scholarly journals Validation of the generalized model of two-phase thermosyphon loop based on experimental measurements of volumetric flow rate

2016 ◽  
Vol 37 (3) ◽  
pp. 109-138 ◽  
Author(s):  
Henryk Bieliński
Keyword(s):  
Steady State ◽  
Flow Rate ◽  
Vertical Section ◽  
Volumetric Flow Rate ◽  
Working Fluid ◽  
Two Phase ◽  
Generalized Model ◽  
Flow Models ◽  
Theoretical Predictions ◽  
The One

AbstractThe current paper presents the experimental validation of the generalized model of the two-phase thermosyphon loop. The generalized model is based on mass, momentum, and energy balances in the evaporators, rising tube, condensers and the falling tube. The theoretical analysis and the experimental data have been obtained for a new designed variant. The variant refers to a thermosyphon loop with both minichannels and conventional tubes. The thermosyphon loop consists of an evaporator on the lower vertical section and a condenser on the upper vertical section. The one-dimensional homogeneous and separated two-phase flow models were used in calculations. The latest minichannel heat transfer correlations available in literature were applied. A numerical analysis of the volumetric flow rate in the steady-state has been done. The experiment was conducted on a specially designed test apparatus. Ultrapure water was used as a working fluid. The results show that the theoretical predictions are in good agreement with the measured volumetric flow rate at steady-state.

Experimental, Numerical, and Statistical Investigation of Two Phase Flow in a Cylindrical Perforation Tunnel

2021 ◽  
Author(s):  
Ekhwaiter Abobaker ◽  
Abadelhalim Elsanoose ◽  
Mohammad Azizur Rahman ◽  
Faisal Khan ◽  
Amer Aborig ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Steady State ◽  
Statistical Analysis ◽  
Flow Rate ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Gas Flow Rate ◽  
Two Phase ◽  
Flow Through

Abstract Perforation is the final stage in well completion that helps to connect reservoir formations to wellbores during hydrocarbon production. The drilling perforation technique maximizes the reservoir productivity index by minimizing damage. This can be best accomplished by attaining a better understanding of fluid flows that occur in the near-wellbore region during oil and gas operations. The present work aims to enhance oil recovery by modelling a two-phase flow through the near-wellbore region, thereby expanding industry knowledge about well performance. An experimental procedure was conducted to investigate the behavior of two-phase flow through a cylindrical perforation tunnel. Statistical analysis was coupled with numerical simulation to expand the investigation of fluid flow in the near-wellbore region that cannot be obtained experimentally. The statistical analysis investigated the effect of several parameters, including the liquid and gas flow rate, liquid viscosity, permeability, and porosity, on the injection build-up pressure and the time needed to reach a steady-state flow condition. Design-Expert® Design of Experiments (DoE) software was used to determine the numerical simulation runs using the ANOVA analysis with a Box-Behnken Design (BBD) model and ANSYS-FLUENT was used to analyses the numerical simulation of the porous media tunnel by applying the volume of fluid method (VOF). The experimental data were validated to the numerical results, and the comparison of results was in good agreement. The numerical and statistical analysis demonstrated each investigated parameter’s effect. The permeability, flow rate, and viscosity of the liquid significantly affect the injection pressure build-up profile, and porosity and gas flow rate substantially affect the time required to attain steady-state conditions. In addition, two correlations obtained from the statistical analysis can be used to predict the injection build-up pressure and the required time to reach steady state for different scenarios. This work will contribute to the clarification and understanding of the behavior of multiphase flow in the near-wellbore region.

Factors Affecting Oil Removal From an Aeroengine Bearing Chamber

2010 ◽  
Author(s):  
Budi Chandra ◽  
Kathy Simmons ◽  
Stephen Pickering ◽  
Marc Tittel
Keyword(s):  
Heat Generation ◽  
Volumetric Flow Rate ◽  
Volume Measurement ◽  
Working Fluid ◽  
Liquid Volume ◽  
Simple Liquid ◽  
Oil Removal ◽  
Two Phase ◽  
Ongoing Research ◽  
Excessive Heat

