Search Results (86)

Amid the ongoing decarbonization of the international shipping industry, methanol has emerged as a promising alternative fuel for marine auxiliary boilers owing to its environmental advantages and engineering feasibility. However, its low viscosity and surface tension make the atomization process highly sensitive to operating conditions, posing challenges to stable and efficient burner operation. Existing studies have predominantly focused on engine applications, whereas systematic investigations into the atomization characteristics and operating-parameter matching of primary-air swirl-cup nozzles for marine auxiliary boilers remain limited. To address this gap, the present study combines experimental measurements and numerical simulations to investigate the effects of fuel flow rate, atomizing-cup rotational speed, and primary-air damper opening on spray characteristics. Spray imaging was employed to characterize the spray cone angle and macroscopic morphology, while PIV and PDA were used to measure the outer-flow-field velocity and droplet-size characteristics, respectively. Numerical simulations of liquid-film formation and breakup were performed using a coupled VOF-DPM framework. The predicted spray angle and outer-flow-field velocity showed good agreement with the experimental measurements, with overall deviations within 3–12%. Increasing the atomizing-cup speed generally promoted droplet refinement, while adjustment of the primary-air supply further influenced the droplet-size distribution. Under high-speed operating conditions, the atomized droplet size was generally maintained below 100 μm, and the SMD in the investigated near-field region was approximately 60–80 μm. Based on the multi-load experimental results, primary-air parameter-matching relationships were established for fuel flow rates ranging from 100 to 500 kg/h, providing guidance for maintaining stable atomization performance over a wide operating-load range. This study provides a quantitative basis for the operating-parameter design and stable operation of primary-air swirl-cup nozzles in marine methanol-fired auxiliary boilers and offers useful guidance for their engineering application. Full article

This study presents a 3D computational fluid dynamics (CFD) investigation of methane and methanol combustion in a medium-speed, large-bore marine spark-ignition engine equipped with a pre-chamber (PC) ignition system. Simulations were performed in ANSYS Forte at 100%, 80%, and 20% engine load. Methane operation with an active PC was used as the reference configuration, while methanol was investigated with both active and passive PC. A preliminary injection-timing analysis was conducted for the active methanol configuration to obtain a near-stoichiometric and sufficiently homogeneous mixture inside the PC at spark timing (ST). The results show that active methanol operation promotes earlier heat release, shorter combustion duration, and higher thermal efficiency than methane operation. The active PC generates stronger turbulent reacting jets and ensures more robust combustion than the passive configuration. Methanol also considerably reduces NO_x emissions because of its lower initial and combustion temperatures. However, active methanol operation increases CO emissions, particularly at low load, because of incomplete oxidation associated with low temperatures, mixture inhomogeneity, and possible spray–wall interaction. The passive PC further reduces NO_x and CO emissions but causes delayed combustion, lower thermal efficiency, higher fuel consumption, and tank-to-wake CO₂ emissions than the active methanol configuration. Full article

This study presents a systematic mapping of methanol spray autoignition, lift-off, and flame development across an engine-relevant range of ambient temperatures (1000–1200 K), injection pressures (70–130 MPa), and O₂ concentrations (21–15 vol.%), using a single fixed injector and optical configuration. In addition, the study reports a dual-fuel strategy to address the low-temperature instability challenges highlighted by the mapping. Within this dataset, ignition delay increases with a lower ambient temperature, reduced injection pressure, or a lower O₂ concentration, while the lift-off length increases with a lower temperature and higher injection pressure. Schlieren imaging consistently captures ignition in the mid-axial region of the jet, softening of spray-head gradients before high-temperature ignition, and occasional upstream ignition sites during the diffusion-controlled phase that affect the flame base position. At the lowest tested temperature of 1000 K, methanol autoignites over a wide ignition-delay range (±1.33 ms), with combustion occurring outside the chamber’s field of view. The corresponding heat-release profile cannot be interpreted conclusively under the current test configuration. Introducing a pilot jet at this condition enables methanol to ignite shortly after the start of injection over a much narrower range (∼±0.10 ms). The resulting combustion event remains within the field of view and occurs much closer to the nozzle compared with its autoignition counterpart. Full article

