Area Of Packing Research Articles

Length and Area of an Apollonian Packing

Summary We prove two theorems about the circular Apollonian packing. The first states that the circles used in the packing have an infinite total length. The second states that the largest circle is covered by the other circles used in the packing, up to an area of Lebesgue measure zero. Our proofs are elementary and only use basic coordinate geometry.

Evaluating CO2 desorption performance of MEA solution with MnOx/HZ catalytic packings by visualization method

The high energy consumption in the CO2 desorption process is one of the main issues of the chemical absorption method. To address this issue, a MnOx modified HZSM-5 catalyst (MnOx/HZ) was prepared by impregnation method and used as catalytic packing to improve the CO2 desorption rate in the monoethanolamine (MEA) solution. Since the catalytic effects mainly work around the catalytic packing, a visualization method, which can measure the CO2 desorption rate per unit surface area (vCO2/area) of a single packing, is proposed to avoid some uncertain effects occurring as the conventional bubbling method is used. The results showed that the vCO2/area of the MnOx/HZ catalytic packing is 10.06 μmol·cm−2·s−1 at 80 °C, which is 1.78 times of that of HZSM-5 and 15 to 60 times of that of commercial packings. Actually, the MnOx/HZ has more Brønsted and Lewis acid sites than HZSM-5 according to the pyridine adsorption infrared spectroscopy (Py-IR) characterization. As a result, the apparent activation energy (Ea) of the CO2 desorption reaction with the addition of MnOx/HZ can be reduced by 58.6% and 18% compared with the addition of ceramic saddle ring packing and HZSM-5, respectively. However, the catalytic performance of MnOx/HZ packings degrades gradually due to the blockage of micropores by the reaction product, that needs to be settled in the future.

ANALYSIS OF THE EFFECT OF DOWN TIME ON PRODUCTIVITY AT PT. EASTERN PEARL FLOUR MILLS MAKASSAR

Productivity is a comparison between the results achieved (output) with the overall required resources (input) or a comparison between the results achieved with the role of labor per unit time.
 The purpose of this study was to study Down Time analysis techniques for productivity in a wheat processing company (PT. Eastern Pearl Flour Mills Makassar), which produces wheat flour products of the Gatotkaca, Gunung, Kompas and Gerbang types. Down Time is the amount of time when a tool/machine cannot operate due to failure, but the factory can still operate because there are still other tools/machines that can replace functions so that the production process can still run.
 Based on the data analysis of the calculation of down time for manpower, it shows that the existence of down time during the process will affect the level of productivity (actual and standard). The value of down time from the calculation of working hours minus work effectiveness results in down time for each production area each month. The manpower down time results from all areas, namely in the area of 0 minutes/month. While the amount of data from the analysis of down time calculations for machines in all areas has a higher number of machine down times, namely in the milling area of 28 hours. And for the lowest results, namely in the area of unloading, cleaning, and packing, it is 0 hours.

Measurements of the effective mass transfer areas for the gas–liquid rotating packed bed

Rotating packed bed (RPB) is one of the most effective gas–liquid mass transfer enhancement reactors, its effective specific mass transfer area (ae) is critical to understand the mass transfer process. By using the NaOH–CO2 chemical absorption method, the ae values of three RPB reactors with different rotor sizes were measured under different operation conditions. The results showed that the high gravity factor and liquid flow rate were major affecting factors, while the gas flow rate exhibited minor influence. The radius of packing is the dominant equipment factor to affect ae value. The results indicated that the contact area depends on the dispersion of the liquid phase, thus the centrifugal force of rotating packed bed greatly influenced the ae value. Moreover, the measured ae/ap (effective specific mass transfer area/specific surface area of packing) values were fitted with dimensionless correlation formulas. The unified correlation formula with dimensionless bed size parameter can well predict the experimental data and the prediction errors were within 15%.

Study of particle packing and paste rheology in alkali activated mixtures to meet the rheology demands of 3D Concrete Printing

The rheological behavior of concrete mixtures made with alkali-activated fly ash-slag (AAFS) binder paste is investigated for varying aggregate content. The static yield stress, plastic viscosity and thixotropy of the mixtures are evaluated and related with the performance in 3D Concrete Printing (3DCP). The thixotropy of the concrete mixture is primarily influenced by AAFS binder paste composition and does not change with the aggregate content. Rheology control of the AAFS binder paste is achieved using additives like nano-clay, which enhance the buildup of internal structure and provide thixotropy in the concrete mixtures. The paste content, the surface area of aggregate, and the packing of solids in a concrete mixture influence its yield stress. The static yield stress increases sensitively in relation to the proportion of the surface area of the solids to the paste volume content in the concrete mixture. The minimum requirement of the paste content from packing of solids in the mixture is given by the Fuller-Thompson curve. Excess paste content in proportion to the demand determined from the surface area of aggregate and packing of solids in the concrete mixture produces a decrease in the static yield stress. For producing AAFS concrete mixtures suitable for 3DCP, the paste content in the concrete mixture should meet the requirement of paste demand, which depends on the aggregate content and packing of solids.

