Liquid Vacuum Research Articles

Dynamic simulation of ion evaporation from a conductive meniscus, fluid-fluid model of plume and meniscus interactions

Ion evaporation from a conductive meniscus has been of significant interest in the theoretical investigation of electro-hydrodynamics and application exploration across various fields. This study focuses on developing a fluid-fluid methodology for the dynamical simulation of a conductive meniscus undergoing ion evaporation and uncovering the interaction between the plume and meniscus using the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate as a case study. In the fluid-fluid model, we propose a simplified fluid plume model to acquire the charge distribution in free space, and validate it against a particle plume model and a full fluid plume model. The meniscus evolution is described by expanding the leaky dielectric model to account for charge conservation in the liquid as well as self-heating and inhomogeneous physical properties. The arbitrary Lagrangian–Eulerian method is used to track the sharp liquid–vacuum interface. Dynamic simulation with the simplified fluid plume model is more than 150 times faster than that with the full fluid plume model. The electrohydrodynamic process of the meniscus evolving to form a droplet is analyzed, with a detailed discussion on the space charge effect caused by evaporated ions. Results indicate that neglecting the space charge effect during conical meniscus formation leads to a singular meniscus tip. Instead, the reverse electric field induced by the space charge suppresses this singularity, assisting the conical meniscus to produce a jet. Additionally, the high-throughput ion evaporation significantly enlarges the diameter of droplet formed on the conical meniscus due to the reverse electric field of space charge.

Research on energy loss mechanism and optimization method of liquid ring vacuum pump based on entropy production theory

To solve the problem of high energy consumption of liquid ring vacuum pumps and serious hydraulic losses that make it difficult to improve the efficiency of the pumps. Firstly, the mechanism of the influence of radical clearance on the energy loss of liquid ring vacuum pumps is investigated, and a directional and quantitative analysis of the energy loss in the flow field within a liquid ring vacuum is made based on the entropy production theory. Then the structural parameter control model oriented to the maximum suction capacity and minimum wall effect entropy production of the liquid ring vacuum pump is established. The results indicate that turbulent entropy production and wall entropy production dominate the energy losses of liquid ring vacuum pumps with radial clearance of 24 mm, 28 mm, 32 mm, and 36 mm. The entropy production caused by the wall effect mainly occurs at the shell of the gas compression region. The optimized liquid ring vacuum pump model achieves an increase in suction capacity of 8.74 %, an increase in isothermal compression efficiency of 3.75 %, and a reduction in wall effect entropy production of 19.7 %.

Optimization of vacuum membrane distillation and advanced design of compact solar water heaters with heat recovery

With the escalating global population, freshwater scarcity has become a pressing challenge. To address this issue, this paper presents a novel compact solar water heater (CSWHT) system incorporating heat recovery and submerged-membrane filtration. The research aims to develop an efficient desalination method that reduces water production costs and maximizes output. The system comprises a feed storage tank, a vacuum membrane distillation (VMD) system positioned atop the submerged CSWHT, a liquid ring vacuum pump (LRVP) utilizing waste heat from the outlet to preheat the feed, and hollow fiber membranes.Three critical parameters, namely the mass of the feed in the storage tank, the number of hollow fiber membrane rows, and the feed volumetric flow rate, were optimized using a multi-objective non-dominated sorting genetic algorithm II (NSGA II) to minimize water production cost (WPC) while maximizing water production. Subsequently, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) was employed to identify the optimal scenario from among the selected best solutions.For Mediterranean seawater and a 6 m2 solar collector area, the multi-objective NSGA II algorithm identified 20 membrane rows per collector, 334.4 kg feed mass in the storage tank, and 0.027 kg.s−1 feed mass flow rate as the optimal system parameters. Under these optimized conditions, the system exhibited a daily production capacity of 92.5 kg water, 4.6 kg chloride, and 0.03 g bromide, while achieving a production cost of 12.2 USD.m−3 and a gain output ratio (GOR) of 1.6. These results highlight the system's remarkable potential for desalination with high efficiency and low cost. Future research should focus on scaling up the system and exploring its applicability in various geographical locations.

