Microwave drying optimization and kinetic modeling of fly ash from municipal solid waste incineration

As a kind of hazardous waste, municipal solid waste incineration fly ash (MSWI FA) needs to be stored in a dry state in the process of landfill, transportation, and comprehensive utilization. Therefore, from the perspective of safety and sustainable development, it is necessary to dry as the pretreatment of MSWI FA. In this paper, MSWI FA drying experiments were carried out under different microwave power, different initial moisture content, and different particle size distribution conditions. The drying characteristics of MSWI FA were explored and the thin-layer drying kinetic model was used to explore the basic theory of the dynamics of MSWI FA drying process for the first time. The fitting analysis of the experimental data showed that the drying efficiency of MSWI FA increases gradually with the increase of microwave power and fly ash particle size, and the drying process of MSWI FA could be well represented by the Diffusion approach model (R² greater than 0.99). Through Fick's second law calculation, it was found that when the microwave power was increased from 400w to 800w, the surface diffusion coefficient increased from 1.11 × 10^-12 m²/s to 2.92 × 10^-12 m²/s, which further showed that the microwave power has a significant effect on the drying efficiency of MSWI FA.     

Optimization of the spray-drying process for developing aquasolv lignin particles using response surface methodology

Particle size and morphology are of high industrial importance due to the fact that product properties and performance can be affected by this factors. For instance, bulk properties, processability and appearance of the final product are given by particle size and shape. In this regard, the optimization of process parameters for particle development is required when targeting formulation of specific product and/or particular properties. Response surface methodology (RSM) was used to optimize the spray drying process for the development of aquasolv lignin particles with desired particle size and morphology. The inlet drying temperature X₁: 180–200 °C, atomization pressure X₂: 1.3–1.7 bar and feeding rate X₃: 65–75 mL min⁻¹ were kept as independent variables while the optimizing responses were_: Yield fine of particles with desired particle size and particle size (D₅₀). The quadratic part of the equation and statistical analysis showed substantial effect of the atomizing pressure and feeding rate on the responses and the optimized conditions validated the model. Optimum processing conditions for spray drying of aquasolv lignin were inlet temperature of 173 °C, 1.8 bar atomization pressure and 62 mL/min feeding rate. With this, desired responses of powder were 66% of yield and particle size of D₅₀ < 30 µm were obtained. The experimental values were found to be in agreement with the predicted values indicating the suitability of the model in predicting the particle size and yield of aquasolv lignin.     

The Prediction of the Emissivity and Thermal Conductivity of Powder Beds

The present study attempts to understand drying characteristics of rubber wood sawdust in a tray dryer as it is the simplest and oldest of the dryers known commercially. An increase in temperature, flow rate of the heating medium, and initial moisture content was found to increase the drying rate. However, an increase in the particle diameter and bed height was found to reduce the drying rate. The increase in drying rate with temperature and moisture content was attributed to increase in the diffusion coefficient, while the increase due to the flow rate is attributed to reduction in the external mass transfer resistance during early stages of drying while the drying rate was high. An increase in bed height as well as particle size increases the diffusion path length for moisture, which contributes to the reduction in drying rate. The experimental data were modeled using Fick's diffusion equation, and the effective diffusivity coefficient was evaluated by minimizing the error between the experimental data and the prediction using the model equation. The effective diffusion coefficient was found to increase with increase in temperature, initial moisture content, and the flow rate of the heating medium, while it was found to decrease with increase in particle size. The diffusion coefficient was not found to vary with the bed height/solid loading. The effective diffusion coefficient was found to vary within 9.1 × 10^?9to 22 × 10^?9 m²/min. The standard deviation of error between the experimental data and prediction using the model, using the estimated effective diffusivity coefficient, was found to be less than 0.07 for the entire set of data, indicating the appropriateness of the model in predicting drying kinetics.     

