Coupling heat and mass transfer for a gas mixture–heavy oil system at high pressures and elevated temperatures

2014 ◽  
Vol 74 ◽  
pp. 173-184 ◽  
Author(s):  
Huijuan Sun ◽  
Huazhou Li ◽  
Daoyong Yang
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Heavy Oil ◽  
High Pressures ◽  
Elevated Temperatures ◽  
Gas Mixture

Determination of Individual Diffusion Coefficients of C3H8/n-C4H10/CO2/Heavy-Oil Systems at High Pressures and Elevated Temperatures by Dynamic Volume Analysis

SPE Journal ◽  
2016 ◽  
Vol 22 (03) ◽  
pp. 799-816 ◽  
Author(s):  
Sixu Zheng ◽  
Daoyong Yang
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Volume Change ◽  
Heavy Oil ◽  
Diffusion Coefficients ◽  
High Pressures ◽  
Elevated Temperatures ◽  
Transfer Model ◽  
Volume Analysis ◽  
Alkane Solvents

Summary By coupling heat and mass transfer for C3H8/n-C4H10/CO2/heavy-oil systems as well as by treating heavy oil as multiple pseudocomponents, a new technique together with its computational scheme has been developed to determine individual diffusion coefficients of alkane solvents and CO2 in heavy oil at high pressures and elevated temperatures by dynamic volume analysis (DVA). Experimentally, well-designed diffusion tests have been conducted for an n-C4H10/heavy-oil system, a CO2/heavy-oil system, an n-C4H10/CO2/heavy-oil system, and a C3H8/n-C4H10/CO2/heavy-oil system by using a visualized pressure/volume/temperature (PVT) setup. The volume change of liquid phase is monitored and recorded during the measurements, whereas the gas-chromatography (GC) method is used to determine the compositions of gas mixtures at the beginning and the end of the diffusion tests. Theoretically, the volume-translated Peng-Robinson (PR) equation of state (EOS) characterizing heavy oil as multiple pseudocomponents has been incorporated to develop a 2D heat-and-mass-transfer model for the aforementioned systems. The alternating-direction-implicit algorithm is applied to solve the 2D difference equations into which a moving gas/liquid interface has been successfully incorporated. The discrepancy between the measured and calculated dynamic-volume change and the discrepancy between the measured and calculated gas compositions at the end of diffusion tests have been minimized to determine the individual diffusion coefficients. Alkane solvents diffuse faster than CO2 in heavy oil, whereas addition of alkane solvent(s) into the CO2 stream not only enhances mass transfer, but also achieves an improved swelling effect of heavy oil. Among the four diffusion tests, the largest dynamic swelling factor at the end of the diffusion test is measured to be 1.118 for the C3H8/n-C4H10/CO2/heavy-oil system.

scholarly journals Impact of plant shoot architecture on leaf cooling: a coupled heat and mass transfer model

2013 ◽  
Vol 10 (85) ◽  
pp. 20130326 ◽  
Author(s):  
L. J. Bridge ◽  
K. A. Franklin ◽  
M. E. Homer
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Elevated Temperatures ◽  
Saturation Temperature ◽  
Soil Surface ◽  
Cooling Capacity ◽  
Transfer Model ◽  
Basic Model ◽  
Liquid Saturation ◽  
Water Vapour Diffusion

Plants display a range of striking architectural adaptations when grown at elevated temperatures. In the model plant Arabidopsis thaliana , these include elongation of petioles, and increased petiole and leaf angles from the soil surface. The potential physiological significance of these architectural changes remains speculative. We address this issue computationally by formulating a mathematical model and performing numerical simulations, testing the hypothesis that elongated and elevated plant configurations may reflect a leaf-cooling strategy. This sets in place a new basic model of plant water use and interaction with the surrounding air, which couples heat and mass transfer within a plant to water vapour diffusion in the air, using a transpiration term that depends on saturation, temperature and vapour concentration. A two-dimensional, multi-petiole shoot geometry is considered, with added leaf-blade shape detail. Our simulations show that increased petiole length and angle generally result in enhanced transpiration rates and reduced leaf temperatures in well-watered conditions. Furthermore, our computations also reveal plant configurations for which elongation may result in decreased transpiration rate owing to decreased leaf liquid saturation. We offer further qualitative and quantitative insights into the role of architectural parameters as key determinants of leaf-cooling capacity.

scholarly journals Pulsed Multiphase Flows—Numerical Investigation of Particle Dynamics in Pulsating Gas–Solid Flows at Elevated Temperatures

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 815
Author(s):  
Arne Teiwes ◽  
Maksym Dosta ◽  
Michael Jacob ◽  
Stefan Heinrich
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Multiphase Flows ◽  
Gas Flow ◽  
Elevated Temperatures ◽  
Process Intensification ◽  
Particle Dynamics ◽  
Transport Processes ◽  
Pulse Combustion ◽  
New Processing

Although the benefits of pulsating multiphase flows and the concomitant opportunity to intensify heat and mass transfer processes for, e.g., drying, extraction or chemical reactions have been known for some time, the industrial implementation is still limited. This is particularly due to the lack of understanding of basic influencing factors, such as amplitude and frequency of the pulsating flow and the resulting particle dynamics. The pulsation generates oscillation of velocity, pressure, and temperature, intensifying the heat and mass transfer by a factor of up to five compared to stationary gas flow. With the goal of process intensification and targeted control of sub-processes or even the development of completely new processing routes for the formation, drying or conversion of particulate solids in pulsating gas flows as utilized in, e.g., pulse combustion drying or pulse combustion spray pyrolysis, the basic understanding of occurring transport processes is becoming more and more important. In the presented study, the influence of gas-flow conditions and particle properties on particle dynamics as well as particle residence time and the resulting heat and mass transfer in pulsating gas–solid flows are investigated.

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