Function Of Operating Parameters Research Articles

Thermal and chemical reaction performance analyses of steam methane reforming in porous media solar thermochemical reactor

In order to investigate the thermochemical reaction performance of steam methane reforming (SMR), the steady heat and mass transfer model coupled with thermochemical reaction kinetics is developed for the volumetric porous media solar thermochemical reactor. The local non-thermal equilibrium (LNTE) model with modified P1 approximation is adopted to investigate the temperature distributions of the solid phase and fluid phase. For the solid phase energy equation, the irradiative heat transfer coupled with chemical reaction kinetics is programmed via User Defined Functions (UDFs). The concentrated solar irradiation is not only considered as the boundary condition at the reactor front surface, but also as the irradiative heat source in the whole volume of reactor. The parametric studies are conducted to investigate the thermal and hydrogen production performances as a function of operational parameters. The numerical results indicate that SMR reaction has big effects on temperature distribution. The generated H2 mole fraction decreases sharply with the increasing of fluid inlet velocity, porosity and mean cell size. The generated H2 mole fraction increases significantly with the increasing of incident solar irradiance.

Kinetic modeling of BB41 photocatalytic treatment in a semibatch flow photoreactor using a nano composite film

In this study, photocatalytic degradation of Basic Blue 41 (BB41) was investigated using TiO2 nano composite films stuffed with definite dosage of TiO2 nanopowder, immobilized on glass substrates using the sol–gel dip-coating method, in a semibatch rectangular photoreactor (irradiated with a UV light). The coatings were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 adsorption–desorption isotherm analysis and coating thickness gauge. The kinetic of the degradation of the BB41 was described with the Langmuir–Hinshelwood kinetic model. Experimental results indicate that the degradation rate of BB41 follows pseudo-first-order kinetics. A model was developed with nonlinear regression, for prediction of pseudo first-order rate constants (kapp) as a function of operational parameters, including initial concentration of BB41 (10–50 mg/L), flow rate (6–15 L/h) and temperature (20–40 °C). The following equation was obtained by kinetic modeling Kapp=436.65172.19271+2.1927[BB41]00.1937FRexp6859RT. Calculated data from the model are in good agreement with the experimental results. Electrical energies per order (EEO) estimated from the calculated and experimental data show that EEO depends on the operational parameters, considerably. Photocatalytic mineralization of BB41 was monitored by chemical oxygen demand (COD) decrease, changes in UV–Vis spectra and FT-IR spectra.

Environmental Bioremediation of Dyes by <i>Pseudomonas </i><i>a</i><i>eruginosa </i>ETL-1 Isolated from Final Effluent Treatment Plant of Ankleshwar

Economical and bio-friendly approaches are needed to remediate dye-contaminated wastewater from various industries. In this study, a novel bacterial strain capable of decolorizing triarylmethane dyes was isolated from a textile wastewater treatment plant in Ankleshwar, Gujarat, India. The bacterial isolate was identified as <i>Pseudomonas aeruginosa</i> ETL-1<i> </i>and was shown to decolorize three triarylmethane dyes tested within 24 h with color removal in the range of 72% to 96%. Decolorization efficiency of the bacterium was a function of operational parameters (aeration, dye concentration, temperature, and pH) and the optimal operational conditions obtained for decolorization of the dyes were: pH 7-8, 35°C and culture agitation. Effective color removal within 24 h was obtained at a maximum dye concentration of 50 mg/l. Dye decolorization was monitored using a scanning uv/visible spectrophotometer which indicated that decolorization was due to the degradation of dyes into non-colored intermediates. Phytotoxicity studies carried out using <i>Triticum aestivum</i>, and <i>Lens esculenta </i>revealed the triarylmethane dyes exerted toxic effects on plant growth parameters monitored. However, significant reduction in toxicity was obtained with the decolorized dye metabolites thus, indicating the detoxification of the dyes following degradation by <i>Pseudomonas aeruginosa </i>ETL-1.

