Mass Of Column Research Articles

Mass and heat transfer behavior of a bubble column fitted with horizontal spiral tubes in bubbly-flow regime

Slurry bubble columns are commonly used for gas-liquid-solid diffusion-controlled reactions. However, they have some shortcomings, such as the high cost of separating the final product from the catalyst particles. This study proposes the use of spiral tubes as catalyst support to address these shortcomings. The liquid-solid mass transfer behavior of spiral tubes under different conditions of gas superficial velocity, spiral tube diameter, and pitch was studied using the electrochemical technique. The mass transfer coefficient was found to increase with increasing superficial gas velocity but decrease with increasing tube diameter and pitch. The data were correlated by a dimensionless equation suitable for the design and scale-up of the reactor. In addition to serving as catalyst support, the internal surface of the spiral tube can be used as a supplementary built-in cooler in conjunction with a cooling jacket for exothermic reactions. This is beneficial for catalytic reactions and biochemical reactions, which are prone to catalyst deactivation and thermal degradation, respectively. A study of the mass transfer behavior of a bubble column fitted with multi-spiral tubes revealed a deviation from the single spiral tube behavior by an amount ranging from 10% to 20%, depending on the operating conditions. Calculation of the ratio between the volumetric mass transfer coefficient and the specific energy consumption (performance indicator for the reactor under different conditions) revealed that the reactor has a high energy utilization efficiency.

Estimating Unsaturated Hydraulic Conductivity in Unsaturated Soil Using Soil Moisture Sensors

Unsaturated hydraulic conductivity (K) is a measurement of soil water-retaining ability in unsaturated soil. The unsaturated hydraulic properties are necessary to predict the movement of water in unsaturated soil. The current study aims to create an alternative experimental device to estimate theKusing soil moisturesensors. The experimental set up was designed and fabricated in order to measure the volumetric water content using GS3 (Campbell) sensors at different heights. The data obtained from the sensors was validated using mass of moist sand column measured from electronic balance.TheKwas estimated with the help of retention and conductivity functions. The primary materials used in the study were solute-free water and sand. It was found that the reading from the sensors was in good match with the reading of the volumetric water content calculated from the mass of water in the sand column with a root mean square error of 0.0091. Soil water retention curve and hydraulic conductivity were plotted using Peters-Durner-Iden (PDI) model.The results were compared to the van Genuchten function. TheKprediction wasinitially equivalentfor both models, but the lateroverpredicts the falling rate of hydraulic conductivity with the increasing soil matric suction before underpredict after 200 cm matric suction on a sandy soil.PDI function was able to extrapolate the hydraulic conductivity film flow region of sandy soil.

Performance characteristics assessment of hollow fiber membrane-based liquid desiccant dehumidifier for drying application

• Proposed novel integral technique based analytical model to assess HFLDD performance. • Analyzed the influence of inlet and design parameters on HFLDD performance. • Effect of Le and St numbers across and along the HFLDD is evaluated. • Case study on conventional/desiccant dryer performance is analyzed in humid climate. • Desiccant dryer found to be best alternative for humid climatic conditions. In the present study, a novel integral technique based two-point boundary value problem is developed using the simplified polynomial equations to assess the hollow fiber membrane-based liquid desiccant dehumidifier performance for drying application. The developed numerical technique is validated with the experimental data available in the literature and observed a maximum deviation of ± 9.7%. The liquid desiccant chosen is lithium chloride. By considering thermal and moisture effectiveness as performance parameters and choosing the air inlet temperature, air specific humidity, desiccant temperature, and liquid to gas ratio as input parameters, the influence of Lewis number and Stanton number on dehumidifier performance is analyzed. The performance analysis concluded that a high liquid to gas ratio, desiccant temperature, and specific humidity enhance the dehumidifier performance. Further, the variation of performance parameters along the length and thermal mass of the membrane column is also assessed. Moreover, a case study on conventional and desiccant dryers performance in humid climates is assessed and observed that the desiccant dryer is the best alternative compared to the conventional dryer. In addition, for the given operating range and inlet condition, the maximum possible vapour absorption rate (δ VAR ) and energy exchange for the conventional dryer is found to be 93 g/hr and 0.8 kW, whereas, for the desiccant dryer, it is 164 g/hr, and 1.4kW respectively.