Characteristics and Risk Factors of Recurrent Epistaxis in Geriatric Patients

Background and Objectives Recurrent epistaxis requiring emergency department (ED) visits results in increased morbidity in the elderly and associated with high health care costs. This study is to analyze the frequency and characteristics of epistaxis patients in the elderly and to find out the risk factors and effective treatment for recurrent epistaxis. Subjects and Method We studied retrospectively the clinical cases of 977 emergency patients and 155 patients, aged over 65, for the treatment of epistaxis during the last 10 years from January 2008 to January 2018. The group A, comprised of 95 patients (68.29%), was treated with an initial treatment. The group B, which comprised of 60 patients (38.71%), visited for re-bleeding following an initial treatment. Results Patients made 2 to 10 ED visits due to re-bleeding and 32 of the 60 patients (53.5%) visited twice. The electrocauterization was the most common (61.7%) for treatment method during rebleeding, followed by posterior packing (18.3%). The factors that increases the risk of recurrent epistaxis are anticoagulants, posterior epistaxis, anterior packing, inefficient ED packing. There was no correlation between comorbidities and rebleeding. Conclusion Accurate medical history taking of anticoagulants may enable personnel to provide more effective management of these patients. The most important factors in the failure of primary care were not being able to find the precise area of bleeding and ineffective packing during the initial treatment. Therefore, it is important that we must carefully check the areas using the endoscope to decrease the failure of initial treatment of epistaxis.

Determining the Effective Mass Transfer Area in Three-Phase Fluidized Bed with Low Density Inert Solids

The absorption process is strongly influenced by the effective mass transfer area. In this study the effective mass transfer area in gas-solid-liquid three-phase fluidized bed was determined, in a fluidizing column having an internal diameter of 0.14 m and a height of 1.10 m. The solid packing is made of plastic hollow spheres of 0.01 m diameter, with 415 m2/m3 geometric area and a density of 170 Kg/m3. The absorption of carbon dioxide from the air-carbon dioxide mixture with molar concentration of 0.05M, 0.08M and 0.1M CO2 into sodium hydroxide aqueous solutions of 0.5N and 1.0 N has been employed as test reaction. The experiments were conducted with liquid load changing from 6.49 to 16.24 m�/(m� h) and gas velocity of 1.1 m/s and 2.1 m/s. It was found that the effective mass transfer area increased both with the increase of the gas velocity and the increase of the liquid spray density. It has been observed that the effective mass transfer area in gas-solid-liquid three-phase fluidized bed absorber is from three to eight times higher than the geometric area of the solid packing. A mathematical correlation has been established in order to predict the effective mass transfer area,under the specified conditions, with a deviation of less than 5%.

Shelflife Estimation of Seaweed Dodol in OPP Packaging by Using Accelerated Shelf Life Test Method

AbstracThis research is carried out due to the limited information on the shelf-life of food product in Indonesia, especially in South Sulawesi. In addition, there is no sufficient information on the self-life of packed seaweed dodol which produced by using scientific method. Seaweed dodol has a high economic value. The objective of this research was to estimate the self-life of seaweed dodol which is produced in traditional scale (micro, small, and middle scale bussiness) using the scientific method. Accelerated Shelf Life Testing (ASLT) Method is one of methods used in determining the shelf life of seaweed dodol based on critical water content and graining as indicators of quality deterioration. The isotermic sorption model of products was obtained from isotermic sorption curve formed from the relationship between the values of water activity (aw) and the equilibrium moisture content (Me). Moreover, five different models of isotermic sorption were tested. They were Hasley, Chen-Clayton, Henderson, Caurie, and Oswin model. The results showed that the Henderson model was the appropriate model in describing the isotermic sorption phenomena at seaweed dodol with the Mean Relative Deviatian (MRD) of 1.4. By integrating the critical moisture content (Mc), packing permeability (OPP), sample weights (Ws), the surface area of packing (A) and the saturated vapor pressure (Po) into the equation Labuza, the self-life of seaweed dodol at temperature of 30 °C and RH of 78% was 56 days.

