scholarly journals Mass transfer volumetric coefficient and droplet diameter in liquid-liquid dispersions stirred with a paddle impeller with wire gauze.

1993 ◽  
Vol 26 (2) ◽  
pp. 227-229 ◽  
Author(s):  
Setsuro Hiraoka ◽  
Noboru Kamei ◽  
Yoshihito Kato ◽  
Yutaka Tada ◽  
Katsuya Asai ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Droplet Diameter ◽  
Wire Gauze

scholarly journals Dinamika tetes dalam kolom isian

2018 ◽  
Vol 7 (1) ◽  
pp. 710
Author(s):  
Danu Ariono ◽  
Dwiwahju Sasongko ◽  
Priyono Kusumo
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Size Distribution ◽  
Droplet Size ◽  
Droplet Diameter ◽  
Mass Transfer Rate ◽  
Packed Column ◽  
Droplet Size Distribution ◽  
Droplet Dynamics

To date, evaluation of the performance of liquid-liquid extraction in packed columns has not been able to produce satisfactory results, because the correlations used in this evaluation are empirical in nature, with a very limited range of validity. One of the causes of this limitation is the use of the assumption that the dynamics of liquid dispersed in droplets is constant (in terms of shape, dimensions, and numbers), so that the mass transfer interfacial area and mass transfer coefficient in the column are assumed to be constant. In reality, dynamics of droplets in a column is not constant, due to the imbalance between droplet coalescence and disintegration. For a given droplet diameter, there is an increase in numbers of droplets due to coalescence of smaller droplets, and a  decrease in numbers of droplets due to disintegration into smaller droplets. These coalescence and disintegration phenomena may be caused by various factors, including the existence of packings which impede the flow of droplets. These phenomena impact the mass transfer rate from continuous to dispersed phase, and vice versa, due to a variation in the interfacial contact area and mass transfer coefficient. The observation of droplet dynamics from droplet formation until its motion through void spaces between packings is a critical factor in developing a model that can describe the performance of the packed column. The dynamics of droplets is influenced by various operational and physical variables.  A droplet dynamics experiment has been undertaken, aimed at obtaining the droplet size distribution at specific heights along the column. This distribution is to be used to develop mass transfer coefficient correlations in the continuous and dispersed phases.Keywords: droplet size distribution, packed column Abstrak Evaluasi unjuk kerja ekstraksi cair-cair dalam kolom isian (packed column) hingga saat ini belum dapat memberikan hasil yang memuaskan karena korelasi-korelasi yang  digunakan  masih  bersifat  empiris serta daerah keberlakuannya sangat terbatas. Salah satu penyebab keterbatasan berlakunya korelasi tersebut ialah penggunaan anggapan bahwa dinamika cairan yang terdispersi dalam bentuk tetesan bersifat konstan (bentuk, ukuran serta jumlahnya), sehingga harga luas perpindahan massa dan harga koefisien perpindahan massa dalam kolom dianggap tetap. Kenyataannya dinamika tetesan dalam kolom tidak konstan akibat adanya tetesan yang bergabung dan pecah dalam jumlah yang  tidak sama. Pada suatu harga diameter tetesan tertentu, ada penambahan jumlah tetesan akibat penggabungan tetesan­ tetesan yang ukurannya lebih kecil serta adanya pengurangan jumlah tetesan akibat pecahnya tetesan menjadi tetesan-tetesan yang lebih kecil. Peristiwa penggabungan dan pemecahan tetesan dapat disebabkan berbagai faktor temasuk adanya isian yang menghalangi gerakan tetesan. Kejadian tersebut akan mempengaruhi laju proses perpindahan massa dari fasa kontinyu ke fasa  terdispersi  atau sebaliknya, karena adanya variasi luas permukaan kontak serta koefisien perpindahan massanya. Pengamatan dinamika tetesan mulai saat pembentukan tetes hingga pergerakannya saat melewati sela-sela isian merupakan faktor penting dalam  membangun model  yang  dapat menggambarkan unjuk kerja kolom isian. Dinamika tetesan tersebut dipengaruhi oleh berbagai variabel operasi dan variabel fisik. Eksperimen dinamika fetes yang dilakukan diarahkan untuk memperoleh distribusi ukuran tetes pada posisi ketinggian tertentu dan distribusi tersebut akan digunakan untuk pengembangan  korelasi koefisien perpindahan massa difasa  dispersi danfasa kontinyu.Kata kunci: distribusi ukuran tetes, kolom isian.