Synthesis and characterization of MWCNTs nanocomposite for fabrication of tensometric transducers

A nanocomposite was prepared using MWCNTs and micro-sized bronze particles dispersed in elastomer silicone organic compound (SILAGER 8030). The nano-composite was characterized by FT-IR, SEM, EDS and Raman spectroscopy; showing the rough surface of the composite with interweaving of nano threads. This nano-composite was used to manufacture strain gauge. The conductivities were measured concerning wt% of micro-sized bronze, compression and time. The maximum electrical conductivity obtained was 2.1 S/m at 5.0 wt% bronze metal alloy and MWCNT (3.0 wt%) at 16% compression. With increasing amplitude and frequency of ultrasonic exposure, an increase in the pressure associated with cavitation in the liquid was observed. Each value of ultrasound exposure corresponded to a certain value of electrical resistance. At the same time, with an increase in the intensity of the cavitation effect on the strain gauge transducer, extremum points appeared, which corresponded to a decrease in resistance. The developed material is highly useful for manufacturing strain gauges to be used in liquid ring vacuum pumps as a measuring transducer of liquid ring pressure into signals associated with changes in resistance. This allows liquid ring vacuum pumps to be precisely controlled; improving their energy efficiency and reliability.

Effect of temperature on the drag reduction characteristics of xanthan gum in the liquid ring vacuum pump

Xanthan gum (XG) solution has been proven to be an effective working fluid in the liquid ring vacuum (LRV) pump to achieve significant energy savings. As an important influencing factor of the LRV pump performance, the effect of temperature on the drag reduction performance, rheological properties, and microstructure of XG solution in the LRV pump were experimentally investigated in this paper. The results indicate that with the increase of temperature, the drag reduction rate of the XG solution in the LRV pump initially rise and subsequently decline, and XG solutions with different concentrations show different optimal drag reduction temperatures. The microscopic parallel double-chain structure of XG has the same change pattern as the drag reduction performance, while the steady-state and dynamic shear characteristics of the XG solution manifest a downtrend. For instance, as the temperature of 4000 ppm XG solution increases from 10 °C to 60 °C, the drag reduction rate decreases by 20 %; the parallel double-chain structure decreases from 91.3 % to 89.9 %; the yield stress and relaxation time decrease from 4.63993 Pa to 4477.56 s to 3.37808 Pa and 143.27 s, respectively; the drag reduction rate reaches the maximum value when the temperature is 40 °C.

All in one doubly pillared MXene membrane for excellent oil/water separation, pollutant removal, and anti-fouling performance

Given the diversity and complexity of coexisting oil/dyes/heavy metal ions/microorganisms in wastewater and volatile organic compounds (VOCs) in the air, developing separation materials featured in higher separation efficiency and lower energy consumption for oil and water separation, pollutant removal, and anti-fouling is urgently needed, but it remains a major challenge till now. Herein, a multifunctional Ti3C2 MXene membrane with unique double pillar support was proposed by liquid phase ultrasonication and vacuum filtration to overcome the above challenge. Introducing cetyl-trimethyl ammonium bromide (CTAB) and calcium chloride/sodium alginate (CaCl2/SA) to the MXene membrane as crossed double pillars and superhydrophilic surface increases the tolerance and wettability of the membrane. The fabricated doubly pillared MXene (d-Ti3C2) membrane exhibits superior oil/water (O/W) separation efficiency (99.76%) with flux (1.284 L m−2 h−1) for canola oil and organic dye removing efficiency for methyl blue (MB) 99.85%, malachite green (MG) 100%, and methyl violet (MV) 99.72%, respectively, which is 1.05, 1.44, 1.22, and 1.28 fold compared with pre-pillared Ti3C2 (p-Ti3C2). The superior anti-oil/dye/fouling is attributed to lower oil conglutination, high hydrophily, and antibacterial activity. The versatile MXene membrane also shows distinguished separation of VOCs (η > 99%) from polluted air. The experimental and molecular dynamics (MD) computational simulation results illustrate that the superior separation efficiency of the Ti3C2 MXene membrane is ascribed to the unique doubly pillared space channel. This study paves a new road to further research on one step integration strategy for complex O/W separation, wastewater and VOCs removal, and anti-fouling via tuning nano/macro architecture.