Methanol compression-ignition engines are vital for transport carbon neutrality, yet methanol’s low cetane number, corrosivity, low viscosity, and cavitation tendency compromised piezoelectric injector reliability. This study proposed systematic optimization strategies tailored to methanol’s fuel properties. A sealed thin-walled metal encapsulation, fabricated from precipitation-hardening martensitic stainless steel, was designed to isolate corrosive methanol media. The geometry of the tubular spring was optimized to meet the stiffness requirements for high-frequency injections. A monolithic nozzle without side pin holes, also upgraded to the same precipitation-hardening martensitic stainless steel, effectively suppressed stress corrosion cracking by leveraging the material’s combined high strength and excellent corrosion resistance. A dedicated return-line backpressure valve compensated for hydraulic leakage and improved fuel replenishment, and nozzle hole taper and inlet fillet radius were optimized to mitigate cavitation. Cold-motoring reliability tests showed the optimized injector maintained flow deviation within 3% after 100 million cycles, whereas the unoptimized prototype reached 8% deviation at 60 million cycles. The single-cycle injected fuel quantity coefficient of variation dropped from 4% to 1.3%. Spray characteristic comparison tests further confirmed that the optimized injector maintained stable flow consistency and atomization quality after prolonged cyclic operation. These optimizations effectively resolved corrosion, wear, and hydraulic instability caused by methanol, significantly enhancing flow consistency and durability over the service life. The results provided critical component-level technical support for advancing methanol compression-ignition engines from laboratory research to industrial application, addressing key reliability barriers that previously hindered engineering deployment of methanol-fueled powertrains. Full article

This study presented a comprehensive optimization of a piezoelectric injector specifically designed for pure methanol compression-ignition engines. As a fuel for compression-ignition engines, methanol exhibits broad application prospects. To overcome the challenges posed by methanol’s low cetane number and energy density, a co-optimization strategy was implemented, targeting the actuator, drive waveform, and internal flow geometry. The redesigned injector exhibited superior dynamic performance, featuring significantly faster response times and enhanced operational stability, which were critical for precise fuel delivery control. Furthermore, the optimized internal flow path increased the effective flow rate, ensuring sufficient fuel supply across all engine operating conditions. The upgraded injector was rigorously tested on an engine bench, demonstrating substantial performance gains. Brake thermal efficiency improved from 38.9% to 40.4% at low load and from 43.68% to 46.07% at high load. Emissions of CO, formaldehyde, acetaldehyde, and unburned methanol were consistently reduced, with the maximum reduction reaching 23.1%, confirming markedly enhanced combustion completeness. This improvement was directly attributed to the injector’s refined spray characteristics and precise control, although it led to a slight increase in NOx emissions due to higher peak combustion temperatures. Full article

Hydrogen enrichment of compression ignition (CI) engines has emerged as a promising strategy to simultaneously enhance thermal efficiency and reduce carbon-based emissions. This study numerically investigates how hydrogen enrichment affects engine performance and emissions in methanol–diesel dual-fuel CI engines, a combustion mode gaining increasing attention for replacing fossil diesel with sustainable fuels, particularly in hard-to-abate sectors such as maritime transport. The simulations are based on the Unsteady Reynolds-Averaged Navier–Stokes (URANS) equations, incorporating the RNG k-ε turbulence model, the Eddy Dissipation Concept (EDC) for turbulence–chemistry interaction, and the G-equation for turbulent premixed flame propagation. The numerical model is validated against experimental data for in-cylinder pressure and heat release rate at 45% methanol substitution ratio (by energy). The results indicate that increasing the hydrogen enrichment ratio (HER, defined on an energy basis) from 5% to 20% raises the Sauter mean diameter (SMD) of the diesel fuel from 20.2 µm to 28.0 µm (+38%), driven by reduced aerodynamic breakup intensity associated with modified gas-phase properties under hydrogen enrichment. Furthermore, hydrogen’s elevated adiabatic flame temperature and superior mass diffusivity intensify combustion, raising peak in-cylinder pressure from 75.2 to 79.1 bar (+5.2%), amplifying the peak heat release rate from 129 to 211 J/°CA (+63.6%), and elevating maximum in-cylinder temperature from 1542 to 1735 K (+193 K). Under the investigated CFD operating conditions, these thermodynamic gains translate into an engine-level 6% improvement in indicated thermal efficiency and a 14% reduction in indicated specific fuel consumption (accounting for hydrogen, methanol, and diesel) at HER 20%. On the emissions front, CO₂ declines by 24% in direct proportion to the carbon-containing fuel mass displaced by hydrogen substitution, while NO_x increases approximately twofold from 0.10 g/kWh at HER 0 to 0.21 g/kWh at HER 20, driven by peak temperature elevation. These findings establish hydrogen-enriched methanol–diesel dual-fuel combustion as a viable pathway toward high-efficiency, low-carbon CI engine operation for heavy-duty transport applications. Full article

