Study of a laminar falling film flowing over a wavy wall column: Part I. Numerical investigation of the flow pattern and the coupled heat and mass transfer

Flow pattern and heat and mass transfer characteristics for a film flowing over a vertical wavy column are numerically investigated in a laminar flow regime. In our approach, the heat and mass transfer coefficients are avoided in order to include hydrodynamics directly in the heat and mass transfer rates. As a consequence the numerical model is decomposed into two steps. Firstly, the flow pattern for a film with a free interface is developed. Secondly, heat and mass transfer are investigated with the incorporation of velocity fields. The heat and mass transfer coefficients increase in laminar flow

Multi-scale model for heat and mass transfer during rice drying

Grain drying is a simultaneous heat and moisture transfer problem. The modeling of such a problem is of significance in understanding and controlling the drying process. The main goal of this study was to predict the heat and mass transfer processes during deep-bed rice drying. To achieve this, first, CFD simulations were carried out to analyze the external flow and temperature fields at steady-state for a control volume of a stationary rice bed. The model was used to predict the convective heat and mass transfer coefficients in the rice bed, and correlations were developed for the convective heat and mass transfer coefficients as a function of drying air flow rate. Then, the coupled CFD and diffusion model developed by ElGamal, Ronsse, Radwan & Pieters (2013) to investigate the heat and mass transfer for thin-layer drying of rice was extended to volumetric heat and mass transfer in a deep-bed of rice using the predicted heat and mass transfer coefficients. All models were solved numerically using the finite element method. The model was used to predict the air temperature, as well as the grain moisture content and temperature at different locations of the dryer during the drying process. The theoretical predictions of moisture and temperature profiles inside a deep-bed of rice were verified by experimental data from literature. The average mean relative deviation values for the prediction of grain moisture content varied between 1.00 to 3.13%

Effect of Distributed Superficial-Velocity in Deep-Bed Grain Drying

This paper deals with influence of velocity field distribution to heat and mass transfer process in deep bed grain dryers. Two-dimensional (2D) models of deep-bed grain dryers were built by considering simultaneously momentum, heat, and mass transfer in the drying air phase. The Navier-Stokes momentum equations are applied to simulate pressure drop and velocity field of the drying airflow. Effect of velocity distribution to the heat and mass transfer coefficient distribution were simulated along the height of grains bed. The dynamic equations are solved numerically by using finite difference method by utilization of alternating direction implicit method, while the momentum equations are solved numerically by utilization of SIMPLE algorithm. The simulation results showed that velocity distribution along the grains bed - 5 cm of bed height - did not so influenced to the heat and mass transfer coefficient. Further, the vector plot of drying air superficial velocity field and contour of pressure distribution along deep bed of grain was simulated

Heat and Mass Transfer in Cold Regions Soils

The work upon which this report is based was made possible by a cooperative aid agreement between the U.S. Forest Service, Institute of Northern Forestry, Fairbanks, Alaska, and the Institute of Water Resources, University of Alaska. Contributions to this study were also made by the University of California at Davis and Ohio State University. The collection of winter data on pore pressures was made possible by a separate grant by the Office of Water Research and Technology (project A-053 ALAS)

Atmospheric composition affects heat- and mass-transfer processes

For environmental control system functions sensitive to atmospheric composition, components are test-operated in helium-oxygen and nitrogen-oxygen mixtures, pure oxygen, and air. Transient heat- and mass-transfer tests are conducted for carbon dioxide adsorption on molecular sieve and for water vapor adsorption on silica gel

Study of heat and mass transfer applications in the field of engineering by using OpenFOAM

The aim of the project is to study OpenFOAM software and establish a well-based guide of standard and complex heat and mass transfer applications in engineering. OpenFOAM is a free, open source CFD software package. By being open, OpenFOAM offers users complete freedom to customise and extend its existing functionality. On the other hand, OpenFOAM offers a quick start user guide and there also is little available documentation and several examples. Thus, the project intends to: - Prepare an introductory and complete user guide to OpenFOAM with solved standard heat and mass transfer applications to the beginners, specially bachelor students ‐ Numerical simulation of complex heat and mass transfer applications in engineering with OpenFOAM in two‐ and three‐dimensional problems ‐ Practice in developing engineering projects by combining technical work with economic and environmental aspectsThe main tasks to be carried out in this project will be to: - Edit problems solved with OpenFOAM including explanations and detailed considerations in order to prepare a guide for new learners, specially bachelor students - Work in the study and analysis of heat and mass transfer simulations involving real engineering problems - Determine feasibility of the engineering project to be carried out - Study the socio-economics aspects in fluid dynamics applications solved by numerical simulation and fields of interest - Results analysi

Modeling deep-bed grain drying using Comsol Multiphysics

CFD simulations were carried out to predict the convective heat and mass transfer coefficients in the rice bed, and correlations were developed for the convective heat and mass transfer coefficients as a function of drying air flow rate. The developed correlations were used to extend the coupled CFD and diffusion model developed by ElGamal et al. (2013) for thinlayer rice drying to volumetric heat and mass transfer in a deep-bed of rice. All mathematical models were solved using the Comsol Multiphysics® simulation program v4.3 (Comsol Inc, Palo Alto), which uses the finite element method to solve the model equations. The model was used to predict the air temperature, as well as the grain moisture content and temperature at different locations of the dryer during the drying process. The theoretical predictions of moisture and temperature profiles inside a deep-bed of rice were verified by experimental data from literature

An overview of recent applications of computational modelling in neonatology

This article has been made available through the Brunel Open Access Publishing Fund.This paper reviews some of our recent applications of Computational Fluid Dynamics (CFD) to model heat and mass transfer problems in neonatology and investigates the major heat and mass transfer mechanisms taking place in medical devices such as incubators, radiant warmers and oxygen hoods. It is shown that CFD simulations are very flexible tools that can take into account all modes of heat transfer in assisting neonatal care and improving the design of medical devices.Brunel Open Access Publishing Fun

Heat and mass transfer in air-fed pressurised suits

Air-fed pressurised suits are used to protect workers against contamination and hazardous environments. The specic application here is the necessity for regular clean-up maintenance within the torus chamber of fusion reactors. The current design of suiting has been developed empirically. It is, therefore, very desirable to formulate a thermofluids model, which will be able to define optimum designs and operating parameters. Two factors indicate that the modelling should be as comprehensive as possible. Firstly, the overall thermofluids problem is three-dimensional and includes mass as well as heat transfer. The fluid field is complex, bounded on one side by the human body and on the other by what may be distensible, porous and multi-layer clothing. In this paper, we report firstly the modelling necessary for the additional mass and heat transport processes. This involves the use of Fick's and Fourier's laws and conjugate heat transfer. The results of an initial validation study are presented. Temperatures at the outlet of the suits were obtained experimentally and compared with those predicted by the overall CFD model. Realistic three-dimensional geometries were used for the suit and human body. Calculations were for turbulent flow with single- and two-component (species) models