Synthesis of silver nanoparticles from coffee parasite leaf extract (Scurrulla ferruginea (Roxb. ex Jack) Danser) and potential activity as an antioxidant and anticancer

This study aim is to know the results of the synthesis of silver nanoparticles from quercetin and Scurrula ferruginea (Roxb. Ex Jack) danser as well as its potential as an antioxidant and anticancer. The solvent used in the maceration extraction method in this research is the polar solvent methanol. Isolation and purification of thick extract compounds from coffee parasite leaves were carried out using liquid vacuum chromatography (CVC) and gravity column chromatography (GCC) methods. Silver (Ag) nanoparticle is made with the stirrer method at a speed of 1500 rpm for 60 minutes at a temperature of 70o C. Silver nanoparticle solution was produced and then characterized using FTIR (Fourier Transform Infra Red) and PSA (Particles Size Analyzer). PSA results analysis using extract coffee parasite size 214 nm particles, whereas using flavonoid isolate quercetin confirmed size 29 nm. FTIR showed that there was a stretching vibration of the OH group at a wave number of 3229.25 cm-1, the C=O function at the wave number 1637.87 cm-1, and the CO functional group at the wave number 1016.31 cm-1. Antioxidant test using the DPPH method was carried out in silver nanoparticle solution using extract Scurrula ferruginea (Roxb. Ex Jack) danser and with quercetin obtained an IC50 value of around 115.4 and 114.9 this result describes as moderate level of antioxidants. Even though the nanoparticle anticancer test was very weak, overall, the synthesis of silver nanoparticles using flavonoid isolates was better than using extracts from coffee parasite leaves.

Investigation of pyruvic acid photolysis at the air-liquid interface as a source of aqueous secondary organic aerosols

Pyruvic acid (PA) is a ubiquitous 2-oxocarboxylic acid in the atmosphere. Its photochemical process at the air-liquid (a-l) interface has been suggested as an important source of aqueous secondary organic aerosols. We investigated the photochemical reaction pathways of PA at the a-l interface using synchrotron-based vacuum ultraviolet single-photon ionization mass spectrometry (VUV SPI-MS) coupled with the System for Analysis at the Liquid Vacuum Interface (SALVI) microreactor. Results from mass spectral analysis and the determination of appearance energies (AEs) indicate that photolysis of PA can generate radicals, then they recombine with carboxylic acids and simple molecular oligomers. Furthermore, the preliminary products could form larger oligomers via radical reaction or esterification in the presence of hydroxyl and carboxyl functional groups. Mass spectral comparison shows that most photochemical reactions would complete within 4 h. The expanded photochemistry-driven reaction flowchart of PA is proposed based on the newly discovered products. Our results reveal that the interfacial PA photochemical reactions have different mechanisms from the bulk liquid due to the interfacial properties, such as molecular density, composition, and ion concentration. Our findings show that in situ mass spectral analysis with bright photon ionization is useful to elucidate the contribution of a-l interfacial reactions leading to aqSOA formation.

Quantifying the performances of SU-8 microfluidic devices: high liquid water tightness, long-term stability, and vacuum compatibility

Quantifying the performances of SU-8 microfluidic devices: high liquid water tightness, long-term stability, and vacuum compatibility

Silicon carbide nanoparticles featured AZ63/BN alloy nanocomposite made by using liquid stir vacuum die cast: characteristics study

ABSTRACT With the unique class, the reinforcements play a precious role during the composite fabrication, expanding the specific properties. The novel research intensively enhances the micro-structural and mechanical behaviour of magnesium alloy (AZ63/3 wt% boron nitride) nanocomposite featured 2, 4, and 6 wt% of nano-size silicon carbide (SiC) particles via liquid state vacuum stir cast route. The exposure of SiC and BN on composite density, voids contribution, changes in AZ91D microstructure, impact toughness, hardness, and stress-strain individuality of AZ63 alloy nanocomposite is evaluated with ASTM policy. The composite composed with 3 wt% BN and 6 wt% SiC proved their identity. It showed the lower contribution of voids-free homogenous dispersion particle results in a maximum impact strength of 14.7J/mm2, hardness of 74HV, and superb tensile strength of 247MPa. This optimum behaviour will be recommended for automotive roof frame applications.

