Suspension Of Carbon Particles Research Articles

Вивчення високотемпературного тепломасообміну двофракційних газозависів і поодиноких вуглецевих частинок в нагрітому повітрі

In the work, the regularities of high-temperature heat-mass exchange in two-fraction gas suspensions of carbon particles in heated air are studied. These studies are relevant for predicting high-temperature processes in combustion chambers and determining the main characteristics of these processes: induction period, time and temperature of combustion, critical parameters of ignition and extinction. Physico-mathematical modeling of the problem is carried out on the basis of the equations of heat and mass transfer and chemical kinetics for the components of the gas suspension, taking into account the molecular-convective and radiation mechanisms of heat transfer. The characteristics of ignition, burning, and extinction of a two-fraction gas suspension of carbon particles with equal mass concentrations of small (60 μm) and large (120 μm) fractions in the temperature range of 1100 ÷ 1500 K were studied; a comparison was made with the characteristics for single particles of the corresponding diameters. It has been proven that when the gas temperature decreases, the induction period of the fine fraction can exceed the induction period of the large fraction, while the combustion temperature of small particles becomes lower than the combustion temperature of large particles. At high gas temperatures (1400K, 1500K), the situation changes to the opposite. The critical ignition and extinction parameters of two-fraction gas suspensions (gas temperatures, particle diameters) were found.

Flexible construction of three-dimensional continuous conductive structure by hollow carbon sphere and CNT for promoted ions transport in flow-electrode capacitive deionization

Flow-electrode capacitive deionization (FCDI) emerges as a promising desalination technique, characterized by its unlimited desalination capacity, seamless operation, and easy scalability. However, challenges such as discontinuous electronic network, inadequate dispersion of suspended carbon particles, and hindered electron/ion transport pathways have impeded the full potential of FCDI. This study addresses the above issues by synergistically leveraging the advantage of hollow carbon sphere (HCS) and CNT to construct a flexible, continuous three-dimensional conductive network (HCS@CNT) as the flow-electrode for FCDI. The incorporation of HCS substantially improves the fluidity and effective collision of the flow-electrode slurry. Simultaneously, the bridging effect of CNT facilitates smooth ion transport routes and rapid electron/ion transfer. Moreover, the spherical structure of HCS as a node can effectively alleviate the agglomeration of CNT due to its inherent good fluidity. As a result, the meticulously designed HCS@CNT flow-electrode demonstrates outstanding rheological behavior with excellent hydrophilicity, a large specific capacitance, and low ion diffusion resistance. During desalination tests, the HCS@CNT flow-electrode exhibited a high average salt removal rate (0.56 µmol min−1 cm−2), appropriate energy-normalized removal salt (15 µmol J−1), and notable charge efficiency (89 %) in a 1 g L-1 NaCl solution. Impressively, it maintained good stability and continuity over a continuous 10-hour desalination process, showcasing substantial potential for treating highly concentrated saline water. In addition, density functional theory (DFT) calculations provided additional insights, confirming that the construction of HCS@CNT facilitated interfacial charge transfer and electron transport from HCS to CNT. This innovative approach sheds light on enhancing electron/ion transfer by harnessing the unique structural characteristics of the flow-electrode.

Study of the influence of external heat and mass exchange on the features of combustion and extinction of gas suspensions of carbon particles

In the work, the regularities of the influence of heat and mass exchange of gas suspensions of carbon particles with the external gas environment on the processes of ignition, burning and quenching at different mass concentrations of carbon fuel are studied. A monodisperse gas suspension of carbon particles located in a gas heated to a high temperature, which contains an oxidant, is considered. As a result of the conducted physical and mathematical modeling, the following characteristics of high-temperature processes were determined: induction period, burning time and time of complete transformation of particles, critical parameters of ignition and extinction of particles. The influence on these characteristics of the initial particle diameter, mass concentration and temperature of the surrounding gas was analyzed. It was found that the external heat and mass exchange has a slight effect on the induction period and critical parameters of the ignition of gas suspensions, but it has a sufficiently strong effect on the characteristics of the combustion and extinguishing processes. The existence of an upper limit for fuel concentrations and particle diameters at which complete combustion of gas suspensions is not observed in the absence of external mass transfer is proved. Ranges of mass concentrations were found for which complete conversion of carbon fuel burning in the form of gas suspensions is carried out. It is shown that for open gas suspensions, the range of mass concentrations, where complete transformation of particles is observed, expands to the side of large values. The diameters of the particles characterizing the quenching of gas suspensions, taking into account the external mass transfer, are smaller, as a result of a greater supply of oxygen to the volume of the gas suspension.