UMTS 상태 천이 방식에서 에너지 소비와 활성 지연간의 트레이드오프 성능 분석

이동통신 시스템은 무선 자원과 배터리 전력을 효율적으로 관리하기 위해 사용자 상태 천이 방식을 정의하고 있다. 이러한 상태 천이 방식에서는 에너지 소비가 많은 상태가 기본적으로 짧은 접속 지연을 제공하므로 에너지와 지연 성능 사이에 트레이드오프 관계가 존재한다. 본 논문에서는 이동 응용 서비스의 트래픽 속성을 고려하여 UMTS 시스템의 사용자 상태 천이 방식을 분석한다. 상태 천이 방식의 마르코프 모델링을 통하여 에너지 소비량과 활성 지연을 수학적으로 도출하고 운용 파라미터에 따라 이들의 트레이드오프 관계를 파악한다. 분석 결과로 도출된 에너지-지연 트레이드오프 곡선은 주어진 상태 천이 방식이 달성 가능한 성능 한계를 보여주며 지연 요구사항을 보장하면서 에너지 소비를 최소화하는 최적 운용 전략을 제시한다. Mobile communication systems define user state transition mechanisms in order to manage radio resources and battery power efficiently. In the state transition mechanism, a state with a higher energy consumption inherently offers a shorter access delay, so there is a tradeoff between the energy and delay performances. In this paper, we analyze the user state transition mechanism of UMTS by considering the bursty traffic attributes of mobile applications. We perform a numerical evaluation for both the energy consumption and the activation delay by Markov modeling of the state transition mechanism, and investigate their tradeoff relationship as functions of operational parameters. The resulting energy-delay tradeoff curves clearly show an achievable performance bound of the user state transition mechanism and also offer an optimal operation strategy to minimize the energy consumption while guaranteeing the delay requirement.

Kinetic Modeling of Photocatalytic Degradation of an Azo Dye Using Nano-TiO2/Polyester

Photocatalytic degradation of Reactive Orange 16 (RO16) was investigated using immobilized TiO2 nanoparticles on polyester support in exposure of UV irradiation in recirculated tubular photoreactors. Utilization of the polyester as a support has several advantages, such as low price, remarkable surface area, flexibility, and durability. Moreover, the prepared TiO2/polyester was successfully applied for the photocatalytic degradation of RO16 in aqueous media for several times without any discernible diminution in its activity. Applied TiO2 nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Experimental results indicate that the degradation rate of RO16 follows pseudo-first-order kinetics. With nonlinear regression, a model was developed for prediction of pseudo-first-order rate constants (kapp) as a function of operational parameters, including temperature (295–328K), flow rate (5–15 L·min−1), and initial concentration of RO16 (5–25 mg·L−1) as $$k_{\rm app} = 2.20 ( \exp { [- 7427 / \rm RT} ]) ( FR ) ^{0.5034} [ {0.112 / (1 + 0.112 [ \rm RO16 ] _0} )] .$$ Calculated data from the model are in good agreement with the experimental results. Electrical energies per order (EEO) were estimated from the calculated and experimental data show that EEO depends on the operational parameters, considerably. To monitor the mineralization of RO16, chemical oxygen demand (COD) measurements were carried out during the UV/TiO2 process. COD measurement results indicated that all organic substances were completely mineralized after 5 h of UV irradiation.

Experimental characterization of a linear electric molten zone in silicon

An electric current is used to create and maintain a linear molten zone in silicon. The electrical signature of the electric molten zone (EMZ) is described in detail. The measurement of the EMZ width as a function of operational parameters has shown good agreement with published data on the electrical conductivity of liquid silicon, and suggests a simple method for the estimation of the width of the EMZ from the electrical data.