ISOLATION AND CHARACTERIZATION OF FLAVONOID DERIVATIVE OF ETHYL ACETATE EXTRACT FROM BAUHINIA LATISILIQUA STEM BARK AND ITS ACTIVITY AS ANTIOXIDANT

Various bioactivities on natural compounds, the antioxidant potency can provide a broad spectrum in their utilization and development into medicinal raw material. One of the plants that have potency for antioxidant activity is the Kemerakan sapenit (Bauhinia latisilqua) plant. The study aimed to isolate, characterize, and determine the antioxidant activity of a compound isolated in the ethyl acetate extract of the stem bark of B. latisilqua. This research includes extraction, fractionation, purification, and elucidation of secondary metabolite structure as well as testing its antioxidant activity. Extraction was carried out by maceration technique, fractionation, and purification using liquid vacuum chromatography and gravitation column chromatography. The elucidation of the structural compound was determined by analysis of the UV, IR, and NMR spectra. The antioxidant test was performed using the DPPH method. Based on the analysis of the spectral data, the isolated compound was catechin, a derivative of flavan-3-ol. Antioxidant test on catechin compound showed a strong antioxidant with an IC50 value of 35.01 µg /mL (IC50 for positive control, ascorbic acid, of 42.94 µg /mL).

Potential of purple eggplant skin fraction (Solanum Melongena Var. Serpentinum L.) as an in vitro sunscreen

Sunscreen is a product that is used as skin protection against sun exposure. The skin of purple eggplant is known to contain secondary metabolites which are used as sunscreens. This study aims to determine the activity of sunscreen fraction of the purple eggplant (Solanum melongena var. serpentinum L.) in vitro. Testing of sunscreen activity was carried out by calculating the value of SPF (Sun Protection Factor), %TE (Percent Transmission of Erythema) and %TP (Percent Transmission of Pigmentation) using the UV-Vis Spectrophotometry method. The purple eggplant skin fractionation method is by using LVC (Liquid Vacuum Chromatography). The results of the fractionation were identified using phytochemical screening and combined TLC. The fraction results were tested for SPF (Sun Protection Factor), %TE and %TP values. The results showed that the extract yield was 26.33%. The fractions used are fraction 9; 10; 11; and 12 which showed the same stain after being evaporated, which was a brownish yellow stain with a yield of 21,24%. The purple eggplant skin fraction (Solanum melongena var. serpentinum L.) has SPF, %TE and %TP values with optimal protection at a concentration of 400 ppm with each value obtained being 19; 1.35 and 9.79. The results of the statistical test of the purple eggplant skin fraction showed that the data were normally distributed but not homogeneous. The results of the homogeneity test for each concentration of results showed that the data were not significantly different.

ЖИДКОСТНОКОЛЬЦЕВЫЕ ВАКУУМНЫЕ НАСОСЫ КОМБИНИРОВАННОГО ТИПА ДЛЯ ЭНЕРГОЭФФЕКТИВНЫХ ТЕХНОЛОГИЧЕСКИХ ПРОЦЕССОВ ПЕРЕРАБОТКИ РАСТИТЕЛЬНОГО СЫРЬЯ

The use of one- and two-stage liquid ring vacuum pumps of a combined type for agricultural processes is justified: drying, extraction, vacuum evaporation and transportation of plant materials. The purpose of the article is formulated, which is to develop a method of theoretical calculation for the selection of liquid ring vacuum pumps of a combined type for the presented agricultural processes. Scientists who have been and are currently continuing research on this problem are presented. The general methodology for calculating the speed of action, adjusted for the flow rate and geometric parameters of a liquid ring vacuum pump (LVN), is described. The technological scheme of the processes of two-stage convective-vacuum-pulse drying (DCVID) and extraction is described and the use of a two-stage liquid-vitrochemical drying agent for them is justified. A method for calculating the speed of action based on the technological parameters of the devices used is presented. A method for determining the speed of action for DKVIS and extraction in the case of using pulsed action on the processed plant material is also described. The rationality of creating pulses during DCVIS in an additional container or one housing (when using a multi-body apparatus) is substantiated. A technological scheme of the process of vacuum transportation of dry bulk plant material is described. It is proposed to use a single-stage liquid liquid pump for this process. A method for selecting a vacuum pump based on the required performance and air flow is described. Based on the presented materials, conclusions and conclusions are drawn.

