CFD Simulation of Human Coughs and Sneezes: A Study in Droplet Dispersion, Heat, and Mass Transfer

2010 ◽  
Author(s):  
Amir A. Aliabadi ◽  
Steven N. Rogak ◽  
Sheldon I. Green ◽  
Karen H. Bartlett
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Cfd Simulation ◽  
Near Field ◽  
Dynamics Simulation ◽  
Evaporation Process ◽  
Buoyancy Effect ◽  
Computational Fluid Dynamics Simulation ◽  
Droplet Dispersion ◽  
Ambient Relative Humidity

A Computational Fluid Dynamics simulation of near-field cough and sneeze droplet dispersion and heat and mass transfer is developed. In this study various sources of variability in cough and sneeze processes are considered. These are variations in injection volume (0.5l, 2.5l, and 5.0l) and ambient relative humidity (20%, 40% and 60%). There are a total of 9 simulations for coughs and sneezes in a quiescent background. A large ensemble (5000) of droplets are tracked with diameters in the range 1–500micron. Evaporation and dispersion are predicted as a function of droplet size. Generally, fine droplets evaporate faster than large droplets. Higher relative humidities slow the evaporation process. Larger droplets have greater axial penetration. They also exhibit greater vertical drop due to the effect of gravity. Sideway penetration is increased by higher injection volumes. The buoyancy effect due to thermal energy of the injection is very weak, at least for the 10-second computation duration.

scholarly journals ANALYSIS OF HEAT AND MASS TRANSFER ON COOLING TOWER FILL

2020 ◽  
Vol 14 (1) ◽  
pp. 25
Author(s):  
Abdul Aziz Rohman Hakim ◽  
Engkos Achmad Kosasih
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Relative Humidity ◽  
Heat And Mass Transfer ◽  
Cooling Tower ◽  
Stream Velocity ◽  
Design Data ◽  
Analogy Method ◽  
Ambient Relative Humidity ◽  
Air Stream

This paper discusses heat and mass transfer in cooling tower fill. In this research, dry bulb temperature at the bottom fill, ambient relative humidity, air stream velocity entering fill, dry bulb temperature leaving the fill, relative humidity of air leaving the fill, inlet and outlet water temperature of cooling tower were measured. Those data used in heat and mass transfer calculation in cooling tower fill. Then, do the heat and mass transfer calculation based on proposed approch. The results are compared with design data. The design and analogy method showed different  result. The parameter which influence the heat transfer at cooling tower are represented by coefficient of heat transfer hl and coefficient of mass transfer k­l. The differencies result between design and analogy method shows that there is important parameter which different. Deeply study needed for it.

Experimental and Numerical Research on Steam Direct Contact Condensation Process in Automatic Depressurization System of AP1000

2020 ◽  
Author(s):  
Yuhao Zhang ◽  
Li Feng ◽  
Zhimin Qiu ◽  
Jingpin Fu ◽  
Daogang Lu
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Direct Contact ◽  
Cfd Simulation ◽  
Condensation Process ◽  
Validation Data ◽  
Numerical Work ◽  
Pressurized Water ◽  
Temperature And Pressure ◽  
Contact Condensation

Abstract In the third generation pressurized water reactor AP1000 plant, the Automatic Depressurization System (ADS) is one of the most important passive safety system. However, the steam Direct Contact Condensation (DCC) microscopic mechanisms are very complicated, which are not very clear yet. Moreover, the high-pressure and high-temperature experiment is very expensive to be conducted for many different test conditions. So in the present work, both the experimental and numerical methods are employed to investigate the steam DCC behavior. The steam DCC experimental bench has been built up, and the key parameters including the flow patterns and steam core temperature distributions are measured to provide validation data for the numerical results. In aspect of the numerical work, CFD simulation on the steam condensation is conducted. The heat and mass transfer process is simulated through the three-dimension commercial software FLUENT 16.0. Some of the key heat and mass transfer correlations are added by User Defined Function (UDF). The key parameters including the condensation steam fraction, temperature, and pressure, etc. are analyzed, which reflect the major heat transfer characteristics. According to the results, the expansion-compression-steam tail could be observed in both the numerical and experimental results. In essential, the steam fraction, temperature, and pressure distributions are determined by the equilibrium and transformation between the thermal dynamic energy and kinetic energy. The results provide working references for the practical ADS steam spraying condensation process in AP1000 reactor.

