Modeling the Thermally Governed Transient Flow Surges in Multitube Condensing Flow Systems With Thermal and Flow Distribution Asymmetry

1989 ◽  
Vol 111 (3) ◽  
pp. 786-791 ◽  
Author(s):  
G. L. Wedekind ◽  
B. L. Bhatt
Keyword(s):  
Flow Rate ◽  
Transient Flow ◽  
Liquid Flow Rate ◽  
Flow Distribution ◽  
Vapor Flow ◽  
Tube Model ◽  
Condenser Tube ◽  
Tube System ◽  
Tube Type ◽  
Complete Condensation

In a tube-type condenser involving complete condensation, small changes in the inlet vapor flow rate momentarily cause very large transient surges in the outlet liquid flow rate. An equivalent single-tube model is proposed that predicts these transient flow surges for a multitube system. The model, based upon a system mean void fraction model developed earlier, includes the effects of thermal and flow distribution asymmetry associated with each individual condenser tube in the multitube system. Theoretical and experimental verification for a two-tube system is presented.

Modeling the Characteristics of Thermally Governed Transient Flow Surges in Multitube Two-Phase Condensing Flow Systems With Compressibility and Thermal and Flow Distribution Asymmetry

1997 ◽  
Vol 119 (3) ◽  
pp. 534-543 ◽  
Author(s):  
G. L. Wedekind ◽  
C. J. Kobus ◽  
B. L Bhatt
Keyword(s):  
Flow Rate ◽  
Transient Flow ◽  
Flow Distribution ◽  
Vapor Flow ◽  
Complex Flow ◽  
Two Phase ◽  
Physical Mechanisms ◽  
Tube Type ◽  
Design Perspective ◽  
Spreadsheet Software

In a tube-type condenser involving complete condensation, small changes in the inlet vapor flow rate momentarily cause very large transient surges in the outlet mass flow rate. An Equivalent Single-Tube Model (ESTM), based on the System Mean Void Fraction Model, is developed that predicts these transient flow surges for a multitube system; including the effects of compressibility as well as thermal and flow distribution asymmetry. The model is verified theoretical and experimentally. From a design perspective, the significant value of the ESTM is that it includes the primary physical mechanisms involved in such complex flow transients, yet is simple enough to be solved on typical “spreadsheet” software.

An Experimental and Theoretical Investigation Into Thermally Governed Transient Flow Surges in Two-Phase Condensing Flow

1977 ◽  
Vol 99 (4) ◽  
pp. 561-567 ◽  
Author(s):  
G. L. Wedekind ◽  
B. L. Bhatt
Keyword(s):  
Experimental Data ◽  
Transient Flow ◽  
Vapor Flow ◽  
Transient Phenomenon ◽  
Two Phase ◽  
Subcooled Liquid ◽  
Measured Flow ◽  
Tube Type ◽  
Complete Condensation ◽  
Small Change

The specific transient phenomenon under consideration is the outlet flowrate of subcooled liquid from a tube-type condenser where complete condensation takes place. Experimental data are presented which indicates that a small change in the inlet vapor flow-rate will momentarily cause a very large transient surge in the outlet flowrate of subcooled liquid. These experimentally measured flow transients are predicted quite accurately using a system mean void fraction model. Also, some preliminary results are presented which indicate the influence of throttling at the condenser outlet as a means of attenuating the transient overshoot characteristics.

An Investigation Into the Effect of Subcooled Liquid Inertia on Flow-Change-Induced Transient Flow Surges in Horizontal Condensing Flow Systems

2005 ◽  
Vol 127 (11) ◽  
pp. 1280-1284 ◽  
Author(s):  
C. J. Kobus
Keyword(s):  
Flow Rate ◽  
Large Scale ◽  
Transient Flow ◽  
Phase Region ◽  
Complex Nature ◽  
Vapor Flow ◽  
Two Phase ◽  
Subcooled Liquid ◽  
Flow Systems ◽  
Final Steady State

The objective of this research is to investigate large-scale transient flow surges of the condensate leaving in-tube condensing flow systems because of perturbations in the inlet vapor flow rate, and the influence of the subcooled liquid inertia of the condensate on these transient responses. Small changes in the inlet vapor flow rate momentarily cause large transient flow surges in the outlet liquid flow rate. Condensate inertia is seen to destabilize the system into an underdamped behavior where the flow rate can overshoot the final steady-state position several times. A one-dimensional, two-fluid, distributed parameter system mean void fraction (SMVF) model of the time-dependent distribution of liquid and vapor within the two-phase region is developed for predicting these transient characteristics, which it is seen to do quite well, especially when consideration is given to the complex nature of the problem.