Electric-field-induced ion evaporation from the ionic liquid–vacuum interface

We studied ion evaporation from a planar interface between the room-temperature ionic liquid (RTIL) and vacuum under external electric fields by using molecular dynamics (MD) simulations. We calculated the ion evaporation rate (je) as a function of the electric field normal to the RTIL surface (En), and results under Langevin, dissipative particle dynamics (DPD), and Berendsen thermostats were compared. It was found that DPD thermostat is more suitable for simulating the ion evaporation phenomenon. We also compared results under different methods for applying the electric field (constant potential, constant charge, and constant field methods) and found that je-En curves from the three methods agree with each other. Temporal evolution of electric fields in vacuum was further analyzed, and variations of electric fields over time were traced to the induced electric field between the evaporated ion and RTIL film. This work could guide the selection of proper methods for MD simulations of electrospray in the pure ion regime and lays the foundation to study more complex electrospray phenomena using MD simulations.

РАСЧЁТ КОМБИНИРОВАННОЙ КОНСТРУКЦИИ ЖИДКОСТНОКОЛЬЦЕВОГО ВАКУУМНОГО НАСОСА

Liquid ring vacuum pumps are widely used in many areas of the agro-industrial complex, in particular for milking processes, storage of plant materials, their drying and extraction, as well as pneumatic transport. It has been revealed that one of the main disadvantages of liquid ring vacuum pumps - low efficiency (25-50%) is often caused by hydraulic losses during rotation of the liquid ring on a stationary body, as well as inaccurate physical prerequisites in the equations describing the movement of the liquid ring - a two-phase turbulent flow in the working pump cavity. As a consequence, the pump engineering calculation method leads to overestimated performance characteristics at the design stage. In this regard, a combined design of a liquid ring vacuum pump with a rotating casing has been proposed, in which rotation can be transmitted from the impeller blades to the casing blades (in the case of low and medium speed pump size), through involute engagement, or from the casing blades to the impeller blades (in in case of high and especially high speed of action). The basis for calculating the liquid ring is the continuity equation, the stability condition of the liquid ring and the threshold for the occurrence of cavitation phenomena, as well as a coefficient characterizing the drop in speed for turbulent motion in a bladeless space in areas (suction, maximum, compression, discharge). In this case, the mechanism of movement of the liquid ring in the working cavity of the pump is represented by physical processes in the form of the interaction of two power flows: the hydraulic flow of the working fluid and the thermodynamic flow of the gaseous medium. When calculating the main operating parameter of the pump - the actual speed of action - the evaporation of liquid droplets due to changes in the temperature of the liquid ring was taken into account. The forces acting on the rotating wheel and the rotating body of the combined design of a liquid ring vacuum pump are determined analytically.

ВЫБОР ЖИДКОСТНОКОЛЬЦЕВОГО ВАКУУМНОГО НАСОСА ДЛЯ ШАРОВОЙ МЕЛЬНИЦЫ С ВАКУУМНЫМ ОТВОДОМ

The use of powders is of interest in many industries. At the same time, the degree of grinding of materials depends on the intended purpose; in particular, in the production of paints, it is necessary to ensure a certain fineness of grinding of the pigment. The smaller the particles, the higher its hiding power. However, excessively high grinding fineness may reduce the hiding power of the pigment. It is proposed to grind the pigment in a two-section cylindrical-conical ball mill with vacuum removal of particles of a given degree of grinding. The article describes the design of the mill and shows a diagram of the line for vacuum transportation of the crushed pigment. The purpose of the work is to determine the main parameters of the vacuum line of pneumatic transport when grinding solid organic materials using a ball mill with a vacuum outlet. A method for calculating the geometric, kinematic and dynamic parameters of the developed mill and pneumatic transport line is presented. A significant reduction in energy costs for excess grinding is achieved through timely vacuum removal of crushed particles. The vacuum in the system is created and maintained by a liquid ring vacuum pump. Various options for the operation of the developed installation are described: direct grinding; additional grinding and recirculation of additional liquid generated during the operation of the liquid ring vacuum pump, which further reduces energy costs during grinding

