Results in Engineering最新文献

The metal cutting industry faces challenges in machining hard materials due to high forces and temperatures. This paper introduces bubble-bursting atomization minimum quantity lubrication (BBA-MQL), a novel MQL technique that generates fine biodegradable oil mists for cooling and lubrication. Although the initial results of BBA-MQL are promising, there has not been a comprehensive investigation into its use in machining hard materials, specifically tool steels. Therefore, this study focused on the applicability of BBA-MQL in face milling of AISI P20 + Ni tool steel in comparison with dry cutting and conventional MQL using commercial and vegetable oil. The machining tests were performed at three cutting speeds (50, 80, and 110 m/min), fixed cutting depth (0.2 mm), and feed rate (0.15 mm/tooth). The performance is evaluated by measuring the cutting force, surface quality, cutting temperature, and tool wear. It was found that BBA-MQL decreased cutting force and surface roughness considerably, with the average reductions being 23.2 % and 49.8 % compared with the conventional minimum quantity lubrication. The highest cutting speed of 110 m/min was preferred for achieving the lowest roughness value and cutting force when milling tool steel P20 + Ni. Furthermore, BBA-MQL with castor oil proved more effective compared to conventional MQL in reducing cutting force, showing improved surface finish, reduced cutting temperature, and delayed tool wear.

Efficient thermal management is essential for designing compact and high-performance heat sinks and heat exchangers. This study addresses the challenge of optimizing heat transfer while minimizing pressure losses in systems exposed to concentrated heat flux by proposing a novel approach that employs both active and passive vortex generators. Specifically, a uniform magnetic field generated by permanent magnets and a bluff body are utilized within a microchannel containing a 2 vol% ferrofluid. Numerical simulations were performed across Reynolds numbers ranging from 100 to 500 and magnetic field intensities up to 0.5 T to evaluate the system's performance. The results demonstrate that the combination of magnetic fields and a bluff body induces vortex generation, alters velocity distribution, and enhances flow mixing, resulting in a 30 % increase in heat transfer efficiency and an 11 % reduction in pressure drop under optimal conditions. Although the introduction of barriers led to a 3 % rise in pressure drop, the uniform magnetic field effectively mitigated friction by reducing flow separation and limiting surface contact. These findings highlight the potential of this method for improving the design of advanced thermal management systems.

In the face of escalating global demands for sustainable practices within the construction and mining sectors, this paper investigates the transformative impact of automated load analysis technologies. Focused on bridging the gap between traditional operational methodologies and the forefront of automation technology, the study provides an in-depth examination of the integration of onboard weighing systems, the Internet of Things (IoT), and machine learning into mining operations. Through a series of detailed case studies, the research showcases how these technological innovations contribute to substantial improvements in operational efficiency, notably through enhanced load management, reduced fuel consumption, and optimized resource allocation, thereby fostering a decrease in the environmental footprint of mining activities. Furthermore, the paper addresses critical sustainability issues, including workforce transformation, stakeholder engagement, and the broader environmental implications of adopting automated technologies in mining processes. Concluding with strategic policy recommendations, the study advocates for widespread adoption of automated systems within the construction sector to achieve improved environmental and economic outcomes. By emphasizing a multidisciplinary approach, this research highlights the essential role of technological innovation in aligning mining operations with sustainable development goals, positioning automated load analysis as a pivotal strategy for advancing eco-efficiency in the construction and mining industries.

Due to a synergy effect, using dielectric barrier discharge (DBD) plasma technology combined with catalysts for CO₂ decomposition, a major contributor to global warming, is recognized as an effective approach to transforming CO₂ into valuable products such as CO, which is a crucial feedstock for chemical synthesis. Herein, HKUST-1 was synthesized using the hydrothermal method for CO₂ conversion in the DBD reactor. To enhance catalyst performance in the plasma region, HKUST-1 was treated with O₂ plasma to increase its specific surface area. Additionally, HKUST-1 was calcined at 300 °C to produce the CuO/Cu₂O catalyst. Since the recombination reaction in the CO₂ conversion is increased at higher temperatures, the reactor heat is removed using fan cooling and a water circulation system. In the presence of the HKUST-1 catalyst, the CO₂ conversion rate significantly increased by 132 %, 82 %, and 12 % in reactors operating without cooling, with fan cooling, and with water cooling circulation, respectively compared to the reactors without catalyst, at a flow rate of 50 ml/min and maximum input power. The catalysts have been characterized using a comprehensive suite of analytical techniques, including FTIR, XRD,TEM, SEM, EDS, and BET analysis. The BET analysis indicates that the specific surface area of HKUST-1 after O₂ plasma treatment is increased by 52 %, which causes an increasing conversion rate of up to 18 %. The CuO/Cu₂O catalyst demonstrated maximum CO₂ conversion of 21 % at an input power of 140 W and achieved energy efficiency of 8.6 % at 40 W. The presence of oxygen vacancies within this catalyst enhances the process of CO₂ decomposition.