The identification of dyes in ancient textiles is crucial for provenance research and scientific conservation. However, the extremely significant value of these cultural relics necessitates the use of non-destructive analytical techniques. To establish a non-destructive, in-situ, accurate, and rapid method for identifying natural dyes in ancient silk fabric samples, we employed desorption electrospray ionization high-resolution mass-spectrometry imaging (DESI-MSI). By optimizing key instrumental parameters—including sample pretreatment method, DESI spray solvent composition, and DESI heated transfer line (HTL) temperature—we determined the optimal mass-spectrometry imaging conditions. The optimal conditions for achieving the highest mass-spectrometry ion peak signal intensity and the best imaging quality were as follows: employing sample pretreatment using double-sided adhesive tape; a spray solvent composed of methanol (100%, v/v) with 0.1% formic acid and 0.1 μg/mL of leucine enkephalin; and an HTL temperature of 400 °C. The characteristic compound in the G42 silk fabric sample was successfully separated. Based on the characteristic mass-to-charge ratio of the major component, the compound was preliminarily identified as berberine. This result was further verified by tandem mass-spectrometry imaging and tandem mass spectra and finally confirmed by comparison with the mass spectrum of a reference standard. Consequently, the source of the dye in the sample was determined to be amur cork tree. The experiments confirmed the applicability and accuracy of the DESI-MSI method for the non-destructive analysis of precious textiles. This work underscores the urgent need to use such non-destructive techniques to provide technical support for the identification of high-value, inaccessible, or fragile silk artifacts and guide the historical tracing and preservation of these cultural relics. Full article

Phytic acid (PA), owing to its strong acidity and multidentate metal-chelating properties, readily forms multiple adduct/complex ions in mass spectrometry and is prone to pronounced matrix effects, resulting in complicated spectra and compromised sensitivity and quantitative robustness, which poses a major challenge for rapid and accurate PA quantification. Herein, we developed a rapid quantitative method for PA based on trimethylsilyldiazomethane (TMSD) methyl-ester derivatization coupled with paper spray mass spectrometry (PS–MS). PA was derivatized with TMSD to yield the methylated product (PA-Me), and the derivative solution was purified via “post-derivatization nitrogen blow-down followed by water reconstitution”, thereby markedly reducing background interference. In positive-ion mode, the stable sodium adduct ion [PA-Me+Na]⁺ (m/z 851.04) was used as the quantifier, enabling fast quantification with selected ion monitoring (SIM). PS–MS was performed with a 15 μL spotting volume and methanol/water (90/10, v/v, containing 0.1% formic acid) as the spray solvent, allowing rapid analysis without chromatographic separation. The method exhibited good linearity over 0.125–30 μg/mL (R² ≥ 0.9965), with a limit of detection (LOD, S/N = 3) of 0.080 μg/mL and a limit of quantification (LOQ, S/N = 10) of 0.270 μg/mL. The intra-day and inter-day precision values were both < 10% (RSD), and recoveries ranged from 87.2% to 122.4%. This LC-free strategy features low solvent consumption and high analytical throughput, and was validated using rice bran protein and rice bran polysaccharide samples, providing technical support for rapid screening and quality control of PA in complex food/plant matrices. Full article