Effect of working fluid temperature on energy dissipation characteristics of liquid ring vacuum pump

Liquid ring vacuum (LRV) pump working fluid temperature has a great influence on its energy efficiency. To improve the energy efficiency of the pump, a new model for the energy dissipation of the LRV pump was established based on the relationship between pump suction capacity, the vaporization loss rate of the working fluid and working fluid temperature. Furthermore, the theoretical model was experimentally verified and quantitatively analyzed. The results showed that the useless power increased and suction capacity decreased with increasing working fluid temperature. When the pump shaft speed was 1500r/min and the inlet pressure was 45kpa, the inlet liquid temperature increased from 15 °C to 45 °C, while the proportion of waste work dissipated by temperature rise of the working fluid significantly decreased from 78.8% to 22.1%. On the contrary, the proportion of the working fluid vaporization, the temperature rise of gas, and the convective heat transfer from the pump outer wall increased. The working fluid temperature positively correlated with the inlet fluid temperature and negative correlated with the inlet flow rate. To further reduce the pump operating temperature, it is necessary to increase the flow rate and reduce the inlet temperature.

The Preparations of Fluorographene Nanosheets and Research in Tribological Properties in High Vacuum.

In this study, fluorographene nanosheets (FG nanosheets) were prepared via the solvent-ultrasonic exfoliation method. The fluorographene sheets were observed using field-emission scanning electron microscopy (FE-SEM). The microstructure of the as-prepared FG nanosheets was characterized by X-ray diffraction (XRD) and a thermal analyzer (TG). The tribological properties of FG nanosheets as an additive in ionic liquids in high vacuum were compared to that of ionic liquid (IL) with graphene (IL-G). The wear surfaces and transfer films were analyzed via an optical microscope, Raman spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The results show that FG nanosheets can be obtained from the simple solvent-ultrasonic exfoliation method. The prepared G nanosheets are a sheet, and the longer the ultrasonic time is, the thinner the sheet is. Ionic liquids with FG nanosheets had low friction and a low wear rate under high vacuum conditions. The improved frictional properties were attributed to the transfer film of FG nanosheets and more formation film of Fe-F.

Study of Liquid Ring Vacuum Pump's Capacity to Reduce Motive Steam Consumption of Gas Removal System in Indonesia's Geothermal Power Plant 117 MW

Study of Liquid Ring Vacuum Pump's Capacity to Reduce Motive Steam Consumption of Gas Removal System in Indonesia's Geothermal Power Plant 117 MW

Designing the technology and composition of plant extracts using reduced atmospheric pressure

The study aims to establish the regimes and parameters of extraction of bioactive substances from raw plant materials by means of extraction with reduced atmospheric pressure for the purpose of manufacturing non-alcoholic functional syrups. The work is performed by leading specialists of the Kemerovo State University using conventional methods. Preparation of the extracts involves aqueous alcoholic treatment of the crushed mass of raw plant materials selected according to the functional parameters. Extraction is performed in a Soxhlet extractor with an advanced liquid ring vacuum pump. The extraction process is monitored by changes in the content of terpenoids in the extract obtained and the mass fraction of dry matter. As a result, the study establishes the parameters and regimes for carrying out and intensifying the extraction of terpenoids and dry matter from fennel, anise, caraway, and dill: pressure – 0.2 MPa, extraction temperature – 50°С, duration of the process – 45 min, solvent – 40 % aqueous alcoholic solution, raw material particle size – 2-3 mm. These process conditions guarantee the highest degree of extraction of terpenoids and dry matter from raw materials, as well as reduce the time and economic costs.