Simulation of Gas-Hydrate Slurry Stratified Flow With Inward and Outward Hydrate Growth Model

2016 ◽  
Author(s):  
Bohui Shi ◽  
Yang Liu ◽  
Lin Ding ◽  
Xiaofang Lv ◽  
Jing Gong
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Liquid Phase ◽  
Shell Model ◽  
Gas Hydrate ◽  
Hydrodynamic Model ◽  
Formation Rate ◽  
Hydrate Formation ◽  
Phase Flow ◽  
Two Phase

The topic of hydrate formation and blocking in offshore petroleum industry has attracted more and more attentions, which is known as one of the flow assurance issues. A new technology has been proposed to avoid the occurrence of hydrate blockage in multiphase transportation system, which is hydrate slurry flow technology, also named as cold flow technology. The low dosage hydrate inhibitor of anti-agglomerate was added into the flow systems to allow hydrate formation in the liquid phase while it prevented the aggregation of hydrate particles. Thus these particles were evacuated with the liquid phase as pseudo-fluid like slurry. In this work, an inward and outward hydrate growth shell model coupled with two phase flow hydrodynamic model was applied to investigate the characteristics of gas-hydrate slurry stratified flow. The inward and outward hydrate growth shell model considered the kinetics, mass transfer and heat transfer process of hydrate formation, which could predict the hydrate formation rate and the released heat. The two phase flow hydrodynamic model included mass, momentum and energy equations. A case for an inclined pipeline was simulated using the combined models. The results showed that once the kinetic requirements for hydrate crystallization was satisfied, hydrates would form quickly at the initial stage and then hydrate formation rate would decrease obviously due to the limitation of mass transfer and heat transfer. Meanwhile, the flow characteristics, such as the liquid holdup and pressure drop, were predicted by the model, which also provided an acceptable results about the state of hydrates (onset time of formation, formation rate, volume fraction, etc.) in multiphase system for the operation engineers in the field. The key parameters of the inward and outward hydrate growth shell model were determined by referring to the literatures. To investigate the reliability and influence of these set values on the results, a sensitivity analysis of the key parameters of the shell model was implemented. Further works should be done, such as the flow mechanism in other flow regimes as well as the influence of particle aggregation.

New Simulator for Gas–Hydrate Slurry Stratified Flow Based on the Hydrate Kinetic Growth Model

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Bohui Shi ◽  
Yang Liu ◽  
Lin Ding ◽  
Xiaofang Lv ◽  
Jing Gong
Keyword(s):  
Heat Transfer ◽  
Shell Model ◽  
Gas Hydrate ◽  
Hydrodynamic Model ◽  
Formation Rate ◽  
Hydrate Formation ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Two Phase ◽  
Mass And Heat Transfer

A new simulator for gas–hydrate slurry stratified flow is presented, which can simulate the flow characteristics, including gas/liquid velocity, liquid holdup, and pressure drop. The simulator includes an inward and outward hydrate growth shell model and two-phase flow hydrodynamic model. The hydrate growth model systematically considers the kinetics and limitations of hydrate formation, namely, the mass– and heat–transfer. The two-phase flow hydrodynamic model is composed of mass and momentum equations for each phase as well as energy balance equations considering the heat generation related to hydrate formation. Thereafter, an inclined pipeline case is simulated using the simulator. The results demonstrate that, once the kinetic requirements for hydrate crystallization are satisfied, hydrates form rapidly during the initial stage and the hydrate formation rate then decreases owing to the limitation of the mass– and heat–transfer. Meanwhile, the hydrate states (formation onset time, formation rate, and volume fraction) as well as flow characteristics of a multiphase system are obtained, providing acceptable results for engineers in the field. Sensitivity analyses of the key hydrate growth shell model parameters are implemented, and the results indicate that the influences of diffusivity and initial water droplet size on the hydrate formation rate are greater than the of the porous parameter.

scholarly journals ANALYSIS OF INTERFACIAL AND MASS TRANSFER EFFECTS ON FORCED CONVECTION IN GAS-LIQUID ANNULAR TWO-PHASE FLOW