Mass transfer for woven and knitted wire gauze substrates: Experiments and modelling

2009 ◽  
Vol 147 ◽  
pp. S120-S124 ◽  
Author(s):  
Andrzej Kołodziej ◽  
Joanna Łojewska
Keyword(s):  
Mass Transfer ◽  
Wire Gauze

scholarly journals Heat and Mass Transfer of Droplet Vacuum Freezing Process Based on Dynamic Mesh

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Lili Zhao ◽  
Yuekai Zhang ◽  
Zhijun Zhang ◽  
Xun Li ◽  
Wenhui Zhang
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Droplet Diameter ◽  
Dynamic Mesh ◽  
Freezing Process ◽  
Freezing Time ◽  
Droplet Temperature ◽  
Obvious Effect ◽  
Initial Droplet ◽  
Vacuum Freezing

A numerical simulation using dynamic mesh method by COMSOL has been developed to model heat and mass transfer during vacuum freezing by evaporation of a single droplet. The initial droplet diameter, initial droplet temperature, and vacuum chamber pressure effect are studied. The surface and center temperature curve was predicted to show the effect. The mass transfer rate and radius displacement were also calculated. The results show the dynamic mesh shows well the freezing process with the radius reduction of droplet. The initial droplet diameter, initial droplet temperature, and vacuum pressure have obvious effect on freezing process. The total freezing time is about 200 s, 300 s, and 400 s for droplet diameter 7.5 mm, 10.5 mm, and 12.5 mm, respectively. The vacuum pressure less than 200 Pa is enough for the less time to freezing the droplet, that is, the key point in freezing time. The initial droplet temperature has obvious effect on freezing but little effect on freezing temperature.

Assessment of the limiting step of mass transfer in n-hexadecane biodegradation in a bubble column reactor

2010 ◽  
Vol 62 (4) ◽  
pp. 906-914 ◽  
Author(s):  
Guillermo Quijano ◽  
Sergio Huerta-Ochoa ◽  
Mariano Gutiérrez-Rojas
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Mass Transfer ◽  
Surface Tension ◽  
Aqueous Phase ◽  
Oxygen Transfer ◽  
Bubble Column ◽  
Droplet Diameter ◽  
Bubble Column Reactor ◽  
Limiting Step

A mathematical model was developed to assess limiting step of mass transfer in the n-hexadecane (HXD) biodegradation by a microbial consortium. A double Monod kinetic (oxygen and HXD) for biomass production was successfully used to describe the experimental data. Good fitting (r2 = 0.92) between the model solution and experimental data was obtained. The overall mass transfer coefficients for HXD, kLaHXD, and oxygen, kLaO2, were experimentally determined and biosurfactant production was indirectly determined through surface tension measurements in the aqueous phase. It was observed that a surface tension reduction from 65 (0 h of culture) to 47 mN m−1 (240 h of culture) was related to a decrease of 52% in the HXD droplet diameter and to an increase of 63% in kLaHXD, respect the initial values. Conversely, kLaO2 was repressed up to 37% compared to the initial value. The maximum rate analysis based on the mathematical model showed that HXD transfer was up to 5-fold lower than its consumption. On the contrary, oxygen transfer was always higher than its consumption. Thus, the limiting step under the working conditions was the HXD transfer to the aqueous phase. However, slight reductions in kLaO2 could result in oxygen transfer limitations during the last 60 h of the cultures.

scholarly journals Modelling Droplet Heat and Mass Transfer in Aero-Engine Bearing Chambers

2019 ◽  
Author(s):  
Dafne Gaviria Arcila ◽  
Hervé Morvan ◽  
Kathy Simmons ◽  
Stephen Ambrose ◽  
Michael Walsh ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Evaporation Rate ◽  
Numerical Study ◽  
Droplet Diameter ◽  
Air Flow ◽  
Core Region ◽  
Evaporation Process ◽  
Data Set ◽  
The Core

