Coupling heat and mass transfer for determining individual diffusion coefficient of a hot C3H8–CO2 mixture in heavy oil under reservoir conditions

2016 ◽  
Vol 102 ◽  
pp. 251-263 ◽  
Author(s):  
Sixu Zheng ◽  
Huijuan Sun ◽  
Daoyong Yang
Keyword(s):  
Mass Transfer ◽  
Diffusion Coefficient ◽  
Heat And Mass Transfer ◽  
Heavy Oil ◽  
Reservoir Conditions

Experimental and Theoretical Determination of Diffusion Coefficients of CO2-Heavy Oil Systems by Coupling Heat and Mass Transfer

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Sixu Zheng ◽  
Daoyong Yang
Keyword(s):  
Mass Transfer ◽  
Diffusion Coefficient ◽  
Heat And Mass Transfer ◽  
Heavy Oil ◽  
Diffusion Coefficients ◽  
Binary Interaction ◽  
Co2 Diffusion ◽  
Explicitly Correlated ◽  
Different Temperatures ◽  
Binary Interaction Parameters

By treating heavy oil as multiple pseudocomponents, techniques have been developed to experimentally and theoretically determine diffusion coefficients of CO2-heavy oil systems by coupling heat and mass transfer together with consideration of swelling effect. Experimentally, diffusion tests have been conducted for hot CO2-heavy oil systems with three different temperatures under a constant pressure by using a visualized pressure-volume-temperature (PVT) setup. The swelling of liquid phase in the PVT cell is continuously monitored and recorded during the measurements. Theoretically, a two-dimensional (2D) mathematical model incorporating the volume-translated Peng–Robinson equation of state (PR EOS) with a modified alpha function has been developed to describe heat and mass transfer for hot CO2-heavy oil systems. Heavy oil sample has been characterized as three pseudocomponents for accurately quantifying phase behavior of the CO2-heavy oil systems, while the binary interaction parameters (BIPs) are tuned with the experimentally measured saturation pressures. The diffusion coefficient of hot CO2 in heavy oil is then determined once the discrepancy between the experimentally measured dynamic swelling factors and theoretically calculated ones has been minimized. During the diffusion experiments, heat transfer is found to be dominant over mass transfer at the beginning and reach its equilibrium in a shorter time; subsequently, mass transfer shows its dominant effect. The enhanced oil swelling mainly occurs during the coupled heat and mass transfer stage. CO2 diffusion coefficient in heavy oil is found to increase with temperature at a given pressure, while it can be explicitly correlated as a function of temperature.

scholarly journals Heat and mass transfer coefficients and modeling of infrared drying of banana slices

Revista CERES ◽  
2017 ◽  
Vol 64 (5) ◽  
pp. 457-464 ◽  
Author(s):  
Fernanda Machado Baptestini ◽  
Paulo Cesar Corrêa ◽  
Gabriel Henrique Horta de Oliveira ◽  
Fernando Mendes Botelho ◽  
Ana Paula Lelis Rodrigues de Oliveira
Keyword(s):  
Mass Transfer ◽  
Diffusion Coefficient ◽  
Shelf Life ◽  
Heat And Mass Transfer ◽  
Effective Diffusion Coefficient ◽  
Effective Diffusion ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Infrared Drying ◽  
Ripening Stages

ABSTRACT Banana is one of the most consumed fruits in the world, having a large part of its production performed in tropical countries. This product possesses a wide range of vitamins and minerals, being an important component of the alimentation worldwide. However, the shelf life of bananas is short, thus requiring procedures to prevent the quality loss and increase the shelf life. One of these procedures widely used is drying. This work aimed to study the infrared drying process of banana slices (cv. Prata) and determine the heat and mass transfer coefficients of this process. In addition, effective diffusion coefficient and relationship between ripening stages of banana and drying were obtained. Banana slices at four different ripening stages were dried using a dryer with infrared heating source with four different temperatures (65, 75, 85, and 95 ºC). Midilli model was the one that best represented infrared drying of banana slices. Heat and mass transfer coefficients varied, respectively, between 46.84 and 70.54 W m-2 K-1 and 0.040 to 0.0632 m s-1 for temperature range, at the different ripening stages. Effective diffusion coefficient ranged from 1.96 to 3.59 × 10-15 m² s-1. Activation energy encountered were 16.392, 29.531, 23.194, and 25.206 kJ mol-1 for 2nd, 3rd, 5th, and 7th ripening stages, respectively. Ripening stages did not affect the infrared drying of bananas.