Aeroengines incorporate various bearing chambers that house the shaft bearings and the oil used to cool and lubricate these bearings must subsequently be recovered from these chambers. Effective oil removal (scavenge) is essential to avoid heat generation through unnecessary working of the oil which can lead to excessive heat generation and reduced overall efficiency. Therefore the design of the scavenge region (sump) in a bearing chamber, as well as the ability to assess its performance is very important. An ongoing research program into bearing chamber scavenge comprising experimental and computational components is being conducted at the University of Nottingham Technology Centre in Gas Turbine Transmission Systems. This program is enhancing understanding of sump performance and design. In this paper an experimental study into a simplified but representative scavenge is reported. This experimental work helps to further understanding of the complex two-phase flow physics in a bearing chamber, particularly in the scavenge region, by means of various measurements and flow visualization. For the study a bespoke test rig has been built. It consists of a simplified, generic bearing chamber with simple sump geometry constructed entirely of Perspex to allow visualization. A shaft in the centre of the chamber capable of rotating up to 15,000 rpm is employed to introduce a windage flow in the chamber. Water (the working fluid) is fed to the chamber via an inlet pump and an outlet pump removes liquid from the chamber, closing the circuit. Several pneumatic pinch valves are installed in the flow circuit to allow residence volume measurement. A completely air-tight reservoir with internal baffle functions as a simple liquid-gas separator, allowing measurement of gas volumetric flow rate in the off-take pipe; hence the scavenge ratio (ratio of total exit volume to liquid volume) can be obtained. Residence volume measurements highlight the importance of sump geometry as an ill-designed sump can lead to an undesirable increase in residence volume.

Verification of a One-Dimensional Two-Phase Flow Model of the Frontal Gap in Electrochemical Machining

1976 ◽  
Vol 98 (2) ◽  
pp. 431-437 ◽  
Author(s):  
F. Fluerenbrock ◽  
R. D. Zerkle ◽  
J. F. Thorpe
Keyword(s):  
Flow Model ◽  
Radial Flow ◽  
Electrochemical Machining ◽  
Equilibrium Conditions ◽  
Two Phase ◽  
One Dimensional ◽  
Supply Pressure ◽  
Theoretical Predictions ◽  
The One ◽  
Experimental Pressure

A set of six equations, which are based on the ECM model developed by Thorpe and Zerkle, can be solved numerically to yield the one-dimensional distributions of pressure, temperature, gas density, gap thickness, void fraction, and electrolyte velocity in the rectilinear ECM frontal gap under equilibrium conditions. The validity of the model, which also applies to radial flow geometries, is confirmed by comparing experimental pressure and gap profiles with theoretical predictions. It is shown that for a given set of operating parameters there is a minimum supply pressure below which no machining is possible. When machining steel with an aqueous NaCl electrolyte the deposition of a black smut (Fe(OH)2) occurs beyond a certain smut-free entrance length, which was experimentally found to be proportional to the inlet gap thickness.

A 3D Transient Model for the Multiphase Flow in a Progressing-Cavity Pump

SPE Journal ◽  
2016 ◽  
Vol 21 (04) ◽  
pp. 1458-1469 ◽  
Author(s):  
Victor W. de Azevedo ◽  
João A. de Lima ◽  
Emilio E. Paladino
Keyword(s):  
Multiphase Flow ◽  
Flow Rate ◽  
Homogeneous Model ◽  
Volumetric Flow Rate ◽  
Volumetric Efficiency ◽  
Two Phase ◽  
Transient Model ◽  
Viscous Losses ◽  
Constant Displacement ◽  
Gas Volume

