensity of the shock wave is sufficient for fast shock-to-detonation transition by some additional arrangements. Hence, the FDDT concept implies the use of special means for flame acceleration and shock wave amplification. In this work, we study the FDDT using a pulsed detonation tube comprising a Shchelkin spiral and a helical tube section with ten coils as the means for flame acceleration and shock amplification (focusing), respectively. To attain the FDDT at the shortest distances for fuels of significantly different detonability, the diameter of the pulsed detonation tube is taken close to the limiting diameter of detonation... [more]