To reveal the physical evolution of methanol spray under different environmental conditions and injection strategies, this study focuses on the atomization and evaporation behavior of low-pressure methanol spray. The coupled effects of temperature, pressure, and injection parameters are systematically investigated based on constant-volume combustion chamber experiments and three-dimensional CFD simulations. The formation, evolution, and interaction mechanisms of the liquid column core and cooling core are revealed. The results indicate that temperature is the dominant factor influencing methanol spray atomization. When the temperature increases from 255 K to 333 K, the spray penetration distance increases by approximately 70%, accompanied by a pronounced shortening of the liquid-core length and enhanced evaporation and air entrainment. Under low-temperature conditions, a stable liquid-core structure and a strong cooling core are formed, characterized by a high-density, long-axis morphology and an extensive low-temperature region, which suppress fuel–air mixing and ignition. Increasing the ambient pressure improves spray–air mixing but reduces penetration; at 255 K, increasing the ambient pressure from 0.05 MPa to 0.2 MPa increases the spray cone angle by approximately 10% while reducing the penetration distance by about 50%. Furthermore, optimizing the injection pressure or shortening the injection pulse width effectively enhances atomization performance: increasing the injection pressure from 0.4 MPa to 0.6 MPa and reducing the pulse width from 5 ms to 2 ms increases the penetration distance by approximately 30% and reduces the mean droplet diameter by about 20%. Full article

This study presents experimental research on the injection of water–methanol mixtures under both subcooled and superheated conditions. Injecting superheated liquid results in the formation of flash-boiling sprays, generating smaller droplets compared to non-superheated conditions. This improved atomisation leads to a decrease in spray penetration and evaporation time. The mixture of water and methanol is a non-azeotropic mixture, meaning it exhibits different bubble and dew points. Non-azeotropic mixtures are the most common type of mixture. This study investigates the atomisation characteristics of water–methanol mixtures injected under low pressure (0.5 MPa) into a quiescent ambience. The experiments were conducted in an open environment at 1-atm absolute pressure and 22 °C temperature. Five different compositions were tested, including pure water, pure methanol (99.9%), and mixtures with water–methanol volume ratios of 75/25, 50/50, and 25/75. Using laser shadowgraphy with long-distance microscopy, droplet size distributions were measured at four distinct locations. Under high superheat conditions, the droplet distribution was similar for all mixtures. The Sauter mean diameter (SMD) rapidly decreased for all liquids when subjected to superheated injection. This led to the conclusion that the composition of non-azeotropic substances has little significance in terms of droplet diameter at high superheat. Full article

Background/Objectives: Rutin, a bioactive flavonol glycoside known for its antioxidant, anti-inflammatory, and anticancer activities, faces limited clinical application due to its poor aqueous solubility and low oral bioavailability. This study aimed to enhance the dissolution of rutin by preparing solid dispersions (SDs) using a fluid-bed coating system and formulating the resulting SDs into tablet dosage forms. Methods: Rutin was dissolved in methanol and sprayed onto various carriers, including lactose monohydrate, mannitol, microcrystalline cellulose, silicon dioxide, and calcium carbonate. Results: Among the carriers tested, lactose monohydrate produced the highest dissolution enhancement, achieving complete drug release within 15 min versus approximately 60% for free rutin. Further investigation into the effect of the rutin-to-lactose ratio on dissolution enhancement identified 1:10 as the most effective. Characterization by powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC) confirmed a marked reduction in rutin crystallinity, while scanning electron microscopy (SEM) revealed reduced particle size and successful adsorption onto the carrier. Fourier transformed infrared (FT-IR) analysis suggested hydrogen bonding interactions between rutin and lactose monohydrate, which contributed to improved dissolution. The optimal SD was incorporated into tablets containing 50 mg of rutin via wet granulation, and the inclusion of sodium lauryl sulfate further enhanced dissolution. Stability testing demonstrated that the optimized tablets maintained their dissolution profile after 6 months under accelerated conditions (40 °C and 75% RH). Conclusions: These findings indicate that fluid-bed coating is an effective approach for preparing SDs to improve the dissolution of rutin and may be extended to other natural polyphenolic compounds. Full article

