scholarly journals Liquid distribution and its effect on local mass transfer in a packed column of Pall rings

2021 ◽  
Author(s):  
Yongjia Zhu
Keyword(s):  
Mass Transfer ◽  
Gas Flow ◽  
Transfer Coefficients ◽  
Liquid Distribution ◽  
Fully Developed Flow ◽  
Flow Rates ◽  
Local Mass ◽  
Local Mass Transfer ◽  
Liquid Distributor ◽  
Wall Flow

The spatial variations of liquid distribution and local mass transfer coefficient in a 0.30-m column of 25.4-m Pall rings were investigated. The data of liquid distribution was collected with a 39-cell liquid collector and a wall-flow tube from a doubled-wall section in the column at the packing-support level. The local mass transfer coefficients were measured via the electrochemical technique by individual cathodic nickel-coated Pall rings placed at various spatial positions. Both measurements were conducted at various fluid flow rates with three liquid distributor designs at different bed heights. Liquid distribution and local mass transfer coefficients observed were far from uniform in the column. The wall flow developed along the packed bed until a fully developed flow pattern was reached. With more uniform initial liquid distribution, the less packing height needed to reach the fully developed flow pattern along with higher the mass transfer efficiency in the column. Ladder-type liquid distributor (LLD) showed less angular effect in measurements. Increasing the liquid flow rate slightly improved the uniformity of liquid distribution and enhanced the mass transfer. No influence of gas flow rate on liquid distribution and mass transfer coefficient was found at the range of gas flow rates used. These gas flow rates were much lower than the loading point. Liquid maldistribution factor and mass transfer maldistribution factor decreased with increases in the uniformity of the initial liquid distribution. These values were 0.21(0.48). 0.16(0.26) and 0.14(0.22) for single-point liquid distributor (SPLD), cross-type liquid distributor (CLD) and LLD, respectively. By comparison, a good agreement was observed on the relation of liquid maldistribution factor and mass transfer maldistribution factor.

scholarly journals Liquid distribution and its effect on local mass transfer in a packed column of Pall rings

2021 ◽  
Author(s):  
Yongjia Zhu
Keyword(s):  
Mass Transfer ◽  
Gas Flow ◽  
Transfer Coefficients ◽  
Liquid Distribution ◽  
Fully Developed Flow ◽  
Flow Rates ◽  
Local Mass ◽  
Local Mass Transfer ◽  
Liquid Distributor ◽  
Wall Flow

The spatial variations of liquid distribution and local mass transfer coefficient in a 0.30-m column of 25.4-m Pall rings were investigated. The data of liquid distribution was collected with a 39-cell liquid collector and a wall-flow tube from a doubled-wall section in the column at the packing-support level. The local mass transfer coefficients were measured via the electrochemical technique by individual cathodic nickel-coated Pall rings placed at various spatial positions. Both measurements were conducted at various fluid flow rates with three liquid distributor designs at different bed heights. Liquid distribution and local mass transfer coefficients observed were far from uniform in the column. The wall flow developed along the packed bed until a fully developed flow pattern was reached. With more uniform initial liquid distribution, the less packing height needed to reach the fully developed flow pattern along with higher the mass transfer efficiency in the column. Ladder-type liquid distributor (LLD) showed less angular effect in measurements. Increasing the liquid flow rate slightly improved the uniformity of liquid distribution and enhanced the mass transfer. No influence of gas flow rate on liquid distribution and mass transfer coefficient was found at the range of gas flow rates used. These gas flow rates were much lower than the loading point. Liquid maldistribution factor and mass transfer maldistribution factor decreased with increases in the uniformity of the initial liquid distribution. These values were 0.21(0.48). 0.16(0.26) and 0.14(0.22) for single-point liquid distributor (SPLD), cross-type liquid distributor (CLD) and LLD, respectively. By comparison, a good agreement was observed on the relation of liquid maldistribution factor and mass transfer maldistribution factor.

