Results in Engineering最新文献

Elastocaloric Ni-Ti alloys offer solid-state heat pump and cooling applications. The environmental impact of elastocaloric Ni-Ti parts manufactured via powder bed fusion was assessed using life cycle assessment with the ReCiPe method. These solid-state heat pumps can mitigate the environmental impacts of current air conditioning/refrigeration methods that use harmful chemicals like CFCs, HCFCs, and HFCs. Measurements of electricity, Ar gas, and compressed air consumption were considered within the gate-to-gate boundary, covering powder transportation, printing, and use-phase. Nickel was identified as the most damaging input, reducible through geometry optimization. Optimized geometries (given the same number of printing layers) require more energy during powder bed fusion however, the environmental benefit from material saving outweighs the damage from increased electrical usage by far. The powder bed fusion machine's standby mode consumes more energy and Ar gas than the printing process, presenting an opportunity for mitigation. Additively manufactured Ni-Ti elastocaloric structures were used as heat generators/sinks in flowing water during compression cycles, achieving 11 °C and 10 °C water temperature change per cycle for the solid geometry and the optimized geometry respectively. A 10 x 10 × 55 mm Ni-Ti structure, providing >2 °C temperature span under compressive cycles, served as the functional unit.

This paper introduces a novel high-speed underwater optical wireless communication (UOWC) system employing three distinct orbital angular momentum (OAM) beams. A single green laser source operating at 532 nm generates these beams: ${\mathrm{LG}}_{0,0},{\mathrm{LG}}_{0,20},\text{and}{\mathrm{LG}}_{0,50}$, each transmitting data at 10 Gbps. The paper provides a comprehensive analysis of absorption and scattering coefficients for five Jerlov water types: I (JI), IA (JIA), IB (JIB), II (JII), and III (JIII). Simulation results demonstrate the system ability to transmit multiple data streams simultaneously using distinct OAM modes, achieving an overall capacity of 30 Gbps. The longest underwater (UW) transmission distance of 22 m is achieved in JI water as it exhibits the lowest attenuation. This range decreases by 9.09 %, 31.82 %, 59.09 %, and 80.91 % in JIA, JIB, JII, and JIII, respectively, due to increased attenuation in these water types. These results are obtained with a log (BER) below −5 and a Q-factor above 4, indicating successful data reception. The findings highlight the potential of OAM multiplexing for enhancing data capacity in challenging underwater environments.

The sewage sludge ash (SSA) is characterized as a by-product used in the pavement industry to mitigate the environmental risks, enhance the landfill capacity and conserve the non-renewable resources. This research utilized SSA as a filler substitute in asphalt mastic, and its performance-based properties from low towards high temperatures were evaluated. For this goal, the physical and chemical properties of SSA and rock powder (used as base filler) were determined using BET surface area measurement, X-ray fluorescence, and scanning electron microscopy tests. The performance of base and SSA-modified asphalt mastics in four filler/bitumen weight ratios (0.6, 0.8, 1, and 1.2) was investigated using dynamic shear rheometer, multiple stress creep and recovery, linear amplitude sweep, and bending beam rheometer tests across a wide temperature range. The results indicate that SSA has a higher specific surface area, better bitumen absorption, and lower density compared to the base filler. Additionally, unlike the acidic nature of the base filler, SSA possesses strong basic properties, leading to a stronger chemical bond with bitumen and enhanced resistance to aging, particularly at high temperatures. Moreover, the lower density of SSA escalates the amount of filler per unit volume of the SSA-modified asphalt mastic, leading to the increased stiffness and elasticity. This trend improves resistance to permanent deformation and cracking at medium temperatures, although it has an adverse effect on performance of mastic at low temperatures. Moreover, due to the improved performance of SSA-modified asphalt mastic, this study can contribute to the sustainable development of the pavement industry.

A novel mechanism is proposed to simultaneous recovery and storage of energy for use in the natural gas depressurization process. The main idea of this proposal is to use a compressor and a pump coupled with the turbo-expander to directly store the mechanical power produced by the expansion turbine in the energy storage system based on the pumped hydro combined with compressed gas. The compressor is used to create preset pressure in the vessel of the energy storage system, and the pump is used to inject water into the vessel. In this way, the density of energy storage in the system increases. In the discharge stage, electricity is produced by passing water through the turbo-generator during peak consumption hours or when energy prices are higher. The capability of the presented new method has been tested in a natural gas pressure reducing station with a nominal capacity of 50,000 Nm³/h, and the effect of different factors within the energy storage system on its performance, including the preset pressure and the volumetric ratio of water to gas in the pressurized tank, has been studied. By using the proposed plan, due to the elimination of unnecessary energy conversions the efficiency of recovery, storage and release of energy enhances. The results showed that by employing the proposed system, about 1.3 (GWh) of energy can be harvested annually; while this amount of energy is currently wasted. Also, the overall energy conversion efficiency of 48.64 %.

This study focuses on optimizing the concentrations of water and 1-pentanol in biodiesel-diesel blends derived from Gossypium hirsutum (cottonseed) oil to enhance engine performance and reduce environmental impact. Biodiesel from cottonseed oil (COB) was produced via transesterification, followed by an analysis of its elemental and chemical composition, and physicochemical properties. Using a Box-Behnken design matrix, the volume concentrations of COB (10–30 %), water (5–15 %), and 1-pentanol (5–20 %) in diesel fuel were varied to optimize engine performance and emission characteristics. ANOVA was employed to evaluate the influence of these parameters on key output responses. The results demonstrated that COB possesses favorable elemental and chemical properties, and the optimal concentrations of COB, water, and 1-pentanol were identified as 14.7 %, 9.9 %, and 11.2 %, respectively. ANOVA findings revealed that COB had the maximum influence on brake specific fuel consumption (93.4 %), nitrogen oxides (55.3 %), carbon monoxide (78.5 %), and carbon dioxide (97.1 %), while 1-pentanol significantly influenced brake thermal efficiency (38.9 %) and hydrocarbon emissions (70 %). Confirmation experiments validated these optimizations, showing substantial improvements in both performance and emissions. The study concludes that integrating water and 1-pentanol into COB blends can reduce fossil fuel consumption by approximately 35 %, while enhancing energy efficiency and minimizing environmental impact.