Volume and dislocation diffusion of iron,chromium and cobalt in CVD β-SiC

Impurity tracer diffusion of ⁵⁹Fe, ⁵¹Cr and ⁵⁷Co in CVD β-SiC has been studied in the temperature range between 973 and 1873 K. The temperature dependence of the volume diffusion coefficients of iron and chromium can be expressed by linear Arrhenius equations. The preexponential factor and the activation energy are estimated to be 8.7×10⁻¹⁵ m² s⁻¹ and 111 kJ mol⁻¹ for iron, respectively, and 9.5×10⁻¹⁵ m² s⁻¹ and 81 kJ mol⁻¹ for chromium, respectively. The diffusion coefficients of iron and chromium are much higher than those of the self-diffusion in β-SiC. Furthermore, the activation energies for the diffusion of iron and chromium are about one-tenth of those for carbon and silicon in β-SiC. Therefore, it seems that an interstitial mechanism is predominant for the diffusion of iron and chromium in β-SiC. On the other hand, the diffusion coefficient of cobalt above 1673 K is higher than that of iron, while at lower temperatures it is much lower than that of iron. The difference in the diffusion coefficients at 1173 K is more than three orders of magnitude. Thus, the temperature dependence of the diffusion coefficients of cobalt shows a strongly curved Arrhenius relation. This suggests that cobalt atoms diffuse by an interstitial mechanism at higher temperatures and by a substitutional mechanism at lower temperatures. From the deeper regions of the penetration profiles of iron, chromium and cobalt the dislocation diffusion coefficients of them have been estimated.     

Modifying the morphology and structure of graphene oxide provides high-performance LiFePO4/C/rGO composite cathode materials

In this study we synthesized LiFePO₄/carbon/reduced graphene oxide (LFP/C/rGO) composite cathode materials using a method involving sol–gel processing, spray-drying, and calcination. To improve the electrochemical performance of LFP/C, we tested graphene oxides (GOs) of various morphologies as conductive additives, including pristine GO, three-dimensional GO, and hydrothermal porous GO (HTGO). Among our samples, the cathode material prepared through spray-drying with the addition of 1 wt% of HTGO (denoted SP-LFP/C/1%rHTGO) displayed the best electrochemical performance; its discharge capacities at 0.1C, 1C, 5C, and 10C were 160.5, 151.8, 138.8, and 130.3 mA h g⁻¹, respectively. From measurements of its long-term cycling performance, the discharge capacity in the first cycle and the capacity retention after 30 cycles at 0.1C were 160.2 mA h g⁻¹ and 99.6%, respectively; at 10C, these values were 132.2 mA h g⁻¹ and 91.8%, respectively. The electronic conductivity of SP-LFP/C/1%rHTGO (6.58 × 10⁻⁵ S cm⁻¹) was higher than that of the pristine LFP/C (9.24 × 10⁻⁶ S cm⁻¹). The Li⁺ ion diffusivities (D_Li⁺) of the SP-LFP/C/1%HTGO cathode, measured using AC impedance (3.91 × 10⁻¹³ cm² s⁻¹) and cyclic voltammetry (6.66 × 10⁻¹⁰ cm² s⁻¹ for discharge), were superior to those of the LFP/C cathode (9.31 × 10⁻¹⁵ cm² s⁻¹ and 1.79 × 10⁻¹⁰ cm² s⁻¹ for discharge, respectively). Galvanostatic intermittent titration revealed that the value of D_Li⁺ was located in a reasonable range from 1 × 10⁻¹⁰ to 1 × 10⁻¹⁷ cm² s⁻¹; its value dropped to its lowest point when the state of charge was close to 50%. Thus, the use of spray-drying and the addition of conductive HTGO (having a 3D wrinkled morphology and interconnected pore structure) can enhance the electronic conductivity and Li⁺ ion diffusivity of LFP/C cathode materials, thereby improving the electrochemical performance significantly.     