Carbon black-containing self-healing adhesive hydrogels for endoscopic tattooing

Endoscopic tattooing with India ink is a popular method for identifying colonic lesions during minimally invasive surgery because it is highly challenging to localize lesions during laparoscopy. However, there is a perceived unmet need for the injection of India ink and carbon particle suspension due to various complications and inconstant durability during the perioperative period. In this study, carbon black-containing self-healing adhesive alginate/polyvinyl alcohol composite hydrogels were synthesized as endoscopic tattooing inks. Alginate (Alg) conjugated with phenylboronic acid (PBA) groups in the backbone was crosslinked with polyvinyl alcohol (PVA) because of the dynamic bonds between the phenylboronic acid in alginate and the cis-diol groups of PVA. The carbon black-incorporated Alg-PBA/PVA hydrogels exhibited self-healing and re-shapable properties, indicating that improved intraoperative localization could be achieved. In addition, the adhesive tattooing hydrogels were stably immobilized on the target regions in the intraperitoneal spaces. These carbon black-containing self-healing adhesive hydrogels are expected to be useful in various surgical procedures, including endoscopic tattooing.

Suspended hydrophilic carbon anodes to enable fully flowable cerium–metal hybrid flow batteries

Hybrid redox flow batteries (RFBs) are a special type of RFBs that involve depositing reactions on negative electrodes. The available volume in negative electrodes for cell stacks limits the totally energy-storing capability of these batteries. This paper introduces the first fully flowable Ce–metal flow battery operated with a semisolid, flowable anolyte. Using the semisolid fuel cell concept, we incorporate the sustainable and deposit-abundant features of non-Li-based batteries into the structure of RFBs to develop a fully flowable RFB system. Solid suspension electrodes of hydrophilic carbon particles deposited by earth-abundant metals with redox activity are investigated as alternatives to the redox-active molecules employed in typical RFBs to decouple the power delivery capability from the energy storage capacity in fully flowable RFBs. While being charged, earth-abundant redox-active metal (Cu, Pb or Zn) is electrodeposited on the carbon particle suspension, which is dissolved in the sequent discharging process. On the basis of the proposed contact-charge-transfer mechanism, the electrical contact to the solid suspension electrode is fed by the redox-inert hydrophobic current collector that restrains direct metal deposition on their surfaces due to the hydrophobicity.

High-Temperature Heat and Mass Transfer and Critical Phenomena in the Gas Mixtures of Carbon Particles

The influence of internal reactions on the characteristics of high-temperature heat and mass transfer and the critical conditions for the ignition and the extinction in gas suspensions of carbon particles are researched. It is found that the internal reactions lead to asignificant decrease in the ignition delay and critical diameters, which determines the ignition and the extinction of particles of a gassuspension. It is proven that the porous particle extinguishes when its mass achieves some critical value. The intervals of initial diameters and mass concentrations of particles are determined corresponding to the most complete burnout of carbon fuel.

Nonlinear phenomenon in laser-induced finite-amplitude acoustic waves propagating along cracks

The propagation of the longitudinal and surface waves along cracks in the plate was studied. Waves with strain up to 5×10−3 could be generated by radiation of a Q-switched laser absorbed in a layer of liquid suspended carbon particles deposited on the surface of the plate. The longitudinal and surface Rayleigh waves traveled parallel to and on the fracture surfaces, respectively, and bounced from the free surfaces of the plate. It was observed that the longitudinal echo pulses exhibited shapes, which were dependent on the magnitude of the laser excitation and, thus, on the amplitudes of the laser-generated acoustic waves. At a certain photo-excitation level, the leading tensile part of the first longitudinal echo vanished and reappeared again at higher excitation levels. This effect did not occur in the crack-free areas of the plate and was amplitude-dependent; therefore, it could be attributed to the nonlinear interaction of the longitudinal and surface Rayleigh waves with the crack.