CFD Simulation of Hydrodynamics, Heat and Mass Transfer Simultaneously in Structured Packing

2008 ◽  
Vol 6 (1) ◽  
Author(s):  
M.R. Khosravi Nikou ◽  
M.R. Ehsani ◽  
M. Davazdah Emami
Keyword(s):  
Experimental Data ◽  
Mass Transfer ◽  
Pressure Drop ◽  
Heat And Mass Transfer ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Theoretical Plate ◽  
Absolute Relative Error ◽  
Gas Liquid Flow ◽  
Counter Current

This paper describes the results of computational fluid dynamic modeling of hydrodynamics, heat and mass transfer simultaneously in Flexipac 1Y operated under a counter-current gas-liquid flow condition. The simulation was performed for a binary mixture of methanol-isopropanol distillation. The pressure drop, the height of equivalent to theoretical plate (HETP) and temperature distribution across the column were calculated and compared with experimental data. The mean absolute relative error (MARE) between CFD predictions and experimental data for the pressure drop, HETP and temperature profile are 20.7%, 12.9% and 2.8%, respectively.

scholarly journals A Study of Steady Buoyancy-Driven Dissipative Micropolar Free Convection Heat and Mass Transfer in a Darcian Porous Regime with Chemical Reaction

2007 ◽  
Vol 12 (2) ◽  
pp. 157-180 ◽  
Author(s):  
O. Anwar Bég ◽  
R. Bhargava ◽  
S. Rawat ◽  
H. S. Takhar ◽  
Tasweer A. Bég
Keyword(s):  
Mass Transfer ◽  
Velocity Field ◽  
Heat And Mass Transfer ◽  
Chemical Reaction ◽  
Reaction Rate ◽  
Near Field ◽  
Packed Bed ◽  
Darcy Number ◽  
Reaction Model ◽  
Chemical Reaction Rate

In the present paper we examine the steady double-diffusive free convective heat and mass transfer of a chemically-reacting micropolar fluid flowing through a Darcian porous regime adjacent to a vertical stretching plane. Viscous dissipation effects are included in the energy equation. Assuming incompressible, micro-isotropic fluid behaviour the transport equations are formulated in a two-dimensional coordinate system (x, y) using boundary-layer theory. The influence of the bulk porous medium retardation is modeled as a drag force term in the translational momentum equation. Transformations render the conservation equations into dimensionless form in terms of a single independent variable, η, transverse to the stretching surface. A simplified first order homogenous reaction model is also used to simulate chemical reaction in the flow. Using the finite element method solutions are generated for the angular velocity field, translational velocity field, temperature and species transfer fields. The effects of buoyancy, porous drag and chemical reaction rate are studied. Chemical reaction is shown to decelerate the flow and also micro-rotation values, in particular near the wall. Mass transfer is also decreased with increasing chemical reaction rate. Increasing Darcy number is shown to accelerate the flow. Applications of the study include cooling of electronic circuits, packed-bed chemical reactors and also the near field flows in radioactive waste geo-repositories.

Comprehensive dynamic modelling and CFD simulation of heat and mass transfer in wetted wall absorption reactors

2014 ◽  
Vol 92 (10) ◽  
pp. 1749-1765 ◽  
Author(s):  
Seyyed Mohammad Hossein Hashemi Amrei ◽  
Saber Memardoost ◽  
Sima Asadi ◽  
Asghar Molaei Dehkordi
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Cfd Simulation ◽  
Dynamic Modelling

Modeling heat and mass transfer in osmotic evaporation process

AIChE Journal ◽  
2003 ◽  
Vol 49 (2) ◽  
pp. 300-308 ◽  
Author(s):  
J. Romero ◽  
G. M. Rios ◽  
J. Sanchez ◽  
S. Bocquet ◽  
A. Savedra
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Evaporation Process
Sign in / Sign up

Export Citation Format

Share Document