Study of the Overflow Transport of the Nordic Sea

Changes in the climate system over recent decades have had profound impacts on the mean state and variability of ocean circulation, while the Nordic Sea overflow has remained stable in volume transport during the last two decades. The changes of the overflow flux depend on the pressure difference at the depth of the overflow outlet on both sides of the Greenland-Scotland Ridge (GSR). Combining satellite altimeter data and the reanalysis hydrological data, the analysis found that the barotropic pressure difference and baroclinic pressure difference on both sides of the GSR had a good negative correlation from 1993 to 2015. Both are caused by changes in the properties of the upper water, and the total pressure difference has no trend change. The weakening of deep convection can only change the temperature and salt structure of the Nordic Sea, but cannot reduce the mass of the water column. Therefore, the stable pressure difference drives a stable overflow. The overflow water storage in the Nordic Sea is decreasing, which may be caused by the reduction of local overflow water production and the constant overflow flux. When the upper interface of the overflow water body in the Nordic Sea is close to or below the outlet depth, the overflow is likely to greatly slow down or even experience a hiatus in the future, which deserves more attention.

Effect of genotype on the development pattern of muscles and muscle groups in steers at the age of 18 months

The development patterns of carcass muscles were studied on Simmental and Black-Spotted steers and their hybrids of the 1st generation. At the age of 18 months, a control slaughter of 3 steers of different genotypes was carried out: Group I - purebred Simmental steers; Group II - hybrids of ½ Simmentals x ½ Red Steppe steers; Group III - hybrids of ½ Simmentals x ½ Black-Spotted steers. To study the muscle groups and individual muscles development according to anatomical regions, the left half-carcasses were prepared, taking into account the methodological instructions, and to facilitate the analysis of the material, the muscles were grouped according to the joints associated with them and the topographic location, using the generally accepted scheme. The muscles development was studied on the basis of the absolute mass indices of individual muscles and muscle groups. It was established that steers of Group III had the following advantages over the animals of the same age in Groups I and II: in the total muscle mass of the spinal column the advantage was 217-772 g (1.43 - 18.30%), in the total muscle mass of the shoulder girdle - 1.45-0.51 kg (9.78-3.51 %), the thoracic limb - 231-660g (14.37-41.04%), the pelvic limb - 3.16-1.11 kg (9.78-3.45%) and in general for the entire half-carcass of the recorded muscles - 6.62-2.33 kg (9.79-3.44 %).

Steam cavity and explosion intensity of molten copper column interaction with water

The steam explosion is one of the most serious accidents in the metallurgical industry. In this paper, an experimental study on the interaction of molten copper column with cooling water was carried out using high-speed camera and transient pressure measurement system. The effects of temperature, falling height, diameter and mass of molten copper column on the interaction were investigated. The steam cavity phenomenon was observed in the interaction and the percentage of steam cavity volume affects the probability of fragmentation of molten copper column. The maximum percentage of steam cavity volume increases firstly and then decreases with the increase of temperature and falling height. It increases with the increase of diameter of molten copper column, but the mass has a weak effect. The pressure wave generated by the interaction of molten copper column with cooling water gradually increases with an increase in the temperature of molten copper column. The energy conversion rate in the interaction of molten copper column with cooling water was calculated. The rate of energy conversion from the thermal energy of molten copper column to the energy of pressure wave is low because most of the thermal energy is dissipated into the cooling water by heat transfer.

Taming the Janssen effect

We investigate both experimentally and theoretically the apparent mass of a ferromagnetic granular assembly filling a cylindrical container and submitted to a magnetic fieldB, aligned vertically along the silo. We show that the mass of the ferromagnetic granular column depends strongly on the applied magnetic field. Notably, our measurements deviate strongly from the exponential saturation of the measured mass as a function of the true mass of the grain packing, as predicted by Janssen [H.A. Janssen, Vereins Eutscher Ingenieure Zeitschrift, 1045 (1895)]. In particular, the measured mass of tall columns decreases systematically as the amplitude of the magnetic field increases. We rationalize our experimental findings by considering the induced magnetic dipole-dipole interactions within the whole packing. We show the emergence of a global magnetic radial force along the walls of the silos, fully determined by the external magnetic field. The resulting tunable frictional interactions allows a full control of the effective mass of the ferromagnetic granular column.