Study of Ignition and Combustion of Two-Fraction Coal-Air Suspension

A two-fraction dust-air mixture is the simplest example of polydisperse suspensions. We aim to study the characteristics of ignition and combustion of a two-fraction suspension of carbon particles in air at different temperatures. The main characteristics of the dispersed fuel combustion are the ignition delay, burning temperature and time, and critical parameters (temperature, diameters of particles, and mass concentrations) corresponding to the fuel ignition and extinction. The high-temperature heat and mass transfer and chemical kinetics are modeled for a two-fraction particles-gas suspension (diameter of fine particles 60 мm and for that with coarse particles 120 мm) with equal mass fractions. The gas temperature is varied in the interval between 1100 K and 1500 K.

Burning of Two-Fraction Coal-Air Suspension

Two fraction dust-air mixture is a simplest case of polydisperse suspension. So the purpose of this work is to study the characteristics of ignition and combustion of a two-fraction suspension of carbon particles in air at different temperatures. The main characteristics of fuels combustion are the ignition delay, the burning temperature and time, critical parameters (temperature, the particles diameters and mass concentrations), corresponding to fuel ignition and extinction. The high temperature heat and mass transfer and chemical kinetics are modeled for two-fraction gas suspension (diameter of fine particles 60 μm and that of coarse particles 120 μm).

IGNITION AND COMBUSTION OF GAS SUSPENSION OF CARBON PARTICLES AT DIFFERENT TEMPERATURES

Physical and mathematical modeling of high-temperature heat and mass transfer and kinetics of chemical transformations of a two-fraction gas suspension of carbon particles is carried out. The characteristics of ignition and combustion of gas-suspension particles in air at different gas temperatures are determined. With a decrease in the gas temperature, the induction period of the fine fraction exceeds the induction period of the coarse fraction, and the burning temperature is lower. Critical parameters of ignition and extinction of a two-fraction gas suspension are found.

Influence of gas temperature on ignition, burning and extinction of carbon particles-gas suspension

The ignition and burning of monodisperse and two-fraction suspensions of carbon particles at gas temperature in the range 1100 ÷ 1500 K are modeled. The critical gas temperature of the suspension ignition, the particles ignition delay and burning time, the burning temperature, and the extinction parameters are determined. The data obtained are compared with burning characteristics of single particle of equal size. The ignition temperatures of the fine fraction (the particle diameter 60 μm) and the coarse one (120 μm) are practically the same. The ignition temperatures of the equivalent single particles are much higher and they differ by 100 K and more. The gas temperature is found below which the ignition delay of the fine fraction exceeds the one of the coarse fraction. It is found that, at critical ignition temperatures the burning temperature of the fine fraction is lower than that of the coarse fraction. At gas temperatures above 1250 K, the burning temperature of the fine fraction is higher. It is established that, in contrast to single particles, the temperature difference between the particles and the gas is small during gas-suspension extinction. Further oxidation of the particles occurs in the kinetic regime, so it is possible to estimate the time of their complete conversion.

Development of Redox-Active Flow Electrodes for High-Performance Capacitive Deionization.

An innovative flow electrode comprising redox-active quinones to enhance the effectiveness of water desalination using flow-electrode capacitive deionization (FCDI) is described in this study. The results show that, in addition to carbon particle contact, the presence of the aqueous hydroquinone (H2Q)/benzoquinone (Q) couple in a flowing suspension of carbon particles enhances charge transfer significantly as a result of reversible redox reactions of H2Q/Q. Ion migration through the micropores of the flow electrodes was facilitated in particular with the desalination rate significantly enhanced. The cycling behavior of the quinoid mediators in the anode flow electrode demonstrated a relatively high stability at the low pH induced, suggesting that the mediator would be suitable for long-term operation.