2004 ◽  
Vol 3 (1) ◽  
pp. 45
Author(s):  
E. Nogueira ◽  
B. D. Dantas ◽  
R. M. Cotta
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Film Thickness ◽  
Liquid Film ◽  
Liquid Film Thickness ◽  
Phase Flow ◽  
Transfer Effects ◽  
Two Phase ◽  
Transfer Rates ◽  
Interface Waves

In a gas-liquid annular two-phase flow one of the main factors influencing the determination of heat transfer rates is the average thickness of the liquid film. A model to accurately represent the heat transfer in such situations has to be able of determining the average liquid film thickness to within a reasonable accuracy. A typical physical aspect in gas-liquid annular flows is the appearance of interface waves, which affect heat, mass and momentum transfers. Existing models implicitly consider the wave effects in the momentum transfer by an empirical correlation for the interfacial friction factor. However, this procedure does not point out the difference between interface waves and the natural turbulent effects of the system. In the present work, the wave and mass transfer effects in the theoretical estimation of average liquid film thickness are analyzed, in comparison to a model that does not explicitly include these effects, as applied to the prediction of heat transfer rates in a thermally developing flow situation.

Two-Phase Flow Heat and Mass Transfer Model Construction and Experiment Study of the Fuel Evaporation Progress

2012 ◽  
Vol 614-615 ◽  
pp. 174-180
Author(s):  
Bo Yun Liu ◽  
Jin Yun Pu ◽  
Xiang Lie Yi
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Two Phase Flow ◽  
Time Dependent ◽  
Transfer Model ◽  
Phase Flow ◽  
Two Phase ◽  
Dependent Behavior ◽  
Mass Evaporation ◽  
Hot Surface

As for the time-dependent behavior of the fuel heat and mass evaporation transfer progress on hot surface,consider the convective mass transfer and heat transfer, the liquid-gas two-phase flow of continuous heat transfer model was studied. By the dimensionless transform, the time-dependent behavior of the concentration distribution and the temperature field was obtained. The result of n-Heptanes evaporation transfer progress on hot surface experiment is consistent with the academic model.

Analytical Simulation of Annular Two-Phase Flow Considering the Four Involved Mass Transfers

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Zahra Baniamerian ◽  
Ramin Mehdipour ◽  
Cyrus Aghanajafi
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Fluid Flow ◽  
Analytical Model ◽  
Two Phase Flow ◽  
Experimental Models ◽  
Analytical Models ◽  
Phase Flow ◽  
Two Phase Flows ◽  
Two Phase

Efficiently employing two-phase flows for cooling objectives requires comprehensive knowledge of their behavior in different conditions. Models, capable of predicting heat transfer and fluid flow trends in this area, are of great value. Numerical/analytical models in the literature are one-dimensional models involving with many simplifying assumptions. These assumptions in most cases include neglecting some mechanisms of mass transfer in two-phase flows. This study is devoted to developing an analytical two-dimensional model for simulation of fluid flow and mass transfer in two-phase flows considering the all mass transfer mechanisms (entrainment, evaporation, deposition and condensation). The correlation employed for modeling entrainment in this study, is a semiempirical correlation derived based on physical concept of entrainment phenomenon. Emphasis is put on the annular flow pattern of liquid vapor two-phase flow since this regime is the last encountered two-phase regime and has a higher heat transfer coefficient among other two-phase flow patterns. Attempts are made to employ the least possible simplification assumptions and empirical correlations in the modeling procedure. The model is then verified with experimental models of Shanawany et al., Stevanovic et al. and analytical model of Qu and Mudawar. It will be shown, considering pressure variations in both radial and axial directions along with applying our semiempirical entrainment correlation has improved the present analytical model accuracy in comparison with the accuracy of available analytical models.

scholarly journals Modeling and Numerical Investigation of Transient Two-Phase Flow with Liquid Phase Change in Porous Media