Summary This paper presents the development of a computational-fluid-dynamics (CFD) model for the 3D transient two-phase flow within a progressing-cavity pump (PCP). The model implementation was only possible because of the meticulous mesh-generation and mesh-motion algorithm, previously published by the authors, which is briefly described herein. In this algorithm, a structured mesh was generated by defining all nodes’ positions and connectivities, for each rotor position by means of FORTRAN subroutines, which were embodied into ANSYS CFX software. The model is capable of predicting accurately the volumetric efficiency and the viscous losses, and it provides detailed information of pressure and velocity fields and void distribution along the pump. Such information could be of fundamental importance for product development and/or optimization for field operation. In field applications, the common situation is that in which the oil comes into the pump accompanied with free gas, which characterizes a multiphase flow. Simplified models on the basis of the calculation of the backflow or “slippage,” which is subtracted from the displaced flow rate, fail to characterize the PCP performance under multiphase conditions because the slip is variable along the pump. In this model, the governing equations were solved with an element-based finite-volume method in a moving mesh. The Eulerian-Eulerian approach, considering the homogeneous model, is used to model the flow of the gas/liquid mixture. The compressibility of the gas is taken into account, which is one of the main shortcomings in positive/constant displacement pumps. The effects of the different gas-volume fractions (GVFs) in pump volumetric efficiency, pressure distribution, power, slippage flow rate, and volumetric flow rate were analyzed, and some new insights are presented about the slippage in PCPs operating in multiphase conditions. The results show that the developed model is capable of reproducing pump dynamic behavior under multiphase-flow conditions performed early in experimental works.

An Experimental Study of Two Phase Flow in Impinging Micro Channels

2013 ◽  
Author(s):  
Liang-Han Chien ◽  
Han-Yang Liu ◽  
Wun-Rong Liao
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flow Rate ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Experimental Result ◽  
Working Fluid ◽  
Transfer Performance ◽  
Two Phase ◽  
Micro Channels

A heat sink integrating micro-channels with multiple jets was designed to achieve better heat transfer performance for chip cooling. Dielectric fluid FC-72 was the working fluid. The heat sink contained 11 micro-channels, and each channel was 0.8 mm high, 0.6 mm wide, and 12 mm in length. There were 3 or 5 pores on each micro-channel. The pore diameters were either 0.24 or 0.4 mm, and the pore spacing ranged from 1.5 to 3 mm. In the tests, the saturation temperature of cooling device was set at 30 and 50°C, and the volume flow rate ranged from 9.1 to 73.6 ml/min per channel (total flow rate = 100∼810 ml/min). The experimental result showed that heat transfer performance increased with increasing flow rate for single phase heat transfer. For heat flux between 20 and 100 kW/m2, the wall superheat decreases with increasing flow rate at a fixed heat flux. However, the influence of the flow rate diminished when the channels are in two phase heat transfer regime. Except for the lowest flow rate (9.1 ml/min), the heat transfer performance increased with increasing jet diameter/spacing ratios. The best surface had three nozzles of 0.4 mm diameter in 3.0 mm jet spacing. It had the lowest thermal resistance of 0.0611 K / W in the range of 200 ∼ 240 W heat input.

A Comparative Study of Single-Phase, Two-Phase, and Supercritical Natural Circulation in a Rectangular Loop

2010 ◽  
Vol 132 (10) ◽  
Author(s):  
P. K. Vijayan ◽  
M. Sharma ◽  
D. S. Pilkhwal ◽  
D. Saha ◽  
R. K. Sinha
Keyword(s):  
Steady State ◽  
Flow Rate ◽  
Significant Influence ◽  
Single Phase ◽  
Natural Circulation ◽  
Phase Region ◽  
Inlet Temperature ◽  
Two Phase ◽  
Supercritical Region ◽  
Stability Performance

A one-dimensional theoretical model has been used to analyze the steady state and stability performance of a single-phase, two-phase, and supercritical natural circulation in a uniform diameter rectangular loop. Parametric influences of diameter, inlet temperature, and system pressure on the steady state and stability performance have been studied. In the single-phase liquid filled region, the flow rate is found to increase monotonically with power. On the other hand, the flow rate in two-phase natural circulation systems is found to initially increase, reach a peak, and then decrease with power. For the supercritical region also, the steady state behavior is found to be similar to that of the two-phase region. However, if the heater inlet temperature is beyond the pseudo critical value, then the performance is similar to single-phase loops. Also, the supercritical natural circulation flow rate decreases drastically during this condition. With an increase in loop diameter, the flow rate is found to enhance for all the three regions of operation. Pressure has a significant influence on the flow rate in the two-phase region, marginal effect in the supercritical region, and practically no effect in the single-phase region. With the increase in loop diameter, operation in the single-phase and supercritical regions is found to destabilize, whereas the two-phase loops are found to stabilize. Again, pressure has a significant influence on stability in the two-phase region.