Simulation of Drying Behavior of Cotton Bobbins by a Simultaneous Heat and Mass Transfer Model

2011 ◽  
Vol 312-315 ◽  
pp. 854-859
Author(s):  
Ugur Akyol ◽  
Kamil Kahveci ◽  
Ahmet Cihan ◽  
Dinçer Akal
Keyword(s):  
Mass Transfer ◽  
Diffusion Coefficient ◽  
Heat And Mass Transfer ◽  
Textile Industry ◽  
Moisture Ratio ◽  
Transfer Model ◽  
Mass Transfer Model ◽  
Air Temperatures ◽  
Drying Behavior ◽  
Simultaneous Heat

In this study, the drying process of cotton bobbins for different drying air temperatures has been simulated by a simultaneous heat and mass transfer model. In the model, the mass transfer is assumed to be controlled by diffusion. In order to make the simulation, firstly, drying behavior of cotton bobbins for different drying air temperatures has been determined on an experimental bobbin dryer setup which was designed and manufactured based on hot-air bobbin dryers used in textile industry. In the experimental setup, temperatures of different points in cotton bobbins were measured by thermocouples placed inside the bobbins, and weights of the bobbins during the drying period were determined by means of a load cell. Then, moisture ratio and temperature values of the model have been fitted to the experimental ones. The fit was performed by selecting the values for the diffusion coefficient and the thermal diffusivity in the model in such a way that these values make the sum of the squared differences between the experimental and the model results for moisture ratio and temperature minimum. Results show that there is a good agreement between the model results and the experimental measurements. The results also show that temperature has a significant effect on mass transfer and the temperature dependence of the diffusion coefficient may be expressed by an Arrhenius type relation.

scholarly journals A macroscale mixture theory analysis of deposition and sublimation rates during heat and mass transfer in dry snow

2015 ◽  
Vol 9 (5) ◽  
pp. 1857-1878 ◽  
Author(s):  
A. C. Hansen ◽  
W. E. Foslien
Keyword(s):  
Thermal Conductivity ◽  
Mass Transfer ◽  
Diffusion Coefficient ◽  
Effective Thermal Conductivity ◽  
Heat And Mass Transfer ◽  
Effective Diffusion ◽  
Mixture Theory ◽  
Temperature Gradients ◽  
Snow Metamorphism ◽  
Sublimation Rates

Abstract. The microstructure of a dry alpine snowpack is a dynamic environment where microstructural evolution is driven by seasonal density profiles and weather conditions. Notably, temperature gradients on the order of 10–20 K m−1, or larger, are known to produce a faceted snow microstructure exhibiting little strength. However, while strong temperature gradients are widely accepted as the primary driver for kinetic growth, they do not fully account for the range of experimental observations. An additional factor influencing snow metamorphism is believed to be the rate of mass transfer at the macroscale. We develop a mixture theory capable of predicting macroscale deposition and/or sublimation in a snow cover under temperature gradient conditions. Temperature gradients and mass exchange are tracked over periods ranging from 1 to 10 days. Interesting heat and mass transfer behavior is observed near the ground, near the surface, as well as immediately above and below dense ice crusts. Information about deposition (condensation) and sublimation rates may help explain snow metamorphism phenomena that cannot be accounted for by temperature gradients alone. The macroscale heat and mass transfer analysis requires accurate representations of the effective thermal conductivity and the effective mass diffusion coefficient for snow. We develop analytical models for these parameters based on first principles at the microscale. The expressions derived contain no empirical adjustments, and further, provide self consistent values for effective thermal conductivity and the effective diffusion coefficient for the limiting cases of air and solid ice. The predicted values for these macroscale material parameters are also in excellent agreement with numerical results based on microscale finite element analyses of representative volume elements generated from X-ray tomography.