Endoscopic Tattoing: From Blue to Black

Introduction: Endoscopic tattooing is performed to localize a luminal deformity during surgery or repeat endoscopy. The most commonly accepted injection dye contains India Ink. However, this case demonstrates an adverse event when undiluted methylene blue is injected into the submucosa by mistake. Case Report: A 66-year-old female underwent a colonoscopy for evaluation of diarrhea. Two 10 and 20 mm polyps were seen in the ascending colon. Due to poor prep in the right colon, a polypectomy was not pursued. Since the lesions were hard to identify, two tattoos were placed 3 cm distal to each polyp (Figure 1). It was discovered that instead of Endomark (PMT Corporation, Chanhassen, MN, USA), undiluted methylene blue was injected in the submucosa (Figure 1). Eight days later a repeat colonoscopy was done to attempt polypectomy. Two deep, necrotic exudate covered ulcers were at the site of the tattoos (Figure 2). No bleeding was present (Figure 3). The polyps were successfully removed with saline injection snare polypectomy and histology revealed sessile serrated adenomas. Follow up at 6 months showed a well-healed polypectomy with methylene blue induced ulcer sites.Figure 1Figure 2Figure 3Discussion: Endoscopic tattooing is indicated to localize a luminal deformity during repeat endoscopy or surgery. The most commonly used substance is India Ink which consists of suspensions of carbon particles [1]. Other agents are much less useful compared with India Ink in regards to ease of use, efficacy, and safety [1]. Furthermore, tattoos that contain higher diluted preparations of India Ink were consistently seen at 5 months and produced no gross inflammation [2]. Even though the number of complications following endoscopic tattooing is small, it is not limited with majority related to transmural injection. Injection of methylene blue has been described to cause ulceration and necrosis during breast surgery, cochlear implantation, and laparotomy [3] [4]. However, this is the first decryption of a necrotic ulcer due to inadvertent injection in the colon. Endoscopists should be aware of this adverse event and verify the type of solution to be used for tattooing.

Solid Suspension Flow Batteries Using Earth Abundant Materials

The technical features of solid-electrode batteries (e.g., high energy density, relatively low capital cost ($/kWh)) and flow batteries (e.g., long cycle life, design flexibility) are highly complementary. It is therefore extremely desirable to integrate their advantages into a single storage device for large-scale energy storage applications where lifetime cost ($/kW-h/cycle) is an extremely important parameter. Here, we demonstrate a non-Li-based-flow battery concept that replaces the aqueous solution of redox-active molecules found in typical redox flow batteries with suspensions of hydrophilic carbon particles ("solid suspension electrodes") coated with earth-abundant redox-active metals. The solid suspension electrodes charge by depositing earth-abundant redox-active metals onto the carbon particle suspension, which are then stripped during discharge operation. The electrical contact to the solid suspension electrodes is fed through fixed redox-inert hydrophobic carbon current collectors through "contact charge transfer" mechanism. The hydrophobicity of the current collectors prevents direct plating of redox-active metals onto their surfaces. The above concept was successfully used to demonstrate several non-Li-based battery chemistries including zinc-copper, zinc-manganese oxide, zinc-bromine, and zinc-sulfur, providing a pathway for potential applications in medium and large-scale electrical energy storage.

Controllable optical transparency using an acoustic standing-wave device

In this paper, a suspended-particle device with controllable light transmittance was developed based on acoustic stimuli. Using a glass compartment and carbon particle suspension in an organic solvent, the device responded to acoustic stimulation by alignment of particles. The alignment of light-absorbing carbon particles afforded an increase in light transmittance as high as 84.5% and was controllable based on the control of the frequency and amplitude of the acoustic waves. The device also demonstrated alignment memory rendering it energy-efficient.

Transverse flowmetry of carbon particles based on photoacoustic Doppler standard deviation using an auto-correlation method

In order to measure the flow velocity of carbon particle suspension perpendicular to the receiving axis of ultrasound transducer, the standard deviation of photoacoustic Doppler frequency spectrum is used to estimate the bandwidth broadening, and the spectrum standard deviation is calculated by an auto-correlation method. A 532 nm pulsed laser with the repetition rate of 20 Hz is used as a pumping source to generate photoacoustic signal. The photoacoustic signals are detected using a focused PZT ultrasound transducer with the central frequency of 10 MHz. The suspension of carbon particles is driven by a syringe pump. The complex photoacoustic signal is calculated by Hilbert transformation from time domain signal before auto-correlation. The standard deviation of the Doppler bandwidth broadening is calculated by averaging the auto-correlation results of several individual A scans. The feasibility of the proposed method is demonstrated by measuring the spectrum standard deviation of the transversal carbon particle flow from 5.0 mm/s to 8.4 mm/s. The experimental results show that the auto-correlation result is approximately linearly distributed within the measuring range.