The effect of polymeric wall on the permeability of drug-loaded nanocapsules

The aim of this work was to establish a quantitative correlation between the drug permeability and the polymer concentration in the nanocapsules. Indomethacin ethyl ester-loaded nanoemulsion and nanocapsules containing poly(epsilon-caprolactone) at different concentrations (0, 2, 4, 6, 8 and 10 mg/mL) presented drug loading between 0.981 and 1.005 mg/mL, pH values from 5.0 to 5.4, particle sizes between 232 and 261 nm, polydispersity lower than 0.24 and zeta potentials from − 8.54 mV to − 11.86 mV. An alkaline hydrolysis of indomethacin ethyl ester carried out at the particle/water interface was used to simulate a sink condition of release. The number of particles in each suspension was estimated. The calculated values ranged from 5.84 × 10¹² to 6.60 × 10¹² particles cm^− 3, showing similar concentration of particles in the formulations. The diffusion was proposed as the main mechanism of the indomethacin ester release after fitting the data to the Higuchi model. Applying the Fick's first law, the calculated indomethacin ester fluxes (J) decreased from 2.20 × 10^− 7 to 1.43 × 10^− 7 mg cm^− 2 min^− 1. Then, the drug relative permeability decreased according to the increase in the polymer concentration fitting a power law.     

Temperature influence on the voltage-controlled diffractive property of Mn-doped potassium sodium tantalate niobate crystal

We report the temperature influence on the voltage-controlled diffractive property of Mn-doped potassium sodium tantalate niobate crystal. The crystal was grown by the top seeded solution growth method. Its quadratic electro-optic coefficients achieved as high as R₁₁ = 3.50 × 10⁻¹⁵ m²/V² and R₁₂ = −0.44 × 10⁻¹⁵ m²/V² near the Curie temperature, while they declined with the increasing temperature. The external electric field which correspond to the maximum diffraction efficiency of photorefractive grating moved from 166 V/mm to 512 V/mm as the temperature increased from 25 °C to 32.5 °C. The maximum diffraction efficiencies all reached the maximum value of 60% at different temperatures. The results were discussed and compared with the theoretical equations.     

Dry dense medium separation of iron ore using a gas–solid fluidized bed

The dry dense medium separation of iron ore based on floating and sinking of ore particles in a gas–solid fluidized bed was investigated using zircon sand as the fluidized medium. The float-sink of ore particles with mean size D_ave = 23.6 mm was investigated as the fluidizing air velocity and the float-sink time were varied. It was found that gangue with density less than 2850 kg/m³ which float is able to be separated from valuable ore with density greater than 2850 km/m³ which sink. The set point (density where half the particles float and half the particles sink) decreases with increasing the air velocity, and that the float-sink separation is completed within 2 min. The influence of different sized ore particles in the float-sink experiments was also investigated. As a result, the iron ore with D_ave ? 17.6 mm are successfully separated. As D_ave decreases below 17.6 mm, the ore particles with density near the set point tend to scatter in the fluidized bed without floating or sinking, resulting in separation efficiency which decreases with decreasing D_ave. This indicates that the size of the ore particles is one of the major factors to achieve high separation efficiency.     

How to use electrodeless drift chambers in experiments at accelerators

Several types of wide-gap electrodeless drift chambers, including those with dimensions 1×1 m², have been tested at accelerator beams. The chambers work with high efficiency (>99%), good spatial resolution (σ = 0.2−0.4 mm) and good linearity at flux rates up to 2×10⁵ particles⁻¹ per wire in spill, which corresponds to 3×10⁶ particles/s m² on colliders.It is shown that at the proper mode of operation beam intensity oscillations within the range of up to 4×10⁵ particles/spill per wire do not affect the chamber efficiency.     

Development of an inconel self powered neutron detector for in-core reactor monitoring