scholarly journals A macroscale mixture theory analysis of deposition and sublimation rates during heat and mass transfer in snow

2015 ◽  
Vol 9 (2) ◽  
pp. 1503-1554
Author(s):  
A. C. Hansen ◽  
W. E. Foslien
Keyword(s):  
Thermal Conductivity ◽  
Mass Transfer ◽  
Diffusion Coefficient ◽  
Heat And Mass Transfer ◽  
Effective Diffusion ◽  
Mixture Theory ◽  
Temperature Gradients ◽  
Analytical Models ◽  
Snow Metamorphism ◽  
Sublimation Rates

Abstract. The microstructure of a dry alpine snowpack is a dynamic environment where microstructural evolution is driven by seasonal density profiles and weather conditions. Notably, temperature gradients on the order of 10–20 K m−1, or larger, are known to produce a faceted snow microstructure exhibiting little strength. However, while strong temperature gradients are widely accepted as the primary driver for kinetic growth, they do not fully account for the range of experimental observations. An additional factor influencing snow metamorphism is believed to be the rate of mass transfer at the macroscale. We develop a mixture theory capable of predicting macroscale deposition and/or sublimation in a snow cover under temperature gradient conditions. Temperature gradients and mass exchange are tracked over periods ranging from 1 to 10 days. Interesting heat and mass transfer behavior is observed near the ground, near the surface, as well as immediately above and below dense ice crusts. Information about deposition (condensation) and sublimation rates may help explain snow metamorphism phenomena that cannot be accounted for by temperature gradients alone. The macroscale heat and mass transfer analysis requires accurate representations of the thermal conductivity and the effective mass diffusion coefficient for snow. We develop analytical models for these parameters based on first principles at the microscale. The expressions derived contain no empirical adjustments, and further, provide self consistent values for thermal conductivity and the effective diffusion coefficient for the limiting cases of air and solid ice. The predicted values for these macroscale material parameters are also in excellent agreement with numerical results based on microscale finite element analyses of representative volume elements generated from X-ray tomography.

The Influence of Vapor Attachment Kinetics on Snow Effective Properties

2021 ◽  
Author(s):  
Kevin Fourteau ◽  
Florent Domine ◽  
Pascal Hagenmuller
Keyword(s):  
Mass Transfer ◽  
Diffusion Coefficient ◽  
Water Vapor ◽  
Heat And Mass Transfer ◽  
Surface Kinetics ◽  
Fast Kinetics ◽  
Vapor Diffusion ◽  
Water Vapor Diffusion ◽  
Effective Coefficients ◽  
The Impact

<p>Proper modelling of heat and mass transfer in snow is a prerequisite for understanding snow metamorphism and simulating the mass and energy budget of a snowpack and the underlying ground. The transfer of heat and water vapor in snow can be described with macroscopic conservation equations, which include effective coefficients such as the snow thermal conductivity or the snow water vapor diffusion coefficient. Here, we investigate the impact of the surface kinetics of water vapor sublimation and deposition at the microscopic scale on these macroscopic equations, restraining ourselves to the limiting cases of slow and fast kinetics. In particular, we show that under the assumption of fast kinetics the thermal behavior of snow is similar to that of a regular inert medium, but with an enhanced conduction in the pores, due to latent heat transported with water vapor. Besides, faster kinetics increases the effective water vapor diffusion coefficient, which nonetheless remains less than that in free air. M<span>ost (but not all) available experimental investigations suggest that in snow, fast surface kinetics prevails, so that our results have numerous implications for the proper simulation of heat and mass transfer in snow.</span></p>

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