Onset of Water Hammer Phenomenon Following Flow Surge Characteristics in Tube-Type Condensing Flows

2003 ◽  
Author(s):  
B. L. Bhatt
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Liquid Flow Rate ◽  
Density Ratio ◽  
Water Hammer ◽  
Phase Region ◽  
Bubble Collapse ◽  
Vapor Flow ◽  
Two Phase ◽  
Condensing Flows

Two-Phase region, in condensing flow undergoing complete condensation inside a tube, acts as an amplifier of any small internal or external disturbances. A small, externally imposed change in the inlet vapor flow rate, or heat flux, leads to substantial surges in the outlet liquid flow rate, including the possibility of flow reversals. Also, if the conditions are right, slight internal disturbances as a result of vapor/liquid interaction, can lead to sustained oscillations of large amplitude, such as in the outlet liquid flow rate. Such surging characteristics coupled with rapid bubble collapse may lead to water hammer phenomenon. This paper will summarize both experimental observations and theoretical models as a result of externally imposed, or internally induced, flow changes in condensing flows. The physics of the processes, including liquid/vapor density ratio, vapor compressibility, bubble collapse, and liquid inertia will be highlighted. The condensing flow stability criterion will be used to provide a possible physical and an analytical basis for the catastrophic piping failure due to a condensation induced water hammer.

An Investigation Into the Effect of Subcooled Liquid Inertia on Flowrate Induced Transient Flow Surges in Horizontal Condensing Flow Systems

2003 ◽  
Author(s):  
Chris J. Kobus
Keyword(s):  
Experimental Data ◽  
Large Scale ◽  
Transient Flow ◽  
Salient Feature ◽  
Analytical Tool ◽  
Predictive Capability ◽  
Subcooled Liquid ◽  
Flow Systems ◽  
Tube Type ◽  
Complete Condensation

The objective of this research is to investigate large-scale transient flow surges of condensate leaving horizontal in-tube condensing flow systems, due to perturbations in the inlet vapor flowrate, and the influence of the subcooled condensate inertia on these surges. In a tube-type condenser involving complete condensation, it has been seen that small changes in the inlet vapor flowrate momentarily cause large transient flow surges in the outlet liquid flowrate. A System Mean Void Fraction (SMVF) Model is developed for predicting these flow surge characteristics. Experimental data are also presented, showing both the influence of subcooled liquid inertia, and the very good predictive capability of the SMVF Model. The salient feature of the SMVF Model is its simplicity that, with an experimentally verified predictive capability, enhances the models’ utility as an analytical tool as well as a tool for educational purposes.

Effect of draft tube diameter on nitrogen removal from domestic sewage in a draft tube type reactor

1998 ◽  
Vol 38 (1) ◽  
pp. 319-326
Author(s):  
Taku Fujiwara ◽  
Iso Somiya ◽  
Hiroshi Tsuno ◽  
Yoshio Okuno
Keyword(s):  
Flow Rate ◽  
Nitrogen Removal ◽  
Draft Tube ◽  
Domestic Sewage ◽  
Tube Diameter ◽  
Continuous Treatment ◽  
Anoxic Zone ◽  
Type Reactor ◽  
Tube Type ◽  
Volumetric Loading

The effect of the ratio of draft tube diameter to reactor diameter (Di/Do) on the efficiency of nitrogen removal from domestic sewage is discussed based on liquid-circulating flow rate and continuous treatment data. More than 2.5 minutes of circulation time in the annulus part, which is required to create an anoxic zone, could be maintained under operating conditions in which air flow rate per reactor volume was 2 m3/(m3 · hr) and Di/Do was 0.19. When Di/Do was set at 0.19, the average total organic carbon (TOC), total nitrogen (TN) and dissolved nitrogen (DN) removal efficiencies were 83.2%, 72.1% and 71.6%, respectively, which were higher than those when Di/Do was at 0.26 or 0.36. From these results, it is concluded that 0.19 is the best Di/Do for nitrogen removal in a draft-tube type reactor with an effective depth of 4.0m under the treatment condition in which the BOD volumetric loading rate is in the range 0.22 to 0.46 kgBOD/(m3 · day). More than 80% nitrification and denitrification efficiencies can be achieved simultaneously when both conditions, the aerobic zone ratio being more than 0.2, and the anoxic zone ratio being more than 0.3, are satisfied.