The paper describes the development and testing of an Inconel600 (2 mm diameter×21 cm long) self-powered neutron detector for in-core neutron monitoring. The detector has 3.5 mm overall diameter and 22 cm length and is integrally coupled to a 12 m long mineral insulated cable. The performance of the detector was compared with cobalt and platinum detectors of similar dimensions. Gamma sensitivity measurements performed at the ⁶⁰Co irradiation facility in 14 MR/h gamma field showed values of −4.4×10⁻¹⁸ A/R/h/cm (−9.3×10⁻²⁴ A/γ/cm²-s/cm), −5.2×10⁻¹⁸ A/R/h/cm (−1.133×10⁻²³ A/γ/cm²-s/cm) and 34×10⁻¹⁸ A/R/h/cm (7.14×10⁻²³ A/γ/cm²-s/cm) for the Inconel, Co and Pt detectors, respectively. The detectors together with a miniature gamma ion chamber and fission chamber were tested in the in-core Apsara Swimming Pool type reactor. The ion chambers were used to estimate the neutron and gamma fields. With an effective neutron cross-section of 4b, the Inconel detector has a total sensitivity of 6×10⁻²³ A/nv/cm while the corresponding sensitivities for the platinum and cobalt detectors were 1.69×10⁻²² and 2.64×10⁻²² A/nv/cm. The linearity of the detector responses at power levels ranging from 100 to 200 kW was within ±5%. The response of the detectors to reactor scram showed that the prompt response of the Inconel detector was 0.95 while it was 0.7 and 0.95 for the platinum and cobalt self-powered detectors, respectively. The detector was also installed in the horizontal flux unit of 540 MW Pressurised Heavy Water Reactor (PHWR). The neutron flux at the detector location was calculated by Triveni code. The detector response was measured from 0.02% to 0.07% of full power and showed good correlation between power level and detector signals. Long-term tests and the dynamic response of the detector to shut down in PHWR are in progress.     

Numerical simulation for parameter optimization of silicon purification by electron beam melting

In this paper a mathematical model is developed to investigate the removal of volatile impurities in molten silicon by electron beam melting (EBM) with a high efficiency and low energy consumption. The temperature distribution of molten silicon is obtained using the commercial software FLUENT. Based on the temperature distribution, the vaporization behaviors of phosphorus and silicon are investigated by Langmiur's vaporization theory. The results show that the evaporation rate of silicon during EBM increases exponentially with the increase of beam power, while, it decreases with the increase of scanning radius. The optimal parameters are discussed from the aspect of efficiency and energy saving. The energy consumption decreases with the decrease of scanning radius and with the increase of the beam power. The optimum values are consider to be with a scanning radius of 0.0339 m and a beam power of 23.4 kW for 0.5 kg silicon when phosphorus is removed from 1.44 × 10⁻² to 1 × 10⁻⁵ (wt.%).     

Nucleate boiling heat transfer coefficients of HFO1234yf on various enhanced surfaces

In this study, nucleate boiling heat transfer coefficients (HTCs) of HFO1234yf HFC134a are measured on a flat plain, Turbo-B, Turbo-C, and Thermoexcel-E surfaces. All data are taken at the liquid pool temperature of 7 °C on small flat horizontal square copper plates (9.53 mm × 9.53 mm) at heat fluxes from 10 kW m⁻² to 200 kW m⁻² with an interval of 10 kW m⁻². Test results show that nucleate boiling HTCs of HFO1234yf on all four surfaces are similar to those of HFC134a at all heat fluxes tested in this study. At heat fluxes below 150 kW m⁻², Thermoexcel-E surface shows the highest heat transfer performance and hence is the best surface for the manufacture of the evaporators in refrigeration and air-conditioning equipment. On the other hand, at high heat fluxes above 150 kW m⁻², Turbo-B and Turbo-C show better heat transfer performance than Thermoexcel-E and hence are good for electronic cooling applications. Overall, HFO1234yf is a good long term candidate with excellent environmental properties to replace successfully HFC134a from the view point of pool boiling heat transfer. Hence HFO1234yf can be readily applied to the conventional evaporators designed for HFC134a.     