Experimental evaluation of two pilot-scale membrane distillation modules used for solar desalination

► Two pre-commercial MD modules tested under real conditions coupled to solar field. ► Operation variables and salt concentration effects on performance were evaluated. ► Compact versus multi-stage layouts comparatively assessed. ► Notable performance enhancements achieved through multi-stage concept. ► MD coupled with solar energy proved suitable but still highly energy consuming. This paper presents the analysis of the performance of two different pre-commercial MD desalination modules developed by the Singaporean enterprise Keppel Seghers tested under real conditions intermittently for at least 2400 h during two years, directly coupled with a static collector's solar field. Both modules are based on the air gap membrane distillation (AGMD) configuration with a total membrane surface of 9 m 2 each. One of the modules is a compact single design while the other one consists of three stages connected in series. The performance of both modules (i.e. distillate production and quality, thermal efficiency and recovery ratio) has been characterized as a function of operational parameters. Especial attention was paid to thermal efficiency issues. Aqueous NaCl solutions of 1 and 35 g L −1 concentration were used as feed. Minimum specific thermal energy consumption was in the range of 1805 kWh t m −3 for the compact prototype and around 294 kWh t m −3 for the multi-stage one. Distillate quality was excellent (in the range of 2–5 μS cm −1 ) and practically not affected by feed flow rate, hot inlet temperature or feed salt concentration. The paper shows the production and distillate's quality as well as the thermal efficiency results as a function of the operational parameters.

Experimental method for the assessment of agricultural spray retention based on high-speed imaging of drop impact on a synthetic superhydrophobic surface

Spray retention is a critical stage in pesticide application since non-retained drops can result in reduced efficacy, economic loss and environmental contamination. Current methods of retention assessment are based either on field experiments or laboratory studies. The former are usually performed on whole plants under realistic spray application conditions but offer no insight into the physics behind the process whilst the latter mainly focus on drop impact physics but are usually restricted to unrealistically low drop speeds. The aim of the paper is to devise an experimental method to investigate retention at drop scale level as a function of operational parameters but under controlled realistic conditions. A device based on high-speed video was developed to study retention on a synthetic superhydrophobic surface for a moving agricultural nozzle. The sizes and velocities of the drops generated were measured immediately before impact using image analysis. Impact class proportions were established and transition boundaries between impact outcomes were quantified using Weber number. Two contrasting experiments were performed to investigate the ability of method to detect small parametric changes. The insignificant changes in spray pattern that occur from pressure changes, did not significantly affect impact class boundaries, but changed the proportion of drops in each class because of size and velocity variations. The use of a surfactant reduced the volume median diameter of the spray, increased impact speed and changed the impact class boundaries. The method should allow a precise parametric investigation of spray retention in laboratory and close to field conditions.

Influence of operational parameters and kinetics analysis on the photocatalytic reduction of Cr(VI) by immobilized ZnO

In the present work the performance of immobilized ZnO on a glass plate with the heat attachment method has been described for photoreduction of Cr(VI) to the less harmful Cr(III) at different operational parameters. The photoreduction of Cr(VI) on the surface of the immobilized ZnO catalyst was studied as a function of the pH of solution, initial Cr(VI) concentration and ultraviolet (UV) light intensity. Results indicated that the reduction rate decreases with increasing initial concentration of Cr(VI) and initial pH of solution, whereas it increases with increasing UV light intensity. The photoreduction rate of Cr(VI) on the surface of the immobilized ZnO in the presence of O2 as mobile gas is more than Ar and N2. The reduction process of Cr(VI) by immobilized ZnO also could be done under visible light irradiation. Pseudo first-order kinetics were observed for the photoreduction of Cr(VI) at different operational conditions. With non-linear regression analysis a mathematical kinetics model was developed for the pseudo first-order constant (k ap) as a function of operational parameters.

The potential of electrospraying for hydrophobic film coating on foods

There is a continuous need for thinner edible coatings with excellent barrier properties, and this requires new application methods. Electrospraying is known to yield fine droplets of size down to 20μm, giving the potential of very thin and even coatings. A single electrospraying nozzle was used to characterise droplet formation and investigate the formation of thin films on well-defined surfaces. The experimental droplet size was successfully described as a function of operational parameters and liquid properties using scaling relations. The influence of operating parameters as nozzle height and electrostatic potential were evaluated as well.Thin film deposition was experimentally investigated for sunflower oil electro-sprayed on a highly conductive (aluminium) and insulating target surface (Parafilm). For both aluminium foil and Parafilm the droplet deposition was found to be random. For aluminium foil, being a conductive target, this was expected as repellence between droplets on the surface and new droplets is low, due to charge leakage to the ground. For Parafilm, droplet repellence appeared so large that droplets deposited on larger empty spots or were even pushed away from the surface. To evaluate the film formation performance, Monte Carlo simulations were carried out, and it was found that the method is a useful tool to characterise droplet deposition and film formation characteristics.