Determining the Effective Mass Transfer Area in Three-Phase Fluidized Bed with Low Density Inert Solids

The absorption process is strongly influenced by the effective mass transfer area. In this study the effective mass transfer area in gas-solid-liquid three-phase fluidized bed was determined, in a fluidizing column having an internal diameter of 0.14 m and a height of 1.10 m. The solid packing is made of plastic hollow spheres of 0.01 m diameter, with 415 m2/m3 geometric area and a density of 170 Kg/m3. The absorption of carbon dioxide from the air-carbon dioxide mixture with molar concentration of 0.05M, 0.08M and 0.1M CO2 into sodium hydroxide aqueous solutions of 0.5N and 1.0 N has been employed as test reaction. The experiments were conducted with liquid load changing from 6.49 to 16.24 m³/(m² h) and gas velocity of 1.1 m/s and 2.1 m/s. It was found that the effective mass transfer area increased both with the increase of the gas velocity and the increase of the liquid spray density. It has been observed that the effective mass transfer area in gas-solid-liquid three-phase fluidized bed absorber is from three to eight times higher than the geometric area of the solid packing. A mathematical correlation has been established in order to predict the effective mass transfer area,under the specified conditions, with a deviation of less than 5%. Keywords: Effective mass transfer area, three-phase fluidized bed with low density inert solid packing, mass transfer model, chemical method, reaction regime

Mass Transfer Rate Parameters of Sulzer EX Laboratory Scale Gauze Structured Packing

Sulzer EX packing is widely used in lab-scale separation studies owing to its high efficiency, low theoretical stage height and small pressure drop. In this work the three fundamental characteristic mass transfer parameters of this packing, effective gas-liquid contact area (ae) gas-film and liquid-film mass transfer coefficient (kG) and (kL) are measured in a 0.19 mm ID counter-flow absorption column using aqueous liquids. With end effects removed, the results show that the effective gas liquid contact area is independent of gas and liquid loads and reaches about 90 % of the geometric area of the packing. Correlations of the dimensionless gas and liquid phase mass transfer parameters are determined as ??hG = 0.048 ????G1.0 ????G0.33 and ??h L = 0.050 ????L0.4????L0.5.

Mass Transfer Parameters for Packings: Effect of Viscosity

The effect of liquid viscosity (μL) on the effective mass transfer area (ae) and liquid film mass transfer coefficient (kL) of packing must be known to determine packing height. Most existing correlations are based on water and are not applicable to viscous systems. In this work, ae, kL, and gas film mass transfer coefficient (kG) were measured in a 0.43 m ID packed column with 0.5–3 m of packing. Liquid viscosity was varied from 0.8 to 70 mPa·s by adding glycerol to water. Liquid viscosity has an insignificant effect on ae over the range of μL investigated. The total dependence of kL on μL is −0.75, of which −0.35 is indirect influence through diffusivity, and −0.4 is direct influence through liquid turbulence. Universal mass transfer models for packing were developed as functions of packing geometry, operating condition, and fluid property.

Novel Absorber Configurations Using Aqueous Piperazine for CO2 Capture from NGCC Flue Gas

Novel absorber intercooling configurations were evaluated for CO2 capture with 8 m piperazine (PZ) for NGCC flue gas (3.5mol % CO2) over a range of operating conditions (90–99% CO2 capture, LLDG = 0.15–0.27mol CO2/mol alkalinity, L/G = 0.7–1.4mol/mol). The improved intercooling configurations included solvent recycle and hybrid intercooling where the gas stream is split and contacted in multiple passes by the solvent. In both advanced designs, absorber performance is enhanced by introducing a new degree of freedom: an independent liquid-to-gas ratio (L/G) in high-intensity contacting sections. The higher L/G sections benefit from enhanced mass transfer due to turbulence generated in the packing (modeled via mass transfer coefficients and interfacial area of packing) and improved intercooling function (large solvent rate to moderate temperatures). In addition, the direct contact cooler upstream of the absorber was integrated into the column with the amine solvent performing the flue gas cooling function in a packed section with a higher L/G. Hybrid contacting outperformed all other configurations at all conditions evaluated, providing up to 70% reduction in packing area over the baseline absorber. A simplified 1x3+1 hybrid design (2 column sections) provided packing reduction over the baseline design and reduced complexity over other advanced configurations. At 99% CO2 removal, only a 2x3+1 hybrid contacting scheme was able to integrate the direct contact cooler and achieve 99% removal at the conditions evaluated in this work. The hybrid design benefits from enhanced intercooling (multiple discrete intercooling points to approximate continuous solvent cooling and large L/G) and a better approximation of countercurrent contacting than the solvent recycle design.