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 183
Author(s):  
Fei He ◽  
Wenjie Dong ◽  
Jianhua Wang
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Liquid Phase ◽  
Phase Change ◽  
Two Phase Flow ◽  
Transient Heat Transfer ◽  
Phase Flow ◽  
Two Phase ◽  
Heat Transfer Deterioration ◽  
Temperature Structure Parameter

Two-phase flow with phase change in microstructure or nanostructure is an important issue in many fronts and critical applications nowadays, but with a lack of comprehensive understanding of the mechanism. This paper numerically investigates the transient behavior of two-phase flow with liquid phase change in the porous media, which consists of a series of connected pores at micro and nanoscale with the transient form of the semi-mixed model and self-compiled programs. Transient variation and spatial distribution of structure temperature, thermal non-equilibrium characteristic, phase change location and fluid-driven pressure are obtained and analyzed, and effects of initial system temperature, structure parameter and material property on the transient behaviors of two-phase flow and fluid-structure coupling heat transfer are discussed. The numerical simulations indicate that the two-phase flow with phase change in porous media is complex and ever-changing before reaching a steady state and affected by the above-mentioned three kinds of parameters significantly. Particularly, distinct phenomena of transient heat transfer deterioration and vapor block are discovered, and it is revealed that the transient heat transfer deterioration and vapor block are more serious in a porous matrix with smaller porosity and made of materials with higher heat capacity and density.

A Mechanistic Model for Predicting Heat and Mass Transfer in Vertical Two-Phase Flow

Volume 3 ◽  
2004 ◽  
Author(s):  
Siamack A. Shirazi ◽  
Ebrahin Al-Adsani ◽  
John R. Shadley ◽  
Edmund F. Rybicki
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Two Phase Flow ◽  
Mechanistic Model ◽  
Intermittent Flow ◽  
Phase Flow ◽  
Empirical Correlations ◽  
Transfer Coefficients ◽  
Two Phase

The mass transfer coefficient plays an important role in predicting corrosion rates. Using similarities between heat and mass transfer mechanisms, a mechanistic model is proposed to predict heat and mass transfer coefficients for two-phase flow in vertical pipes. The mechanistic model is evaluated by using water-air heat transfer experimental data obtained from the literature. The mechanistic model is also compared with commonly used empirical correlations. In comparison with available heat transfer correlations, the mechanistic model performs very well for vertical annular flow, bubbly flow and slug or intermittent flow that were considered. The mechanistic model is based on physics of two-phase flow and thus is expected to be more general than empirical correlations.

scholarly journals Experimental investigation of heat transfer performance coefficient in tube bundle of shell and tube heat exchanger in two-phase flow

2014 ◽  
Vol 35 (1) ◽  
pp. 87-98 ◽  
Author(s):  
Marcin Karaś ◽  
Daniel Zając ◽  
Roman Ulbrich
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Tube Bundle ◽  
Limiting Current ◽  
Phase Flow ◽  
Two Phase ◽  
Tube Heat Exchanger

Abstract This paper presents the results of studies in two phase gasliquid flow around tube bundle in the model of shell tube heat exchanger. Experimental investigations of heat transfer coefficient on the tubes surface were performed with the aid of electrochemical technique. Chilton-Colburn analogy between heat and mass transfer was used. Twelve nickel cathodes were mounted on the outside surface of one of the tubes. Measurement of limiting currents in the cathodic reduction of ferricyanide ions on nickel electrodes in aqueous solution of equimolar quantities of K3Fe(CN)6 and K4Fe(CN)6 in the presence of NaOH basic solution were applied to determine the mass transfer coefficient. Controlled diffusion from ions at the electrode was observed and limiting current plateau was measured. Measurements were performed with data acquisition equipment controlled by software created for this experiment. Mass transfer coefficient was calculated on the basis of the limiting current measurements. Results of mass transfer experiments (mass transfer coefficient) were recalculated to heat transfer coefficient. During the experiments, simultaneously conducted was the the investigation of two-phase flow structures around tubes with the use of digital particle image velocimetry. Average velocity fields around tubes were created with the use of a number of flow images and compared with the results of heat transfer coefficient calculations.

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