Natural fiber-reinforced polymer matrix composites recently got great attention in biomedical applications due to their inherent characteristics such as biocompatibility, lightweight, and biodegradability. However, natural fiber composites suffer from poor mechanical properties and weak interfacial adhesion. It is well documented that the addition of nanofiller has improved the mechanical properties of different synthetic fibers such as glass and carbon composites. The main objective of this paper is to study nanofillers' effect on the mechanical properties of unidirectional false banana fibers reinforced polymer composites. The filler materials, crystalline nanocellulose fibrils, and crystalline nanosilica particles were extracted from sugarcane bagasse and its byproducts. The composite samples were fabricated by adding the nanofillers in unidirectional natural fibers arranged in four fiber orientations (0°, 0^o/90^o ±45^o, and quasi-isotropic), and their tensile, flexural, compression strength, thermal stability, and void content were measured following ASTM standards. The results revealed that adding nanofillers increased the tensile, flexural, and compressive strengths by 16 % (98.83 Mpa), 11 % (161.60 Mpa), and 23 % (114.62 Mpa), respectively. Similarly, at 0° orientation, the addition of nanoparticles enhances the tensile, bending, and compressive modulus by 30 % (15.43 Gpa), 12 % (13.52 Gpa), and 60 % (42.6 Gpa), respectively. On the other hand, the void content was reduced with the addition of nanofillers. The results also revealed that composites with crystalline nanosilica particle fillers had superior thermal stability compared to crystalline nanocellulose fibril fillers. The overall results of this research give the confidence that nano particle-filled natural fiber composites can be used for bio-based engineering applications, such as prosthetic sockets.

Drying is a fundamental process for preserving agricultural products, involving heat and mass exchanges. As a sustainable selection, researchers are focusing on solar dryers to improve drying efficiency, shorten drying times, and maintain product quality. Indirect type solar dryers (ITSD) have shown promise in post-harvest preservation. However, there is a lack of detailed investigation in their unique features, types, and performance-enhancement techniques. Thermal energy storage methods, which store excess energy for times when there is no solar irradiance, can improve the dependability of solar drying. Expensive experimental setups have led to the use of computer simulation techniques like computational fluid dynamics (CFD) to optimize drying conditions and dryer design while maintaining product quality. The review aims to provide an overview of different ITSD designs, techniques of thermal energy storage, and explore the use of CFD in analyzing heat and mass transfer phenomena in indirect solar drying systems. Additionally, this review study inspires researchers to explore the development of indirect solar dryers suitable for various drying environments, diverse product drying capacities, and different drying durations. Further research and development in these areas will continue to enhance the performance, energy efficiency, and scalability of indirect solar dryers, contributing to sustainable agriculture and energy conservation.

The morphology and composition of phosphorus in biomass wastes are key factors in determining its potential for utilization. However, the morphological distribution and evolutionary mechanism of phosphorus during the hydrothermal conversion of biomass wastes are still unclear. In this study, swine manure was investigated as the research subject, and the changes in its solid-phase organic components, such as lignocellulose, and inorganic constituents, including metals and phosphorus, during the hydrothermal carbonization (HTC) processes were analyzed in relation to hydrothermal reaction severity (LnR₀). A significant linear correlation in Phase II was observed between the solid-phase yield of swine manure and the LnR₀. The rapid decline in the solid-phase yield during the initial phase (LnR₀ < 9.72) was primarily attributed to the hydrolysis of hemicellulose and similar components. Similarly, solid phase phosphorus showed a very significant phase II with the decrease of solid phase yield. In the first stage, inorganic phosphorus and metal ions (calcium ions, magnesium ions) transferred to the liquid phase (LnR₀<9.41). When LnR₀ > 9.41, and the driving force of inorganic phosphorus and metal ions into solid phase is enhanced. As the LnR₀ was further increased, the HTC could fix over 90 % of the total phosphorus content. XANES analysis indicated that hydroxyapatite emerged as the predominant phosphorus fraction in the solid-phase products, comprising more than 60 %, while magnesium ammonium phosphate components also appeared. This research elucidates the underlying mechanisms of component interaction and phosphorus transformation, providing a solid foundation for enhancing the reuse efficiency of phosphorus in wastes.