The methanol oxidation reaction was investigated on Co- and/or Ag-based γ-Al₂O₃ catalysts, which were prepared by different methods (WI: wet impregnation and SI: spray impregnation) and further doped with noble metals (Pd, Pt). During the present study, three different reaction pathways were revealed. The complete oxidation of methanol to CO₂ and H₂O was achieved on Pd-doped catalysts prepared by the spray impregnation method (Pd-Co/Al-SI and Pd-Ag/Al-SI), while partial oxidation to intermediates such as formaldehyde was observed for Ag/alumina catalysts. The dehydration reaction of methanol to dimethyl ether was carried out on Co/alumina, Ag-Co/alumina, and Pt-Co/alumina catalysts. The improved reducibility of the 5Co/Al-SI catalyst with the incorporation of Pd, combined with the easier surface oxygen desorption, resulted in higher catalytic activity compared to the Pt-doped catalyst. On the other hand, the incorporation of Pd into Ag/Al-SI enhanced the well-dispersed Ag₂O species, mainly affecting the structural properties of the catalyst, thus resulting in partial oxidation of methanol. The 0.5 wt.% Pd-5 wt.% Co/γ-Al₂O₃ catalyst, prepared by the spray impregnation method, exhibited the highest methanol oxidation efficiency (T₅₀: 43 °C) and was further evaluated in the presence of H₂O and CO in the feed for several hours on stream and at reaction temperature of 230 °C. The presence of impurities initially reduced the catalyst’s activity from 100% methanol conversion (in the absence of H₂O and CO in the feed) to 80%; however, over time complete methanol oxidation was regained (achieving again 100% methanol conversion after 12 h on stream). Characterization of the used catalyst (after the stability experiment) revealed that in addition to the Co₃O₄ phase, initially formed in the fresh, as-prepared catalyst, some Co₃O₄ species were reduced to CoO under the reaction conditions, suggesting that the active phase of the 0.5Pd-5Co/Al-SI catalyst for the methanol oxidation reaction in the presence of the impurities (such as H₂O and CO) is probably a mixture of Co₃O₄ and CoO phases. Full article

With the increasing global demand for environmental protection and sustainable energy utilization, methanol, as a clean and renewable fuel, has become a research focus in the field of marine engines. However, its application in compression ignition engines faces bottlenecks such as low combustion efficiency and poor stability. Taking the L23/30H marine diesel engine as the research object, this paper establishes a combustion simulation model for a methanol/diesel dual-fuel direct-injection engine. The reliability of the model is ensured through grid independence verification and model calibration, and a coupled chemical reaction kinetic mechanism containing 126 species and 711 elementary reactions is constructed. A systematic study is conducted on the effects of injection strategies, including fuel operating modes, spray development patterns, injection intervals, and injection timing, on combustion characteristics. The results show that under the optimized injection strategy (vertical cross spray + synchronous injection) proposed in this study and operating conditions with a high methanol substitution ratio, the combustion efficiency, dynamic performance, and soot emission control effect of the dual-fuel mode are superior to those of the pure diesel mode. Simulation results show that the combined strategy of vertical cross injection and synchronous injection can significantly increase the indicated thermal efficiency (ITE) by 3.2%, reduce the brake specific fuel consumption (BSFC) by approximately 4.5%, advance the peak heat release by 2 °CA, and remarkably improve the combustion efficiency, while earlier injection timing is beneficial to air–fuel mixing. Further comparison of combustion and emission characteristics under different boundary conditions such as methanol energy ratios and injection pressures reveals that increasing methanol injection pressure, compression ratio, and initial pressure can improve combustion uniformity and reduce soot emissions, but NO_x emissions increase, which requires the coordination of after-treatment technologies. Through the comprehensive optimization of multiple parameters, efficient and clean combustion under a high methanol substitution rate is achieved. This paper provides theoretical support and practical guidance for the technological development of marine methanol dual-fuel engines. In the future, industrial applications can be promoted by combining actual engine tests and after-treatment technologies. Full article