Influence of steer genotypes on the features of muscle development in the postnatal period of ontogenesis

The study of the carcass muscles development was carried out on Simmental and Kazakh White-Headed steers and their first generation hybrids. At the age of 18 months, the control slaughter of 3 steers of different genotypes was carried out: I - Simmental, II - Kazakh White-Headed, III - 1/2 Kazakh White-Headed x 1/2 Simmental. To study the development of muscle groups and individual muscles by anatomical regions, the left half-carcasses were prepared, taking into account the methodical instructions. To facilitate the analysis of the material, the muscles were grouped according to the relevant joints and the topographic location by the generally accepted pattern. The muscles development was studied using the data on the absolute mass of individual muscles and muscle groups. It was established that the steers of group III surpassed those of groups I and II in the total muscle mass of the spinal column, which was 1.28-0.45 kg (10.85-3.56%), the total muscle mass of the shoulder girdle - 1.45-0.51 kg (9.78-3.51%), thoracic limb - 0.72-0.25 kg (9.77-3.43%), pelvic limb - 3.16-1.11 kg (9.78-3.45%) and, in general, throughout the half-carcass of the muscles considered - 6.62-2.33 kg (9.79-3.44%).

Finite Element Analysis (FEA) Based Frequency Optimization of Vertical Storage Column

The ethanol containing vertical storage column is typically a leak proof tank which is used to store the liquid and fine powder. To exploit the storing capability, these columns are generally precise high normally above 27meters with a circular cross section. The task arranged is that the agitator and the vertical pole are necessary to be on the equal podium. Due to this the pole is predisposed to vibrations from the Campaigner. This was needed to optimize the natural frequency of the column. Stiffeners /Support are fond of to the column plate to reinforce the column counter to pressure force, to minimize the vibrations of the plate and to become rigid plate against buckling. Stiffeners must be set apart at some suitable positioning so that plate stress is low than permissible stress. If column panel tallness or breadth is less than acceptable plate span then according to assumption column doesn’t requires stiffeners/support. Though if column lifted or handles in one piece then, some stiffening may be required to keep column shape. Rise the stiffness by growing stiffeners/supports leads to load increase so no actual variance in rate of recurrence. By reducing mass of column and that can be possible only by selecting proper material. The objective of entire effort is to design of the vertical column in such a way that the natural frequency of the column can be optimized. As number of supports (horizontal) are increasing the natural frequency of column is also increasing, but at same time weight is also increased. So in order to optimize design the weight of column provided by support must be reduced. After optimize the structure of support and carrying out pre stressed modal analysis the targeted natural frequencies (>16 Hz) is obtained in the structure.

Analytical and numerical calculation of the critical buckling load in compound columns

ABSTRACT This study represents investigation of the critical buckling load in columns, which consist of two different materials for case of (fixed–free) loading in order to choose the suitable compound ratio. The investigation is done with two methods: analytical method through suggested equation for calculation of equivalent modulus of elasticity and numerical finite-element method with ANSYS APDL 17.2. The analytical and numerical results showed excellent agreement with each other because of the qualification of the suggested equation of the equivalent modulus of elasticity for the compound column. The critical buckling load is sensitive to the difference between the modulus of elasticity for the two different materials of the compound column, which also affects the ratio of the critical buckling load to the mass of the compound column.

CFD Simulations of the Propagation of Free-Surface Waves Past Two Side-By-Side Fixed Squares with a Narrow Gap

Two-dimensional computational fluid dynamics (CFD) simulations are carried out to investigate the gap resonance phenomenon that occurs when free-surface waves travel past twin squares in tandem. The volume of fluid method is used to capture the free surface. Validation studies of the present numerical model are conducted for different incident wave frequencies. The numerical results agree well with the published experimental data in terms of the free surface elevations in the gap. The hydrodynamic characteristics of the water column in the gap are investigated at different incident wave frequencies and gap widths. It is found that the free surface elevation in the gap increases and then decreases with the increasing incident wave frequency. The horizontal force on the weather side square structure (the structure in front of the gap) reaches the peak value at a larger frequency than the gap resonance frequency, whereas the variation of the horizontal force on the lee side structure (the structure behind the gap) is in-phase with the free surface elevation in the gap. Moreover, the added mass of the water column in the gap increases with the increasing gap width, which results in the decrease of resonance amplitude and frequency in the gap. However, this does not necessarily reduce the peak value of the horizontal forces on the structures.