Abstract The oil inside aeroengine bearing chambers can be found in many forms, including droplets which interact with the core airflow. The ability to model such bearing chambers computationally is desirable and thus a better understanding of the evaporation process of oil droplets is of great interest. Previous studies have analyzed the flow of isothermal droplets in bearing chambers. However, further investigation is needed into the heating of droplets in the highly rotating core region. This will enable designers to evaluate the behavior of droplets in a chamber and the likelihood that they will evaporate. The aim of this research is to analyze the oil droplet evaporation process under aeroengine bearing chamber representative conditions. An ultimate goal is the ability to predict the oil-air heat and mass transfer in the core flow region, as well as to develop an understanding of the flow inside a droplet, and how this affects evaporation. This latter is important as it has not been studied before. This paper presents the results of a numerical study of the evaporation process of a single droplet under bearing chamber temperature and air flow conditions. The two-phase flow is simulated using ANSYS Fluent with the volume of fluid approach and the evaporation process with the “D−square law”. First, the modelling approach is validated against previous experimental and numerical analysis of fuel droplets in an air flow with heat transfer. The simulation results were in excellent agreement with a benchmarking data set. The validated approach is then applied for investigation to smaller, bearing chamber representative droplets of an oil base stock used in jet engines. The oil evaporation rate was quantified as well as the evolution of droplet diameter, which revealed the effect of different air velocities and temperatures on the droplet. The extent to which evaporation rate increased with air velocity and temperature is quantified. It is concluded that droplets of initial diameters less than 200μm that remain in the chamber core region for more than 0.3s are likely to evaporate completely. This study allows us to estimate droplet heat and mass transfer and the associated phase change in a bearing chamber. It also provides best practice to predict the performance of small droplets under the effects of high temperature and velocity convective air flows. In future work this methodology will be applied in simulations in a representative bearing chamber to predict how the cooling process is affected by oil evaporation.

scholarly journals Modeling of the Drying Kinetics of Slurry Droplet in Spray Drying

2012 ◽  
Vol 11 (2) ◽  
pp. 1 ◽  
Author(s):  
Boris Golman
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Spray Drying ◽  
Parametric Study ◽  
Suspended Solids ◽  
Droplet Diameter ◽  
Gas Temperature ◽  
Drying Time ◽  
Droplet Drying ◽  
Kinetics Of

The detail analysis of the heat and mass transfer between the droplet containing suspended solids and the drying gas was carried out numerically. The temperature and moisture distributions within the slurry droplet were calculated during the first and second drying phases. The parametric study revealed that the droplet drying time decreases with increasing the drying gas temperature and decreasing the droplet diameter.

Experimental and numerical study of mass transfer efficiency in new wire gauze with high capacity structured packing

2018 ◽  
Vol 54 (16) ◽  
pp. 2706-2717 ◽  
Author(s):  
Younes Amini ◽  
Javad Karimi-Sabet ◽  
Mohsen Nasr Esfahany ◽  
Masoud Haghshenasfard ◽  
Abolfazl Dastbaz
Keyword(s):  
Mass Transfer ◽  
Numerical Study ◽  
High Capacity ◽  
Transfer Efficiency ◽  
Structured Packing ◽  
Mass Transfer Efficiency ◽  
Wire Gauze

Power Consumption and Gas-Liquid Mass Transfer Volumetric Coefficient in a Mechanically Agitated Vessel with Wire-Gauze Impeller.

2001 ◽  
Vol 34 (5) ◽  
pp. 600-605 ◽  
Author(s):  
SETSURO HIRAOKA ◽  
YOSHIHITO KATO ◽  
YUTAKA TADA ◽  
SHINICHIRO KAI ◽  
NAOAKI INOUE ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Power Consumption ◽  
Agitated Vessel ◽  
Liquid Mass ◽  
Wire Gauze ◽  
Liquid Mass Transfer
Sign in / Sign up

Export Citation Format

Share Document