DESIGN OF A PACKED-BED ABSORPTION COLUMN CONSIDERING FOUR PACKING TYPES AND APPLYING MATLAB

In the present work, a packed bed absorption column is designed to recover certain amounts of ethanol contained in a gaseous stream. Four packing types (50-mm metal Hiflow® rings, 50-mm ceramic Pall® rings, 50-mm metal Top Pak® rings and 25-mm metal VSP® rings) are considered in order to select the most appropriate one in terms of column dimensions, pressure drop and mass-transfer results. Several design parameters were determined including column diameter (D), packing height (Z), overall mass-transfer coefficient (Km) and gas pressure drop (P/Z), as well as the overall number of gas-phase transfer units (NtOG), overall height of a gas-phase transfer unit (HtOG) and the effective surface area of packing (ah). The most adequate packing to use for this absorption system constitutes the 25-mm metal VSP® rings, since it provided the greatest values of Km (0.325 kmol/m3.s), and ah (169.57 m-1), as well as the lowest values of both Z (0.6 m) and HtOG (0.145 m), meaning that it will supply the higher mass-transfer conditions with the lowest column dimensions. The influence of both gas mixture (QG) and solvent (mL) feed flowrates on D, Z, Km, P/Z, NtOG and HtOG was also evaluated for the four packing considered. The design methodology was solved using computing software MATLAB® version 7.8.0.347 (R2009a) (Math Works, 2009), and also Microsoft Excel®.D

Investigation of effective interfacial area in a rotating packed bed with structured stainless steel wire mesh packing

Packing plays an important role on the mass transfer and mixing in a rotating packed bed (RPB) which is regarded as an important gas-liquid reactor or contactor for process intensification. Stainless steel wire mesh packing exhibits good mass transfer performance when applied in a RPB. However, its construction repeatability and mechanical strength should be improved. Therefore, we introduced and designed a novel structured stainless steel wire mesh packing, aiming to overcome the above problems. In this work, the effective interfacial area (ae) in the packing and cavity zones of a RPB with four different types of structured stainless steel wire mesh packings was investigated at various rotational speeds, gas flow rates, and liquid flow rates by using a NaOH-CO2 mass transfer system. A brief analysis of the gas-liquid mass transfer interface area (A) and utilization ratio of packing’s specific surface area (wp) is presented. A modified correlation for the effective interfacial area in the packing zone of the RPB with structured stainless steel wire mesh packing was also proposed, and the predicted values were found to be in agreement with the experimental values with deviations generally within ±15%.

Fabrication of Improved Dye-Sensitized Solar Cells with Anatase/Rutile TiO₂Nanofibers.

Using the method of electrospinning followed by annealing at different temperatures, TiO₂ nanofibers with different phases were successfully prepared. Dye sensitized solar cells were fabricated using these TiO₂ nanofiber mats as the photoanode. The morphologies and photovoltaic performance of the cells were investigated in detail. By optimizing the annealing temperature and the thickness of the photoanode, a power conversion efficiency of 6.12% and a fill factor of 0.65 were obtained. A treatment with TiCl₄was employed to further improve the photoanodes. The resulting DSSC device employing the TiC4-treated anodes exhibited an improved efficiency of 7.06% and a fill factor of 0.73. These performance improvements were attributed to the different crystalline structures of the mesoporous composite anatase/rutile TiO₂ nanofibers, which featured stair-step energy levels and the high surface area of close grain packing. These positive results suggest that the electrospun nanofiber photoanode provides an effective means of efficient charge transport for application in dye-sensitized solar cells.

Modeling study on CO2 and H2S simultaneous removal using MDEA solution

This study presents a rate-based model of an absorber packed column for simultaneous absorptions of acid gases into methyldiethanolamine (MDEA) aqueous solution. The model is in good agreement with experimental data. The parametric study showed that the concentration of acid gases in the sweet gas stream increases by decrease in the specific surface area of packing. The peak of selectivity factor decreases with the increase in the mole ratio of CO2/H2S in the gas feed along the packed column. The sensitivity analysis reveals that selecting the accurate correlations of the gas-side mass transfer coefficient and specific surface area is vital.

