scholarly journals Numerical study on the polymer drawing of the spunbonding process

2015 ◽  
Vol 19 (4) ◽  
pp. 1473-1474
Author(s):  
Li-Li Wu ◽  
Kang Yang ◽  
Ting Chen
Keyword(s):  
Flow Field ◽  
Numerical Computation ◽  
Numerical Study ◽  
Air Flow ◽  
Filament Diameter

A polymer drawing model is established for the spunbonding process through numerical computation of the air flow field. The results show that the model predicts the filament diameter effectively. The paper contributes to in-depth understanding of the spunbonding technology.

Forced Flow Heat and Mass Transfer to a Cylinder Surrounded by a Porous Material With Applications to NBC Protective Clothing

2002 ◽  
Author(s):  
Michael P. Sobera ◽  
Chris R. Kleijn ◽  
Paul Brasser ◽  
Harry E. A. Van den Akker
Keyword(s):  
Mass Transfer ◽  
Flow Field ◽  
Heat And Mass Transfer ◽  
Protective Clothing ◽  
Numerical Study ◽  
Air Flow ◽  
Forced Flow ◽  
Dimensionless Numbers ◽  
Flow Heat ◽  
Human Limb

Increased permeability of clothing material can reduce the heat load caused by Nuclear-Biological-Chemical (NBC) protective clothing, but implies reduced protection. The goal of the present work is to study the influence of the air permeability on human comfort and safety. A numerical study is presented of the air flow with heat and mass transfer around a cylinder, mimicking a human limb, placed in a turbulent external air flow and surrounded by protective clothing. The problem is described in terms of the relevant dimensionless numbers. The dependence of the flow field underneath the clothing and the heat and mass transfer to the limb are studied as a function of the Reynolds, Darcy and Damko¨hler numbers, which are a measure for the wind speed, clothing permeability and adsorptivity of the poisonous gas, respectively. The air flow simulations are validated with experiments, in which the flow field around a bare cylinder and in the space between a cylinder and its porous cover, is measured with LDA. Scaling rules for heat and mass transfer are presented.

scholarly journals Study on the air flow field of the drawing conduit in the spunbonding process

2015 ◽  
Vol 19 (4) ◽  
pp. 1443-1444
Author(s):  
Li-Li Wu ◽  
Hong-Mei Sun ◽  
Ting Chen
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Optimal Design ◽  
Flow Field ◽  
Good Accuracy ◽  
Air Flow ◽  
Numerical Prediction ◽  
Filament Diameter

The air flow field of the drawing conduit in the spunbonding process has a great effect on the polymer drawing, the filament diameter and orientation. A numerical simulation of the process is carried out, and the results are compared with the experimental data, showing good accuracy of the numerical prediction. This research lays an important foundation for the optimal design of the drawing conduit in the spunbonding process.

scholarly journals Effects of the conduit geometry on the air flow field in the spunbonding process

2015 ◽  
Vol 19 (4) ◽  
pp. 1457-1458
Author(s):  
Li-Li Wu ◽  
Hong-Mei Sun ◽  
Ting Chen
Keyword(s):  
Flow Field ◽  
Field Model ◽  
Air Flow ◽  
Air Velocity ◽  
Filament Diameter ◽  
Narrow Section

In the spunbonding process, the air flow field of the drawing conduit affects the polymer drawing and therefore the filament diameter greatly. Effects of the conduit parameters on the air flow field are studied using the previously established air flow field model. The results show that longer narrow section, longer contracting section and larger height of narrow entry are of benefit to increasing the air velocity, thus helpful for decreasing the filament diameter.

scholarly journals Flow Field Effect on the Performance of Direct Formic Acid Membraneless Fuel Cells: A Numerical Study

Processes ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 746
Author(s):  
Jin-Cherng Shyu ◽  
Sheng-Huei Hung
Keyword(s):  
Fuel Cells ◽  
Flow Field ◽  
Formic Acid ◽  
Power Density ◽  
Liquid Flow ◽  
Numerical Study ◽  
Air Flow ◽  
Airflow Rate ◽  
Air Breathing ◽  
Membraneless Fuel Cells