An efficient numerical model for hydrodynamic added mass of immersed column with arbitrary cross - Section

Abstract The assessment of earthquake-induced hydrodynamic added mass is critical in the seismic design of structures supported by immersed columns. This paper developed an efficient potential-based numerical model to determine the hydrodynamic added mass for immersed column with arbitrary cross - section. General formulations of the hydrodynamic added mass for a column with general cross - section under horizontal earthquake were derived. The accuracy of the developed model for immersed columns was validated analytically and experimentally. The developed model was then applied to evaluate the hydrodynamic added mass of an immersed column with dumbbell cross - section. The hydrodynamic added mass of the example dumbbell column along various earthquake directions was determined and the directional-dependent added mass was expressed as an analytical function of the added mass along the major and minor axes of the column and the earthquake direction. The frequency- and time-domain seismic responses of the example dumbbell column were finally computed using both fluid-structure interaction (FSI) model and the developed hydrodynamic added mass model. The good agreement between seismic responses from the FSI and developed added mass model confirmed the high accuracy and efficiency of the developed model for the hydrodynamic added mass of immersed columns with arbitrary cross - section under earthquakes.

A two-layer numerical model for simulating the frontal plowing phenomenon of flow-like landslides

Many flow-like landslides entrain material from their paths during motion. At the flow front and along the lateral margins the sliding mass can plow into the path material pushing or entraining the existing soil. Although plowing can be a dominant mechanism for landslide mobility, little attention has been paid to this phenomenon in comparison with other entraining mechanism such as basal scouring. Therefore, establishing a suitable mathematical description is still a challenge. In this paper, a two-layer finite difference model is proposed to simulate frontal plowing. The frontal erodible mass and the sliding mass are simplified as two separate layers based on the assumption that they are immiscible in their propagation processes. The interaction (i.e., thrusting and shear) between the two layers is simulated by the normal force and shear force acting on the two-layer interface. The governing equations for the two-layer model are deduced from the mass and momentum conservations of a soil column and transformed into a finite difference form for numerical solving. Then the proposed model is tested in the back analysis of the Ximiaodian landslide which is a typical loess flow-like landslide located at the south bank of the Jing River, China. The modeling results show that frontal plowing has significant influence on the propagation of this landslide, especially on the final topography of the deposit. Without considering this effect, the thickness of the final deposit tends to be underestimated, while the propagation duration, area and distance are likely to be overestimated. The proposed model can provide more accurate and reliable simulations for rapid flow-like landslides with frontal plowing phenomenon.

Retrieval of the water ice column and physical properties of water-ice clouds in the martian atmosphere using the OMEGA imaging spectrometer

Using spectral images recorded by the OMEGA instrument on Mars Express (Observatoire pour la Minéralogie, l'Eau, les Glaces et l'Activité), we are able to derive physical properties of aerosols in water-ice clouds on Mars for a distribution of pixels over an observed cloud formation. These properties, mean effective radius, reff, and optical depth (at 0.67 μm), τi, were used to estimate the water ice-column (WIC), and we found an empirical relationship between the WIC and an ice cloud index (ICI). The overall mean of retrieved reff is ∼2.2 μm, with a standard deviation of 0.8 μm, and cloud formations with reff between 4.4 and 5.4 μm are observed. The optical depth varies between 0.2 and 2.0. The OMEGA spectra are primarily sensitive to water ice mass due to absorption, and we find that the ICI, very easy to compute, is a good proxy for the mass of the water-ice column (WIC) along the optical line of sight. Our retrieval of physical properties is limited in time (to before 2010) by the exhaustion of coolant for one of the OMEGA channels, and in space (to equatorial observations between 140∘W and 90∘E) by the availability of surface albedo measurements. However, we used the ICI to compute WIC values for the entire OMEGA data set, which has near-global coverage for Mars years 26–32, and we present a climatology of the WIC derived from the OMEGA data, which features enhancements on the order of 1.2–1.6 pr. μm over the aphelion cloud belt, and 1.5–2.5 pr. μm over the polar hoods. The data set analyzed is for observations between 140°W and 90°E, and between 35∘S and 35∘N. No restriction is placed on season, but the majority of cloudy observations were during the aphelion period from Ls 35∘ to 135∘. This work was motivated by the ability of the OMEGA instrument to observe the distribution of water-ice cloud physical properties, and by the availability of new a priori data sets, especially multi-spectral, aerosol-free surface albedo retrieved from a subset of the OMEGA data featuring a cloud-free sky. The main limitations of the retrieval algorithm are linked to the uncertainties on surface albedo, the dust opacity, and the quantity of water-ice suspended in the atmosphere, which can lead to spectral fits with lower accuracy or unrealistic results. We present distributions of each retrieved parameter, goodness of fit, ICI, and cloud mass, and our investigation of relationships between each parameter. Our approach was to maximize the amount of data analyzed, apply stringent data quality cuts and take a statistical approach to interpretation.