Measurement of the O2 Dissociation Fraction in RF Low Pressure O2/Ar Plasma Using Optical Emission Spectrometry

Measurement of the oxygen dissociation fraction in RF low pressure oxygen/argon plasma using optical emission spectrometry is presented. The oxygen dissociation fraction and its evolutions as functions of operational parameters were determined using argon as the actinometer. At a pressure of 30 Pa, the oxygen dissociation fraction decreased from 13.4% to 9.5% as the input power increased from 10 W to 70 W. At an input power of 50 W, the oxygen dissociation fraction decreased from 12.3% to 7.7% when the gas pressure increased from 10 Pa to 40 Pa. The influences of operational parameters on the generation of atomic oxygen were also discussed.

Bioremediation and Detoxification of Synthetic Wastewater Containing Triarylmethane Dyes by Aeromonas hydrophila Isolated from Industrial Effluent

Economical and bio-friendly approaches are needed to remediate dye-contaminated wastewater from various industries. In this study, a novel bacterial strain capable of decolorizing triarylmethane dyes was isolated from a textile wastewater treatment plant in Greece. The bacterial isolate was identified as Aeromonas hydrophila and was shown to decolorize three triarylmethane dyes tested within 24 h with color removal in the range of 72% to 96%. Decolorization efficiency of the bacterium was a function of operational parameters (aeration, dye concentration, temperature, and pH) and the optimal operational conditions obtained for decolorization of the dyes were: pH 7-8, 35°C and culture agitation. Effective color removal within 24 h was obtained at a maximum dye concentration of 50 mg/L. Dye decolorization was monitored using a scanning UV/visible spectrophotometer which indicated that decolorization was due to the degradation of dyes into non-colored intermediates. Phytotoxicity studies carried out using Triticum aestivum, Hordeum vulgare, and Lens esculenta revealed the triarylmethane dyes exerted toxic effects on plant growth parameters monitored. However, significant reduction in toxicity was obtained with the decolorized dye metabolites thus, indicating the detoxification of the dyes following degradation by Aeromonas hydrophila.

Evaluation of biological nutrient removal from wastewater by Twin Circulating Fluidized Bed Bioreactor (TCFBBR) using a predictive fluidization model and AQUIFAS APP

A two-phase and three-phase predictive fluidization model based on the characteristics of a system such as media type and size, flow rates, and reactor cross sectional area was proposed to calculate bed expansion, solid, liquid and gas hold up and specific surface area (SSA) of the biofilm particles. The model was subsequently linked to 1d AQUIFAS APP software (Aquaregen) to model biological nutrient removal in two phase (anoxic) and three phase (aerobic) fluidized bed bioreactors. The credibility of the proposed model for biological nutrient removal was investigated using the experimental data from a Twin Circulating Fluidized Bed Bioreactors (TCFBBR) treating synthetic and municipal wastewater. The SSA of bio-particles and volume of the expanded bed were simulated as a function of operational parameters. Two-sided t-tests demonstrated that simulated SCOD, NH(4)-N, NO(3)-N, TN, VSS and biomass yields agreed with the experimental values at the 95% confidence level.

Characterization of an electro-thermal micro gripper and tip sharpening using FIB technique

A micromachined electro-thermal gripper, first introduced by Ivanova et al. (Microelectron Eng 83:1393–1395, 2006), represents a promising candidate for the manipulation and handling of micro or even nano-scaled objects. To further optimize the performance of the device, a detailed electrical and mechanical characterization is needed. Due to the so-called duo-action gripper approach (i.e., a separate actuator for closing and opening action) these investigations focused on the maximum (minimum) opening width being 11.5 μm (3.3 μm), while in rest position a value of 4 μm is feasible. The maximum, electrical input power is limited to 80 mW/actuator element, resulting in a current density of up to 1.27 MA cm−2 in the corresponding metal layers. When applying, however, larger current densities the probability of device failure increases substantially as in combination with an enhanced temperature of about 200°C electromigration effects occur in the metallization. Furthermore, the cut-off frequency and parasitic effects during actuation such as the z-deflection and the increase in length of each arm both showing values of up to 3 μm have been investigated as a function of operation parameters. Finally, the tips of the gripper were sharpened using Focused Ion Beam technique to a radius of less than 1 μm for gripping operations in space-restricted environments or for the manipulation or handling of sub-μm scaled objects.