Tribological performance of DLC coatings deposited by ion beam deposition under dry friction and oil lubricated conditions

Understanding the reaction between lubricant additives and diamond-like carbon coatings is imperative for the improvement of the friction and wear properties of mechanical parts with diamond-like carbon coatings. Diamond-like carbon coatings were deposited with ion beam deposition and the influence of lubricant additives on the friction coefficients and wear rates of diamond-like carbon coatings under the lubricated conditions was studied. It was revealed that the wear rates of diamond-like carbon coatings under unlubricated conditions are 1.5 × 10⁻¹⁴ m³/(Nm) while they are decreased to 3 × 10⁻¹⁷ m³/(Nm) to 1.7 × 10⁻¹⁶ m³/(Nm) when lubricated by PAO-4 base oil with three additives. The addition of molybdenum dithiocarbamate in PAO-4 base oil decreases the friction coefficients of diamond-like carbon coatings to 0.07, but increases the wear rate of diamond-like carbon coatings. The addition of zinc dialkyl dithiophosphate to PAO-4 can slightly decrease the friction coefficient of diamond-like carbon coatings and improve the wear resistance of diamond-like carbon coatings. The addition of amine sulfuric-phosphate diester in PAO-4 can greatly decrease the wear rate of diamond-like carbon coatings to 3 × 10⁻¹⁷ m³/(Nm) but has a negligible effect on the friction coefficients of diamond-like carbon coatings.     

CFD numerical simulation on diffusion and distribution of diesel exhaust particulates in coal mine heading face

Diesel equipment used in underground production and transportation will produce a large amount of diesel particulate matter (DPM), which seriously pollutes the fresh air in underground and endangers the life and health of miners. In order to study the diffusion and distribution of DPM, this paper based on CFD numerical simulation technology, carries out numerical simulation of airflow and DPM field in heading face. The results show that from 15 s to 60 s, DPM continuously accumulates in the blind zone of the airflow and on both sides of the monorail locomotive, with the DPM concentration greater than 1.2 × 10⁻⁷ kg/m³. At this time, the DPM cloud is 60 m in the horizontal direction, and shows a distribution characteristic of high in the middle and low on both sides. When T = 90 s, part of DPM diffuses to the roadway exit. At this time, in the entire roadway, starting from a section of 23 m away from the heading face, the DPM concentration sharply increases, reaching a peak of 2.91 × 10^-7 kg/m³ at 33 m. Then it begins to decline slowly. The research results are of great significance to clean production in mines.     

Measurement of absorbed dose by 7-GeV bremsstrahlung in a PMMA phantom

High-energy electron storage rings generate energetic bremsstrahlung photons through radiative interaction of the particle beam with the residual gas molecules and other components inside the storage ring. At synchrotron radiation facilities, where beamlines are channeled out of the storage ring, a continuous bremsstrahlung spectrum, with a maximum energy of the stored particle beam, will be present. At the advanced photon source (APS), where the stored beam energy is 7 GeV, bremsstrahlung generated in the straight sections of the insertion device beamlines, which are a total of 15.38 m in length, can be significant. The contribution from each bremsstrahlung interaction adds up to produce a narrow mono-directional bremsstrahlung beam that comes down through the insertion device beamlines. The resulting absorbed dose distributions by this radiation in a 300 mm×300 mm×300 mm tissue substitute cube phantom were measured with LiF:Mg,Ti (TLD-700) thermoluminescent dosemeters. The normalized absorbed dose, in a cross-sectional area of 100 mm² at a depth of 150 mm of the PMMA phantom, was measured as 3.3×10⁶ mGy h⁻¹W⁻¹ for 7-GeV bremsstrahlung spectrum.     

Toward the High-Performance Lithium Primary Batteries by Chemically Modified Fluorinate Carbon with δ-MnO2

Li/CF_x battery is one of the most promising lithium primary batteries (LPBs) which yields the highest energy density but with poor rate capability. This Achilles'’ heel hinders the large-scale applications of Li/CF_x batteries. This work first reports a facile chemical modification method of CF_x with δ-MnO₂. Having benefited from the chemical bonding, the electrochemical performance at high-rate discharge is remarkably enhanced without compromising the specific capacity. The coin cells exhibit an energy density of 1.94 × 10³ Wh kg⁻¹ at 0.2 C, which is approaching the theoretical energy density of commercial fluorinated graphite (2.07 × 10³ Wh kg⁻¹). A power density of 5.49 × 10⁴ W kg⁻¹ at 40 C associated with an energy density of 4.39 × 10² Wh kg⁻¹, which is among the highest value of Li/CF_x batteries, are obtained. Besides, the punch batteries achieve an ultrahigh power density of 4.39 × 10⁴ W kg⁻¹ with an energy density of 7.60 × 10² Wh kg⁻¹ at 30 C. The intrinsic reasons for this outstanding electrochemical performance, which are known as the fast Li⁺ diffusion kinetics guided by thin δ-MnO₂ flakes and the low formation energy barrier caused by chemical bonding, are explored by the galvanostatic intermittent titration technique (GITT) and theoretical calculations.     