Transient liquid leakage during plunger lifting process in gas wells

Plunger lift is an economical method to solve the liquid loading problem in wells. Following our previous research (Zhao et al., 2018), which focused on the steady-state process of liquid leakage during lifting, the transient variations of plunger velocity, liquid leakage and stress conditions during plunger lifting process are investigated theoretically and experimentally in this paper. Based on the force analysis and finite difference method, the transient physical model for the mass and gas volume fraction of gas-liquid column above plunger is proposed. Combining the similarity experiments and infrared measuring technology, the proposed transient model is verified quantitatively with the relative deviation less than ±10%. The results show that both the liquid leakage and the gas volume fraction of gas-liquid column above plunger cannot be neglected during plunger lifting. The transient change rules of lifting differential pressure, plunger velocity, gas volume fraction of gas-liquid column and liquid leakage flow rate during lifting process are obtained. The influences of liquid loading condition and gas production rate on transient plunger lifting process are discussed. Through the dimensionless analysis, a dimensionless correlation for transient gas volume fraction of gas-liquid column is developed.

Relationship between pressure variations at the ocean bottom and the acceleration of its motion during a submarine earthquake

The data provided by ten DONET deep-sea observatories, that on March 11, 2011, registered the Great East Japan Earthquake and tsunami, were used for investigation of the relationship between variations of the ocean bottom pressure and three-component accelerograms. Methods of cross-spectral analysis revealed the existence of a frequency range of “forced oscillations,” within which pressure variations are proportional to the vertical component of the acceleration. This proportionality is manifested by the magnitude-squared coherence (MSC) being close to unity and a phase lag (PL) practically equal to zero. The spectral analysis method showed the proportionality coefficient to be equal the mass of a water column of unit area at the installation point of the observatory or, approximately, to the product of the water density and the ocean depth. The observed boundaries of the frequency range of “forced oscillations” are revealed to correspond to the theoretical frequency values confining the manifestation of surface gravity and acoustic waves in pressure variations near the ocean bottom. The hypothesis is put forward that the small deviations of MSC from unity and of PL from zero observed by a number of stations within the range of “forced oscillations” are due to the contribution of horizontal movements of nearby submarine slopes. A theoretical analysis has been performed of the problem of forced oscillations of a water layer in a basin of varying depth. A formula is obtained that relates pressure variations at the ocean bottom to acceleration components of the bottom motion and the bottom slope. The pressure in the region of forced oscillations is shown to decrease exponentially with the distance from the moving segment of the ocean bed, so pressure variations, originating from movements of the bottom, are registered effectively by a gauge at the ocean bottom only within a radius less than 1–2 ocean depths. A cross-spectral analysis of pressure variations and of three-component accelerograms confirmed the hypothesis concerning the contribution of horizontal movements of nearby submarine slopes to pressure variations.