A Comparative Study of Single-Phase, Two-Phase and Supercritical Natural Circulation in a Rectangular Loop

2009 ◽  
Author(s):  
P. K. Vijayan ◽  
D. S. Pilkhwal ◽  
M. Sharma ◽  
D. Saha ◽  
R. K. Sinha
Keyword(s):  
Steady State ◽  
Flow Rate ◽  
Significant Influence ◽  
Single Phase ◽  
Natural Circulation ◽  
Phase Region ◽  
Inlet Temperature ◽  
Two Phase ◽  
Supercritical Region ◽  
Stability Performance

A one dimensional theoretical model has been used to analyze the steady state and stability performance of single-phase, two-phase and supercritical natural circulation in a uniform diameter rectangular loop. Parametric influences of diameter, inlet temperature and system pressure on the steady state and stability performance has been studied. In the single-phase liquid filled region, the flow rate is found to increase monotonically with power. On the other hand the flow rate in two-phase NCS is found to initially increase, reach a peak and then decrease with power. For the supercritical region also, the steady state behaviour is found to be similar to that of two-phase region. However, if the heater inlet temperature is beyond the pseudo critical value, then the performance is similar to single-phase loops. Also, the supercritical natural circulation flow rate decreases drastically during this condition. With increase in loop diameter, the flow rate is found to enhance for all the three regions of operation. Pressure has a significant influence on flow rate in two-phase region marginal effect in supercritical region and practically no effect in the single-phase region. With increase in loop diameter, operation in the single-phase and supercritical regions is found to destabilize whereas the two-phase loops are found to stabilize. Again, pressure has a significant influence on stability in the two-phase region.

Rotordynamic Coefficients for a Tooth-on-Stator Labyrinth Seal at 70 Bar Supply Pressures: Measurements Versus Theory and Comparisons to a Hole-Pattern Stator Seal

2004 ◽  
Vol 127 (4) ◽  
pp. 843-855 ◽  
Author(s):  
Arthur Picardo ◽  
Dara W. Childs
Keyword(s):  
Control Volume ◽  
Labyrinth Seal ◽  
Test Results ◽  
Flow Models ◽  
Rotordynamic Coefficients ◽  
Volume Model ◽  
Supply Pressure ◽  
Theoretical Predictions ◽  
The One ◽  
Rotor Dynamic

Rotor dynamic and leakage coefficients are presented for a labyrinth seal that was tested at a supply pressure of 70 bar-a and speeds up to 20,200 rpm. Tests were conducted at clearances of 0.1 mm and 0.2 mm, pressure ratios of 0.10, 0.31, and 0.52, and three preswirls ratios. Comparisons are made between test data and predictions from one-control-volume and two-control-volume bulk-flow models. Generally, theoretical predictions agree poorly with the test results, with the one-control volume model giving better predictions. The one-control-volume model provides a conservative prediction for effective damping; i.e., this parameter is underestimated. Both models under predict leakage rates. Comparisons are also made between rotordynamic coefficients of labyrinth and hole-pattern seals.

Rotordynamic Coefficients for a Tooth-on-Stator Labyrinth Seal at 70 Bar Supply Pressures — Measurements Versus Theory and Comparisons to a Hole-Pattern Stator Seal

2004 ◽  
Author(s):  
Arthur Picardo ◽  
Dara W. Childs
Keyword(s):  
Test Data ◽  
Control Volume ◽  
Labyrinth Seal ◽  
Test Results ◽  
Flow Models ◽  
Rotordynamic Coefficients ◽  
Volume Model ◽  
Supply Pressure ◽  
Theoretical Predictions ◽  
The One

Rotordynamic and leakage coefficients are presented for a labyrinth seal that was tested at a supply pressure of 70 bar-a and speeds up to 20200 rpm. Tests were conducted at clearances of 0.1mm and 0.2mm, pressure ratios of 0.10, 0.31 and 0.52, and three pre-swirls ratios. Comparisons are made between test data and predictions from one-control-volume and two-control-volume bulk-flow models. Generally, theoretical predictions agree poorly with the test results, with the one-control volume model giving better predictions. The one-control-volume model provides a conservative prediction for effective damping; i.e., this parameter is underestimated. Both models under predict leakage rates. Comparisons are also made between rotordynamic coefficients of labyrinth and hole-pattern seals.

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