AN EXPERIMENTAL ANALYSIS OF S.I ENGINE PERFORMANCE WITH HHO AS A FUEL

Alternate fuel is important and it should be fossil one. Actually we spend one third of our income for our vehicle fuelling and the vehicle gives harmful decomposed materials like CO, NOx, HC, WCBSFC, etc. in the form of smoke. These materials are all affects the engine performance and pollutes the environment. Water is one of the free recourses and by applying the technique, it can be converted into hydrogen with oxygen, its chemical term is HHO and in general “Free Energy”. To avoid these drawbacks, some level of HHO is mixed with filtered air, which is after the air filter system and before the engine in taken system of the vehicle. This mixed HHO ignites releasing the extra electrons into the igniting fuel and thus the added extra energy from the HHO leads cent percent of complete burning of the fuel. HHO is popular and common gas produced from electrolysis. The outcome get by this project is that there is increasing in mileage of the vehicles up to certain percentage according to their specification & running condition of vehicle & also there is a reduction of harmful decomposed material up to certain percentage. There is increasing in the engine lubricating oil life up to certain service timing & there is also reduction in suspended carbon particles inside the engine combustion chamber. From the above description we can say that the fuel efficiency and vehicle performance are increased. The emissions of harmful and toxic gases are reduced up to some percentage. This is the safest method to give clean & healthy environment to the next generation people by installing this HHO model in all two and four wheelers vehicles.

Photoacoustic Doppler flowmetry of carbon particles flow using an autocorrelation method

In order to measure the axial flowing velocity of carbon particle suspension with particle diameter of tens of micrometers, the photoacoustic Doppler (PAD) frequency shift is calculated based on a series of individual A scans using an autocorrelation method. A 532 nm pulsed laser with repetition rate of 20 Hz is used as a pumping source to generate photoacoustic signal. The photoacoustic signals are detected using a focused piezoelectric (PZT) ultrasound transducer with central frequency of 5 MHz. The suspension of carbon particles is driven by a syringe pump. The complex photoacoustic signal is calculated by the Hilbert transformation from time-domain photoacoustic signal, and then it is autocorrelated to calculate the Doppler frequency shift. The photoacoustic Doppler frequency shift is calculated by averaging the autocorrelation results of some individual A scans. The advantage of the autocorrelation method is that the time delay in autocorrelation can be defined by user, and the requirement of high pulse repetition rate is avoided. The feasibility of the proposed autocorrelation method is preliminarily demonstrated by quantifying the motion of a carbon particle suspension with flow velocity from 5 mm/s to 60 mm/s. The experimental results show that there is an approximately linear relation between the autocorrelation result and the setting velocity.

Effect of an internal reaction on the characteristics of high-temperature heat and mass transfer of gas suspensions of carbon particles

The high-temperature heat and mass transfer of a gas suspension of carbon particles has been simulated physically and mathematically with allowance for the chemical reaction in their pores. It is established that the internal reaction leads to a significant decrease of the ignition delay times and critical parameters determining the ignition and extinction of particles of a gas suspension. The range of the initial particles sizes and mass concentrations, corresponding to the most complete burnout of carbon fuel, is found; the effect of the internal reaction on the limits of this range is analyzed. It is shown that the way of varying the mass concentration affects qualitatively the dependences of the ignition delay on the mass concentration.

Numerical and Experimental Study of Suspensions Containing Carbon Blacks Used as Conductive Additives in Composite Electrodes for Lithium Batteries

Suspensions of carbon blacks and spherical carbon particles are studied experimentally and numerically to understand the role of the particle shape on the tendency to percolation. Two commercial carbon blacks and one lab-synthesized spherical carbon are used. The percolation thresholds in suspensions are experimentally determined by two complementary methods: impedance spectroscopy and rheology. Brownian dynamics simulations are performed to explain the experimental results taking into account the fractal shape of the aggregates in the carbon blacks. The results of Brownian dynamics simulations are in good agreement with the experimental results and allow one to explain the experimental behavior of suspensions.