Urea, an essential organic fertilizer, enhances soil fertility by providing 0.466 nitrogen for maximum crop yield. In this study, urea is synthesized from NH₃ and CO₂ in an equilibrium reaction process adhering to Le Chatelier's principle, maintained under process conditions: flow rate of 63.5 kg/s, temperature of 184 °C, and pressure of 160 kg/cm². A new rate expression model, formulated in terms of extent of reaction and mole fraction, was developed based on mass action relations and thermodynamic models. Two industrial reactors were considered: a plug flow reactor (PFR) at Notore and a continuous stirred tank reactor (CSTR) at Indorama plants. Transient reactor models, based on material and energy balance conservation principles, were numerically resolved using MATLAB version 2020 with specified input conditions. A non-linear regression statistical optimization model was employed to refine kinetic parameter values, ensuring optimal and high-quality urea yield. Model validations were conducted using literature data, revealing higher urea yields of 0.726 and 0.7032 for the CSTR and PFR, respectively. Deviations (0.134, 0.10 to 1.135 and 0.635, 0.326 to 0.850) and root mean square errors (RMSE) (0.043, 0.033 to 0.193 and 0.137, 0.087 to 0.162) were observed when validated against plant and literature values for the CSTR and PFR respectively. The refined kinetic parameters (activation energies, Arrhenius constants, and rate constants) exhibited negligible deviations (0.0004–0.0466 and 0.0004 to 0.0491) and RMSE (0.0228, 0.0055, and 0.0256 and 0.0241, 0.0096, and 0.0269) when validated against plant data, significantly enhancing urea yield in CSTR and PFR reactors respectively.

This study investigates the trajectory and spreading of a horizontal circular dense jet flow discharged above the water surface, the flow of which falls into shallow stagnant ambient water. For this purpose, 27 experiments were performed using three diameters, flow rates, and falling heights to investigate jet trajectory. In addition, nine experiments with constant falling height were conducted to study jet spreading. The densimetric Froude number of the jet flow at the nozzle outlet and water surface of the present study ranged from 0.72 to 4.22 and 36.96 to 86.10, respectively. The data pertaining to this study were extracted and analyzed through image processing. The results of the experiments showed that by increasing both the momentum and falling height, the trajectory of the jet flow reached a farther distance from the discharge nozzle. The spreading of the outer boundaries of the dense circular falling jet flow tended to extend downstream of the impact point and had an elliptical motion on the bed. The relationship between radial distance from the impingement point to the outer boundary of flow and time was determined to have a power of 0.67 for flow along the flume and 0.59 for flow along the flume's width.

Commiphora gileadensis (C. gileadensis) is a plant traditionally used in many parts of the world for medicinal purposes. However, the benefits of this plant are yet to be uncovered due to the use of conventional extraction methods during its extraction. Hence, there is a need for more efficient and environment-friendly extraction methods for optimum recovery of the bioactive components of C. gileadensis. This study aims to evaluate the impact of microwave-assisted extraction (MAE) process parameters (individually and in combination) on the recovery of phenolic compounds from C. gileadensis leaf. One-Factor-At-a-Time (OFAT) optimization method was used in this work to study the impact of varying the MAE process parameters (sample: solvent ratio, microwave power, ethanol concentration, and extraction temperature) on the optimum yield of phenolic compounds. The obtained phenolic compounds were characterized using Gas chromatography-mass spectrometry (GC–MS) for tentative identification of the component phytochemicals of the extract. The results showed that the optimal process condition of microwave power at 300 W, solvent/sample ratio of 1:10 g/mL, solvent concentration of 40 % v/v, and extraction temperature of 40 °C gave the maximum extraction yield of 33.20 ± 0.42 % w/w, total phenolic content (TPC) of 114.65 ± 3.14 mg GAE/g d.w., and total flavonoids content (TFC) of 37.56 mg QE/g d.w.). Furthermore, the GC-MS analysis identified 25 phenolic compounds with good antioxidant activities from the extracts. Therefore, MAE is considered a non-conventional green method for improved extraction of phenolic compounds from C. gileadensis leaf compared to the existing conventional extraction methods.