Cleaner technology systems for surface finishing: evaporative coolers for close circuiting low temperature plating process

Abstract In the electroplating process, the rinse system generates large quantities of wastewater requiring treatment prior to disposal to municipal systems. The use of conventional water treatment systems is a challenge due to the presence of hazardous components. In addition, this does not solve the problem of the generation of rinse wastewater, but only treats it. Thus the focus was on point-source reduction technologies, specifically the application of a three-stage low flow counter current rinse for recovery of the rinse water in the plating bath, enabling close circuiting of the plating bath rinse system. However, recovery of the rinse water into the plating bath is impeded by the low rates of evaporation, especially in the low temperature plating baths. Alternative methodologies to heating were investigated to facilitate evaporation, with evaporative cooling being identified as the most feasible option. Evaporative cooling facilitates evaporation, whilst maintaining the plating bath temperature within the operational limits. For the recovery of the rinse water in the plating bath, the rate of evaporation in the plating bath must be equivalent to the fresh make-up water requirements of the rinse tanks. The Closed Circuit Plating System (CCPS) model was developed to enable the proper design and/or implementation of an evaporative cooler; whereby the user specified inputs are evaluated in achieving the required evaporation rates for the recovery of the rinse water in the plating bath. The key characteristic of the CCPS model is the minimum requirement of proprietary plating solution specific information. The inputs for the model are chemical composition of the plating solution, flowrates, temperature and height of the cooling tower. The outputs from the model are evaporation rates and equilibrium temperatures of the plating bath and cooling tower. The primary limitation of the CCPS model is that it is based on an air–water system. Single and multiple variable sensitivity analyses were performed on the plating plant operational parameters to determine their influence on close circuiting of the rinse plating system: plating solution composition and operational temperature; ambient air temperature; air flow rate and the surface area of the packing in the cooling tower. The results from the model indicated the upper limit plating solution operational temperature, high air flow rates, low ambient air temperature and large surface area of packing facilitated water evaporation rates and lower equilibrium temperatures in the plating bath and cooling tower. The sensitivity analyses will allow the electroplater to optimise the operating conditions to achieve the required evaporation rates for recovery of the rinse water into the plating bath, while simultaneously maintaining the outputs of the electroplating plant and reducing the rinse wastewater generation to almost zero.

Effect of interfacial phenomena on mass transfer performance of an absorber packed closely with cylindrical packing

The mass transfer performance is usually affected by the wetting of the packing surface with absorbent solution, and the wetted surface can be affected by interfacial disturbances resulting from the gradient in surface tension between water vapor and absorbent solution. In order to discuss the effects of interfacial phenomena on mass transfer performance of water vapor absorbed by triethylene glycol (TEG) and lithium bromide (LiBr) solutions, an absorber packed closely with cylindrical packing was designed in this study and the packing material was polyvinyl chloride. In addition, the interfacial behaviors were observed from water droplet positioned on the surface of absorbent solution, and the surface stress was defined and calculated to analyze how mass transfer performance was affected by the stress. Experimental results show that surface stress increases with increases in concentration of TEG solution. The surface stress increases significantly when the concentration of TEG solution exceeds 92wt.% The area of packing wetted by TEG solution increases as the concentration of TEG solution and humidity increase. Therefore, the mass transfer performance also increases with the higher concentration and higher humidity.

Performance evaluation of a solar and wind aided cross-flow evaporator for RO reject management

In the present study, an attempt was made to evaluate the performance of a solar and wind aided cross-flow evaporator prototype as an alternative to conventional evaporators for concentrating reverse osmosis (RO) rejects. The performance of the solar and wind aided cross-flow evaporator was evaluated for different operating conditions such as (i) wind velocity, (ii) relative humidity in the ambient air, (iii) temperature of inlet water, (iv) trickling rate and (v) different packing geometries. Empirical correlations for evaporation loss were developed, as a function of the above variables. Among the various synthetic and natural media tried, plastic flexi ring was the most effective. Solar and wind aided cross-flow evaporator with random packing performed better than that with structured packing, as long as the air flow is not blocked by the packing. Studies revealed that the exposed surface area and depth of packing in the direction of wind are the important dimensions of the natural evaporator. It was also found that solar pre heating significantly increased the evaporation rate. Evaporation rate decreased as the concentration of salt in the water increased.

MINLP optimization of mechanical draft counter flow wet-cooling towers

In this paper, the problem of the optimal design of mechanical draft counter flow cooling towers that meets a set of specified constraints is formulated as a mixed-integer nonlinear programming (MINLP) problem. The Merkel's method is used to specify the characteristic dimensions of cooling towers, together with empirical correlations for the loss and overall mass transfer coefficients in the packing region of the tower. Water-to-air mass ratio, water mass flow rate, water inlet and outlet temperatures, operational temperature approach, type of packing, type of draft, height and area of the tower packing, total pressure drop of air flow, power consumption of the fan, and water consumption provide the set of optimization variables. The MINLP problem is formulated so as to minimize the total annual cost of the cooling tower. The performance of the proposed procedure is shown with the solution of six examples.