Electrochemical Mass Transfer Measurements of CO2 in MDEA Solutions

2011 ◽  
Vol 312-315 ◽  
pp. 87-92
Author(s):  
Rocío Maceiras ◽  
Xosé R. Nóvoa ◽  
Angeles Cancela ◽  
Estrella Álvarez
Keyword(s):  
Mass Transfer ◽  
Electrochemical Method ◽  
Gas Flow ◽  
Bubble Column ◽  
Axial Direction ◽  
Co2 Absorption ◽  
Transfer Coefficients ◽  
Conductivity Method ◽  
Flow Rates ◽  
Local Mass Transfer

The mass transfer coefficients at different axial positions in a bubble column have been measured using a conductivity method. Measurements of CO2 absorption in methyldiethanolamine solutions were carried out in a prismatic column 0.06 m side and 1.03 m height. Five electrode pairs were placed at various axial positions in the column. Measurements were conducted at different gas flow rates and amine concentration. It was found that the local mass transfer varied in the axial direction. An experimental model was developed to obtain the absorption rate values using the electrochemical method data. The model agrees quite well with the experimental obtained data.

Measurement of Local Mass Transfer Coefficients in a Cast Model of the Human Upper Respiratory Tract

1986 ◽  
Vol 108 (1) ◽  
pp. 12-18 ◽  
Author(s):  
L. M. Hanna ◽  
P. W. Scherer
Keyword(s):  
Mass Transfer ◽  
Respiratory Tract ◽  
Nasal Cavity ◽  
Upper Respiratory Tract ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Local Mass ◽  
Local Mass Transfer ◽  
Cast Model ◽  
Upper Respiratory

Local mass transfer coefficients measured using the naphthalene sublimation technique in an acrylic cast model of the human upper respiratory tract are reported as the Sherwood numbers for the corresponding regions. A steady air flow rate of 12 L per min was used for all measurements. Values of the Sherwood number are seen to be highest in the nasal cavity and proximal nasopharynx while a minimum value occurs just downstream from the larynx. Local values of the Nusselt number obtained in the trachea and proximal nasal cavity assuming a complete heat and mass transfer analogy agree well with in-vivo physiological measurements. The mass transfer coefficients found can be incorporated into an analytical model of respiratory heat and water vapor transfer or into a model of pollutant gas uptake in the respiratory tract.

scholarly journals The flow and mass transfer characteristics of concentric gas-liquid flow in an advanced static mixer

2020 ◽  
pp. 24-24
Author(s):  
Huibo Meng ◽  
Zhonggen Li ◽  
Yanfang Yu ◽  
Mengqi Han ◽  
Shuning Song ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Liquid Flow ◽  
Operating Conditions ◽  
Static Mixer ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Local Mass ◽  
Transfer Characteristics ◽  
Local Mass Transfer ◽  
Gas Liquid Flow

The fluid dynamic and mass transfer characteristics of concentric upward gas-liquid flow were studied in the industrial static mixer with four equally spaced helical inserts (FKSM). The numerical simulations of gas volume fraction in Kenics mixer had a good agreement with the numerical and experimental results provided by Rabha et al. The characteristics of radial gas void fraction and local mass transfer coefficients in the FKSM were evaluated under different operating conditions. The velocity profiles of concentric air phase accelerated by the bubble forces firstly became sharp and narrow until z/l=-3.27 and then slowly decreased and stabilized at z/l=-1.5 before entering the first mixing element. Some extra unimodal profile of radial gas holdup gradually generated near the rectangle cross sections of mixing elements. The ?G gradually enlarged from r/R=0.2 to r/R=0.55 and then weakened from r/R=0.65 to r/R=0.874. The air void fractions in the bulk flow region decreased with the increasing initial uniform bubble diameter. The inlet effect of first leading edge enhanced the air phase dispersion and local mass transfer coefficients sharply increased from 2.04 to 3.69 times of that in the inlet. The local mass transfer coefficients in each mixing group had unimodal profiles.

Distribution of Local Mass Transfer Coefficients on Walls of Complex-Shape Channels

2001 ◽  
Vol 32 (4-6) ◽  
pp. 7
Author(s):  
N. I. Pecherkin ◽  
V. Yu. Chekhovich ◽  
Bulat I. Nigmatulin
Keyword(s):  
Mass Transfer ◽  
Complex Shape ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Local Mass ◽  
Local Mass Transfer
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