Absorption of oxygen into solutions of polymers

1986 ◽  
Vol 51 (10) ◽  
pp. 2127-2134 ◽  
Author(s):  
František Potůček ◽  
Jiří Stejskal
Keyword(s):  
Mass Transfer ◽  
Aqueous Solutions ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Flow Rate ◽  
Liquid Flow ◽  
Flow Curve ◽  
Liquid Flow Rate ◽  
Polymer Concentration ◽  
Newtonian Liquids

Absorption of oxygen into water and aqueous solutions of poly(acrylamides) was studied in an absorber with a wetted sphere. The effects of changes in the liquid flow rate and the polymer concentration on the liquid side mass transfer coefficient were examined. The results are expressed by correlations between dimensionless criteria modified for non-Newtonian liquids whose flow curve can be described by the Ostwald-de Waele model.

Research on an axial-mounted dual magnetostrictive material rods-based electro-hydrostatic actuator

2021 ◽  
pp. 1045389X2110145
Author(s):  
Yuchuan Zhu ◽  
Chang Liu ◽  
Yunze Song ◽  
Long Chen ◽  
Yulei Jiang ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Flow Rate ◽  
Flow Distribution ◽  
Maximum Flow ◽  
Magnetostrictive Material ◽  
Simulation Techniques ◽  
Motion State ◽  
New Type ◽  
Output Characteristics ◽  
Active Rectification

In this paper, an electro-hydrostatic actuator driven by dual axial-mounted magnetostrictive material rods-based pumps (MMPs) with a new type of active rectification valve is designed in the current study. Based on flow distribution of the active rectification valve and driving energy provided by two MMPs, the actuator can output continuous and bidirectional displacement. By establishing a mathematical model of the actuating system, using simulation techniques, the change rule of hydraulic cylinder’s motion state caused by different driving signals are studied and analyzed. Test equipment platform is constructed in the laboratory to test the output characteristics and confirm the feasibility of the new concept. The experimental results indicate that the maximum flow rate can reach approximately 2.7 L·min−1, while the operating frequency is 180 Hz.

scholarly journals Effects of water salinity on the foam dynamics for EOR application

2021 ◽  
Author(s):  
Svetlana Rudyk ◽  
Sami Al-Khamisi ◽  
Yahya Al-Wahaibi
Keyword(s):  
Flow Rate ◽  
Liquid Flow ◽  
Apparent Viscosity ◽  
Liquid Flow Rate ◽  
Salinity Range ◽  
Porous System ◽  
Foam Formation ◽  
Total Flow ◽  
Total Flow Rate ◽  
Foam Flow

AbstractFactors limiting foam injection for EOR application are exceptionally low rock permeability and exceedingly high salinity of the formation water. In this regard, foam formation using internal olefin sulfonate is investigated over a wide salinity range (1, 5, 8, 10, and 12% NaCl) through 10 mD limestone. The relationships between pressure drop (dP), apparent viscosity, liquid flow rate, total flow rate, salinity, foam texture, and length of foam drops at the outlet used as an indicator of viscosity are studied. Foaming is observed up to 12% NaCl, compared to a maximum of 8% NaCl in similar core-flooding experiments with 50 mD limestone and 255 mD sandstone. Thus, the salinity limit of foam formation has increased significantly due to the low permeability, which can be explained by the fact that the narrow porous system acts like a membrane with smaller holes. Compared to the increasing dP reported for highly permeable rocks, dP linearly decreases in almost the entire range of gas fraction (fg) at 1–10% NaCl. As fg increases, dP at higher total flow rate is higher at all salinities, but the magnitude of dP controls the dependence of apparent viscosity on total flow rate. Low dP is measured at 1% and 10% NaCl, and high dP is measured at 5, 8, and 12% NaCl. In the case of low dP, the apparent viscosity is higher at higher total flow rate with increasing gas fraction, but similar at two total flow rates with increasing liquid flow rate. In the case of high dP, the apparent viscosity is higher at lower total flow rate, both with an increase in the gas fraction and with an increase in the liquid flow rate. A linear correlation is found between dP or apparent viscosity and liquid flow rate, which defines it as a governing factor of foam flow and can be considered when modeling foam flow.

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