Experimental study on the dynamic properties of the dual-chamber solid and liquid mixture vibration isolator

The dual-chamber solid and liquid mixture (SALiM) isolator exhibits multiple stiffness and damping properties with various parameters. As a passive isolation device, the dual-chamber SALiM isolator can also obtain a variable stiffness property by substituting the valve with an active throttle device. Before that, the dynamic properties of the isolator need to be further investigated. Sine sweep tests under different valve openings were implemented to analyze the frequency response characteristics of the system. Two hydro pressure sensors were added into the two chambers to record the pressure signals, with which the equivalent stiffness, equivalent damping, fluid damping, and equivalent mass of the liquid column were identified. Based on the test results, numerical and theoretical analysis, the dynamic properties of the isolator including the influence of the fluid damping and inertia mass on the equivalent stiffness, the relation between the isolator's equivalent damping and the fluid damping, the fluid capacity of the linking tube, and the equivalent mass of the liquid column were analyzed in depth. Conclusions about stiffness and damping obtained from the test results correspond well with those from the theoretical analysis, but the identification results of the equivalent mass, which show that the negative correlation of equivalent mass of the liquid column with its response amplitude seems controversial. An assumption is proposed to explain the abnormal characteristics of the liquid column. However, the exact model of the inertia track needs further exploration and verification.

Expression, purification, and characterization of a novel amylosucrase from Neisseria subflava

Amylosucrase (ASase) is a glucosyltransferase, which catalyzes the de novo synthesis of amylose-like polymers from sucrose. In the present study, ASase from Neisseria subflava (NsAS) was cloned, sequenced, and expressed in Escherichia coli. The production of NsAS was achieved by inducting gene expression with 0.2 mM isopropyl-β-d-thiogalactopyranoside. The molecular mass of the Ni-NTA column purified NsAS analyzed by SDS-PAGE was determined to be 72 kDa. NsAS exhibited maximal activity at 45 °C and pH 8.0, and showed strong thermal stability at 40 °C with a half-life of 385 h. The reaction pattern of NsAS at [sucrose] range of 0.1–1.0 M showed that at 0.7 M of [sucrose], the production yield of insoluble linear α-(1,4)-glucans reached 24% maximum, and any further increase in [sucrose] resulted in a slight decrease in yield. Meanwhile, the production yield of turanose significantly increased from 16 to 29% by increasing [sucrose] from 0.1 to 1.0 M. The synthesized glucan had degrees of polymerization (DP); for 0.1, 0.4, 0.7, and 1.0 M sucrose, the DP values were 77, 49, 39, and 31 respectively. These results suggested that NsAS would be a promising candidate for food industrial production of linear α-(1,4)-glucans and turanose as a next generation sweetener.

Toward quantitative forecasts of volcanic ash dispersal: Using satellite retrievals for optimal estimation of source terms

AbstractAirborne volcanic ash is a hazard to aviation. There is an increasing demand for quantitative forecasts of ash properties such as ash mass load to allow airline operators to better manage the risks of flying through airspace likely to be contaminated by ash. In this paper we show how satellite‐derived mass load information at times prior to the issuance of the latest forecast can be used to estimate various model parameters that are not easily obtained by other means such as the distribution of mass of the ash column at the volcano. This in turn leads to better forecasts of ash mass load. We demonstrate the efficacy of this approach using several case studies.

Implementation of Neural Predictive Control To Distillation Column

This paper presents a neural predictive controller that is applied to distillation column. Distillation columns represent complex multivariable system, with fast and slow dynamics, significant interactions and directionality. A phenomenological model (i.e. a model derived from fundamental equation like mass and energy balance) of a distillation column is very complicated. For this reason, classical linear controller, such as PID (Proportional, Integral and Derivative) controller, will provide robustness only over relatively small range operation because of complexity and operation without lack of robustness. In this work, a neural network is developed for modeling and controlling a distillation column based on measured input-outputdata pairs. In distillation column, a neural network is trained on the unknown parameters of the system. The resulting implementationof the neural predictive controller is able to eliminate the most significant obstacles encountered in conventional predictive control application by facilitating the development of complex multivariable models and providing a rapid, reliable solution to the control algorithm. Controller design and implementation are illustrated for a plant frequently referred to in the literature. Result are given for simulation experiments, which demonstrate the advantage of the neural based predictive controller both at the transient region and at the steady state region to overcome any overshoots.Keywords : neural predictive controller, distillation column, complex multivariable models