The simulation of morphology of dissimilar copper–steel electron beam welds using level set method

Abstract In present work, the simulation of morphology and velocity field in dissimilar electron beam welds formed between the metals with limited solubility is described by the example of copper–stainless steel couple. Finite element software COMSOL Multiphysics 3.5 has been employed due to its flexibility in solving of coupled multiphysical problems. The domination of horizontal flows allows reducing the model to two dimensions. Level set method has been used to determine the position of the interface between immiscible components basing on coupled heat transfer and fluid flow pseudo-stationary solution. The evolution of the shape, fluid flow and mixing pattern in function of operational parameters has been demonstrated. The simulated morphology is shown to be in accordance with experimental results: global composition and morphology of the welds.

Computational Modeling of Cell Growth Heterogeneity in a Perfused 3D Scaffold

Our goal was to develop a computational model describing the spatiotemporal evolution of cell heterogeneity within a three-dimensional porous scaffold during cell growth in a perfusion bioreactor. The scaffold was assumed formed by an ensemble of independent parallel cylindrical channels with a defined diameter distribution. The total flow rate partitioning in each channel depends on the effective diameter, which is reduced by the cell growth on the channel wall. The mass balance for one metabolite and the cell volume balance were solved. For each channel diameter, the model simulation provide the spatiotemporal evolution of velocity, shear stress, metabolite concentration, and cell volume growth. In particular, all of these outcomes can be analyzed as a function of channel diameter providing an evaluation of cell property heterogeneity. The model describes that the cell growth can be substantially different in each channel diameter. For instance, in the small diameter channel, cell growth is limited by metabolite mass transport, whereas in the larger diameter channel, shear stress inhibits cell growth. This mathematical model could be an important tool for a priori estimation of the time variation of the cell volume fraction and its degree of heterogeneity as a function of operational parameters and scaffold pore size distribution.

Method of Optimizing Motor and Bit Performance for Maximum ROP

Abstract Downhole motors are widely used to drill vertical, directional and horizontal wells in conjunction with Polycrystalline Diamond Compact (PDC) bits. When a bent housing Positive Displacement Motor (PDM) is oriented for slide drilling to manipulate a well's trajectory, the drill string does not rotate. Consequently, the rate of penetration (ROP) typically decreases. It is therefore important to optimize bottomhole assembly (BHA) performance in conjunction with PDC drill bits. This paper discusses how motor performance data, coupled with an ROP model, can predict the optimal weight-on-bit (WOB) required to derive maximum ROP for a given section of a hole to be drilled. This approach solves the ROP model and determines the ideal WOB with respect to any restrictions that PDM performance equations apply on it. Bit wear is included in the ROP model and an analysis is performed to optimize a given interval of wellbore. The optimization approach is illustrated with two examples for different formation types and one field case comparing the performance of two motors with PDC bits. The optimum WOB, maximum average ROP and differential pressure values are the outputs from the analysis. This analytical approach can be used to determine the optimum PDM/PDC bit combination to achieve maximum ROP through a wide range of operational conditions. Introduction Positive Displacement Motors (PDMs) have gained widespread use in vertical, directional and horizontal drilling applications. In directional and horizontal mode, bent housing PDMs are used to manipulate well trajectory (inclination and azimuth) to intersect bottomhole targets. Slide drilling occurs when the bend in the PDM is oriented in a certain direction. During slide drilling, the drill string does not rotate. In slide drilling mode, bit rotation is generated only from the motor as drilling fluid is pumped through the drill string. Drilling in this mode can significantly reduce ROP and increase well costs. Accordingly, overall performance of bit and motor combinations can have an extremely significant impact on drilling costs. In comparison to using a simple approach like mechanical specific energy (MSE) which is a relative 'local' value as a function of instantaneous operating parameters like WOB and RPM only(1), the approach herein can do a global bit run optimization in the pre-planning and follow-up phases, which include bit selection and detailed design parameters, bit wear throughout the bit run as a function of operating parameters and motor selection and performance. MSE does not consider any of these parameters and is not an overall 'global' ROP or $/m optimization tool. In a PDM, the power section converts hydraulic energy of mud flow into mechanical rotary power ? the reverse action of the Moineau pump principle(2). Each PDM has a helical rotor assembled inside a helical stator. The rotor has one less spiral or lobe than the stator, which results in a continuous seal line between the two. Likewise, the length of helical pitch for the stator is greater than the rotor, which forms cavity spaces between them. These cavities move along the power section from the inlet to outlet by rotating the rotor.