Paper spray ionization mass spectrometry (PSI-MS) enables rapid analysis with minimal sample preparation, yet negative-ion mode performance has been limited by poor sensitivity and unstable signals, similar to conventional electrospray ionization. In this study, we optimized negative PSI tandem MS (MS/MS) for twelve endocrine-disrupting chemicals (EDCs) and related biomarkers—including bisphenols, phthalates, parabens, and substituted phenols—used as model analytes. A systematic solvent and additive screen identified 1 mM ammonium fluoride in methanol and 0.1% ammonium hydroxide in 9:1 MeOH/carbon tetrachloride as optimal conditions, providing enhanced deprotonated-ion intensities and improved stability. Calibration curves generated under these conditions showed excellent linearity, with limits of quantitation (LOQs) in the low-ppb range. Application to cosmetic formulations demonstrated reliable paraben quantitation. In fortified hand cream, LOQs below 1 mg/kg were achieved, with recoveries of 93–110% and intra- and inter-day precision below 10% RSD. Notably, PSI-MS/MS performance was comparable to LC–MS/MS, without a separation step. These results demonstrate the feasibility of optimized negative PSI-MS as a sensitive and robust tool for paraben determination in cosmetics and highlight its potential as a versatile platform for broader EDC quantification. Full article

In order to develop a new environmentally friendly microbial herbicide for the field of weed control, this study used the metabolite butyl hydroxybenzoate (BP) of the HY-02 strain of Alternaria as the research object. The BP emulsion formula was determined to be a mixture of BP, methanol, and Tween-20 in a ratio of 1:1:2 g/mL. The seed germination inhibition effect, the phytotoxicity of living plants, crop safety, and the field effect of the emulsion were studied. Research has found that adding 0.75% BP emulsion to the seed culture medium inhibits the germination of weed seeds such as Amaranthus retroflexus L., Malva verticillata L. var., and Chenopodium album L. While Brassica campestris L. seeds were unaffected, Triticum aestivum L and Hordeum vulgare L. stem and leaf growth were inhibited. Cucumis sativus L., Lactuca sativa L. var. asparagina, Spinacia oleracea L., and Capsicum annuum L. seeds are significantly inhibited, with germination rates below 20%. We sprayed 0.75% BP emulsion onto live potted plants; among the weeds, the incidence of Amaranthus retroflexus L., Lepyrodiclis holosteoides, Thlaspi arvense L, Galium spurium L., Malva verticillata L. var. Crispa, Chenopodium album L., and Avena fatua L reached 100%. The Pisum sativum L. and Triticum aestivum L. crops were not affected (NS), and they had slight plant height inhibition and slight susceptibility (LS) to highland Hordeum vulgare L. and peppers. They were highly phytotoxicity to Cucumis sativus L. and Spinacia oleracea L. Some plant leaves became infected and died, with incidences of 85% and 82%, respectively. The field experiment showed that after diluting the BP emulsifiable concentrate, the seedling stage spray was inoculated into the Triticum aestivum L. field, and it was found that the BP emulsifiable concentrate at the concentration of 1.00%~0.75% had a herbicidal effect on weeds such as Chenopodium album L., Elsholtzia densa Benth, and Amaranthus retroflexus L. in the Triticum aestivum L. field, and it was safe for Triticum aestivum L. crops in the field. These results indicate that BP emulsion could be developed into a new environmentally friendly microbial herbicide for field application in grass (Triticum aestivum L. and Hordeum vulgare L.) crops. At the same time, BP’s excellent antibacterial, low-toxicity, hydrolysis, and other effects can promote diversification in herbicide development. Full article