The performance of both air-breathing and air-feeding direct formic acid membraneless fuel cells (DFAMFCs) possessing different flow fields were numerically investigated in this study at given concentration and flow rate for both fuel and electrolyte. Single serpentine, stepwise broadening serpentine, multi-serpentine and parallel channel were tested as liquid flow field, while single serpentine, stepwise broadening serpentine, multi-serpentine and pin channel were tested as air flow field. The channel width was either 0.8 mm or 1.3 mm. The simulation results showed that the air-breathing DFAMFC having identical flow field for both fuel and electrolyte yielded highest cell output. The air-breathing DFAMFC having SBS liquid flow field yielded a maximum power density of 10.5 mW/cm2, while the air-breathing DFAMFC having S(1.3) liquid flow field produced an open circuit voltage of 1.0 V owing to few formic acid penetration into the cathode. Concerning the air-feeding DFAMFCs, the DFAMFC having SBS liquid flow field and MS(0.8) air flow field yielded highest peak power density, 12 mW/cm2, at an airflow rate of 500 sccm. Considering the power generated by the DFAMFCs together with the power consumed by the air pump, DFAMFC having SBS liquid flow field and Pin(0.8) air flow field could be the preferred design.

Numerical Study of the Combined Free-Forced Convection and Mass Transfer Flow Past a Vertical Porous Plate in a Porous Medium with Heat Generation and Thermal Diffusion

2006 ◽  
Vol 11 (4) ◽  
pp. 331-343 ◽  
Author(s):  
M. S. Alam ◽  
M. M. Rahman ◽  
M. A. Samad
Keyword(s):  
Mass Transfer ◽  
Flow Field ◽  
Differential Equations ◽  
Forced Convection ◽  
Heat Generation ◽  
Numerical Study ◽  
Porous Plate ◽  
Integration Scheme ◽  
Suction Parameter ◽  
Transfer Flow

The problem of combined free-forced convection and mass transfer flow over a vertical porous flat plate, in presence of heat generation and thermaldiffusion, is studied numerically. The non-linear partial differential equations and their boundary conditions, describing the problem under consideration, are transformed into a system of ordinary differential equations by using usual similarity transformations. This system is solved numerically by applying Nachtsheim-Swigert shooting iteration technique together with Runge-Kutta sixth order integration scheme. The effects of suction parameter, heat generation parameter and Soret number are examined on the flow field of a hydrogen-air mixture as a non-chemical reacting fluid pair. The analysis of the obtained results showed that the flow field is significantly influenced by these parameters.

NUMERICAL STUDY OF HEAT TRANSFER AND AIR FLOW IN HEATED GREENHOUSES

2008 ◽  
Author(s):  
Nadia Dihmani ◽  
Ahmed Mezrhab ◽  
Larbi Elfarh ◽  
Hicham Bouali ◽  
Hassan Naji
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Air Flow

scholarly journals Model of thermal buoyancy in cavity-ventilated roof constructions

2021 ◽  
pp. 174425912098418
Author(s):  
Toivo Säwén ◽  
Martina Stockhaus ◽  
Carl-Eric Hagentoft ◽  
Nora Schjøth Bunkholt ◽  
Paula Wahlgren
Keyword(s):  
Analytical Model ◽  
Flow Rate ◽  
Numerical Study ◽  
Air Flow ◽  
Wind Pressure ◽  
Air Flow Rate ◽  
Test Set ◽  
Air Cavity ◽  
Thermal Buoyancy ◽  
The Impact

Timber roof constructions are commonly ventilated through an air cavity beneath the roof sheathing in order to remove heat and moisture from the construction. The driving forces for this ventilation are wind pressure and thermal buoyancy. The wind driven ventilation has been studied extensively, while models for predicting buoyant flow are less developed. In the present study, a novel analytical model is presented to predict the air flow caused by thermal buoyancy in a ventilated roof construction. The model provides means to calculate the cavity Rayleigh number for the roof construction, which is then correlated with the air flow rate. The model predictions are compared to the results of an experimental and a numerical study examining the effect of different cavity designs and inclinations on the air flow rate in a ventilated roof subjected to varying heat loads. Over 80 different test set-ups, the analytical model was found to replicate both experimental and numerical results within an acceptable margin. The effect of an increased total roof height, air cavity height and solar heat load for a given construction is an increased air flow rate through the air cavity. On average, the analytical model predicts a 3% higher air flow rate than found in the numerical study, and a 20% lower air flow rate than found in the experimental study, for comparable test set-ups. The model provided can be used to predict the air flow rate in cavities of varying design, and to quantify the impact of suggested roof design changes. The result can be used as a basis for estimating the moisture safety of a roof construction.

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