Evaluation of sludge-based carbon as packing material in biofiltration in comparison to classic materials

The main objective of this study is to determine the most rellevant characteristics and physical behaviour of carbon obtained from sludge (SBC) from wastewater treatment facilities and to use it as support material in a biofilter in comparison to classic materials commonly used in this purpose. Materials for comparison were selected according to previous works in the field of biofiltration including organic and inorganic (or synthetic) materials. Results obtained demonstrate that SBC is an acceptable packing material according to the main parameters to be valued in any biofilter: nutrients supply capability, high water retentivity, high adsorption capacity, to provide low pressure drop, allow for biomass attachment or a commitment among them. The study includes the performance of SBC in an operative, lab-scale biofilter besides the characterization of the adsorption capacity and pressure drop as a function of operational parameters.

Advanced Oxidation of Diuron by Photo-Fenton Treatment as a Function of Operating Parameters

Advanced oxidation of diuron in aqueous solution by photo-Fenton treatment was investigated by batch experiments. Effects of operating parameters, namely, the concentrations of pesticide (diuron), hydrogen peroxide (H 2 O 2 ), and ferrous ion [Fe (II)] on oxidation of diuron were investigated by using Box-Behnken statistical experiment design and the response surface methodology. Diuron oxidation by photo-Fenton treatment was evaluated by determining the total organic carbon (TOC), diuron, and adsorbable organic halogen (AOX) removals. Concentration ranges of the reagents resulting in the highest level of diuron oxidation were determined. Diuron removal increased with increasing H 2 O 2 and Fe (II) concentrations, up to a certain level. H 2 O 2 concentration had a more profound effect than diuron and Fe (II) on removal of diuron, TOC, and AOX from the aqueous solution. Complete (100%) disappearance of diuron was achieved after a 15 min reaction period. However, 85% of diuron was mineralized after 240 min, indicating a low level of intermediate formation. Optimal H 2 O 2 /Fe (II)/diuron ratio resulting in maximum diuron (100%), TOC (85%), and AOX (100%) removals was found to be 267/36/25 (mg L -1 ).

Design equation with mathematical kinetic modeling for photooxidative degradation of C.I. Acid Orange 7 in an annular continuous-flow photoreactor

The decolorization of C.I. Acid Orange 7 (AO7), an anionic monoazo dye of acid class was investigated using UV/H(2)O(2) process in an annular continuous-flow photoreactor (ACFP) as a function of oxidant, dye concentrations, reactor length and volumetric flow rate. The removal efficiency of AO7 was a function of operational parameters and increased with increasing initial concentration of H(2)O(2) but it was low at high flow rate and initial concentration of AO7. Results indicated that the decolorization rate was pseudo-first order kinetic with respect to the dye concentration. A rate equation for decolorization of AO7 was obtained by kinetic modeling. Design equation for ACFP reactor was obtained with combination of kinetic model and rearranged tubular reactor design equation. Design equation was used for predicting concentration of AO7 and also electrical energy per order (E(EO)) at different conditions. The calculated results obtained from design equation and kinetic model were in good agreement with experimental data.