Estimation of diffusion parameters in fluidized bed drying

The present work is an attempt to assess the drying kinetics of green pepper in a fluidized bed in a temperature range of 65–105 °C. The drying kinetics is modeled using several semi empirical models to estimate the kinetic parameters. Although the semi empirical model could fit the experimental data well within acceptable experimental error limits, the two parameter models such as Henderson Pabis model and Page Model are identified to predict the drying kinetics with lesser error. The kinetic parameter (k) is found to increase with the temperature for all the models. The activation energy (E) estimated using Arrhenius equation is found to be 30.3 kJ/mol, while the Arrhenius constant (k_o) is found to be 0.09 s^?1. The effective diffusivity coefficient is evaluated using Fick’s diffusion equation which is found increase with increase in temperature of the heating medium and to vary from 1.95 × 10^?11 to 7 × 10^?11 m²/s.     

Battery in the form of a cement-matrix composite

Reported here is a battery in the form of a cement-matrix composite, with cement paste as the matrix, the pore solution in cement as the electrolyte, zinc particles dispersed in the matrix as the anode, manganese dioxide particles dispersed in the matrix as the cathode, and carbon black dispersed in the matrix as the conductive additive in both anode and cathode regions. The electrolyte is continuous throughout the battery, which consists of successively cast and co-cured anode, electrolyte and cathode layers. The anode layer (4 mm thick) comprises cement and zinc particles. The cathode layer (8 mm thick) comprises cement and manganese dioxide particles. The electrolyte layer (2 mm thick) is cement with an embedded piece of tissue paper for drying shrinkage control. The battery attained open-circuit voltage up to 0.72 V, current up to 120 μA (current density up to 3.8 μA/cm²), power output up to 1.4 μW/cm², capacity up to 0.2 mA h, and fraction of zinc consumed up to 5 × 10^?5.     

Electrical and thermal conductivity in Mg–5Sn Alloy at different aging status

The electrical conductivity, thermal conductivity and its relationship with the microstructure in Mg–5Sn alloy aged at 513 K for different aging times were investigated systematically in this paper. The results show that the electrical conductivity and thermal conductivity obviously increase with the increasing aging time, and its values increase from 10.25 × 10⁶ S·m^− 1 to 13.7 × 10⁶ S·m^− 1, 87.5 W·m^− 1·K^− 1 to 122 W·m^− 1·K^− 1 after aging treatment for 120 h, respectively. Meanwhile, it is found that there exist quite different relationships between unit cell volume and thermal conductivity in early and later aging stages.     

Structure,spectroscopic properties and laser performance of Nd:YNbO4 at 1066 nm

We have demonstrated continuous wave (CW) laser operation of Nd:YNbO₄ crystal at 1066 nm for the first time. A maximum output power of 1.12 W with the incident power of 5.0 W is successfully achieved corresponding to an optical-to-optical conversion efficiency of 22.4% and a slope efficiency of 24.0%. The large absorption cross section (8.7 × 10⁻²⁰ cm²) and wide absorption band (6 nm) at around 808 nm indicates the good pumping efficiency by laser diodes (LD). The small emission cross section (29 × 10⁻²⁰ cm²) and relative long lifetime of the ⁴F_3/2 → ⁴I_11/2 transition indicates good energy storage capacity of Nd:YNbO₄. Moreover, the raw materials of Nd:YNbO₄ are stable, thus, it can grow high-quality and large-size by Czochralski (CZ) method. Therefore the Nd:YNbO₄ crystal is a potentially new laser material suitable for LD pumping.