An investigation into oil—gas two-phase leakage flow through micro gaps in oil-injected compressors

2010 ◽  
Vol 224 (4) ◽  
pp. 925-933
Author(s):  
D Xin ◽  
J Feng ◽  
X Jia ◽  
X Peng
Keyword(s):  
High Speed ◽  
Critical Pressure ◽  
Pressure Ratio ◽  
Volume Ratio ◽  
Flow Patterns ◽  
Leakage Flow ◽  
Two Phase ◽  
Gas Leakage ◽  
Flow Through ◽  
Oil Gas

This article presents the investigation on the oil—gas two-phase leakage flow through the micro gaps in oil-injected compressors and provides a new way of investigating the internal leakage process in the compressors. The oil—gas leakage rates were measured through the micro gaps of various gap sizes, the volume ratios of oil to gas, and pressure differences/ratios; and the flow patterns reflecting the flow characteristics were observed by using a high-speed video. The experimental results showed that the leakage flowrate was significantly related to the flow patterns in the gap, which were similar to those found in the existing literature and agreed well with the predicted ones by the Weber number. The gas leakage flowrate through the gap increased rapidly with the increased pressure ratio until the pressure ratio reached the critical pressure ratio, which ranged from 1.8 to 2.7. At the critical pressure ratio, the flow pattern transition from churn flow to annular flow occurred, resulting in gas leakage driven by a different sealing mechanism. As the volume ratio of oil to gas increased by 0.5 per cent, the gas leakage flowrate decreased by 77 per cent.

The Two-Phase Critical Flow of One-Component Mixtures in Nozzles, Orifices, and Short Tubes

1971 ◽  
Vol 93 (2) ◽  
pp. 179-187 ◽  
Author(s):  
Robert E. Henry ◽  
Hans K. Fauske
Keyword(s):  
Critical Pressure ◽  
Single Phase ◽  
Pressure Ratio ◽  
Stagnation Pressure ◽  
Experimental Results ◽  
Critical Flow ◽  
Two Phase ◽  
Transfer Rates ◽  
Critical Flow Rate ◽  
Flow Through

The critical flow of one-component, two-phase mixtures through convergent nozzles is investigated and discussed including considerations of the interphase heat, mass, and momentum transfer rates. Based on the experimental results of previous investigators, credible assumptions are made to approximate these interphase processes which lead to a transcendental expression for the critical pressure ratio as a function of the stagnation pressure and quality. A solution to this expression also yields a prediction for the critical flow rate. Based on the experimental results of single-phase compressible flow through orifices and short tubes, the two-phase model is extended to include such geometries. The models are compared with steam-water, cryogenic, and alkali-metal experimental data.

Pressure Drop for Oil-Gas Two-Phase Flow Through Straight Horizontal Pipe

2007 ◽  
Author(s):  
Wenhong Liu ◽  
Liejin Guo ◽  
Ximin Zhang ◽  
Kai Lin ◽  
Long Yang ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Flow Through ◽  
Oil Gas

High Speed Imaging and Two-Phase Flow Patterns During Flow Boiling in a Single Microchannel

2008 ◽  
Author(s):  
Jacqueline Barber ◽  
Khellil Sefiane ◽  
David Brutin ◽  
Lounes Tadrist
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Pressure Sensors ◽  
Flow Patterns ◽  
Bubble Nucleation ◽  
Phase Flow ◽  
Vapour Bubble ◽  
Two Phase ◽  
Over Time

Boiling in microchannels remains elusive due to the lack of full understanding of the mechanisms involved. A powerful tool in achieving better comprehension of the mechanisms is detailed imaging and analysis of the two phase flow at a fundamental level. We induced boiling in a single microchannel geometry (hydraulic diameter 727 μm), using a refrigerant FC-72, to investigate several flow patterns. A transparent, metallic, conductive deposit has been developed on the exterior of rectangular microchannels, allowing simultaneous uniform heating and visualisation to be conducted. The data presented in this paper is for a particular case with a uniform heat flux of 4.26 kW/m2 applied to the microchannel and inlet liquid mass flowrate, held constant at 1.33×10−5 kg/s. In conjunction with obtaining high-speed images and videos, sensitive pressure sensors are used to record the pressure drop profiles across the microchannel over time. Bubble nucleation, growth and coalescence, as well as periodic slug flow, are observed in the test section. Phenomena are noted, such as the aspect ratio and Reynolds number of a vapour bubble, which are in turn correlated to the associated pressure drops over time. From analysis of our results, images and video sequences with the corresponding physical data obtained, it is possible to follow visually the nucleation and subsequent both ‘free’ and ‘confined’ growth of a vapour bubble over time.

New Revised Correlation to Predict Pressure Drop for Oil-Gas Two-Phase Flow Through Horizontal Pipe

2007 ◽  
Author(s):  
L. Wenhong ◽  
G. Liejin ◽  
Z. Ximin ◽  
L. Kai ◽  
Y. Long ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Flow Through ◽  
Oil Gas

Visualization of Supercritical Carbon Dioxide Flow Through a Converging-Diverging Nozzle

2019 ◽  
Author(s):  
Chang Hyeon Lim ◽  
Gokul Pathikonda ◽  
Sandeep Pidaparti ◽  
Devesh Ranjan
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Critical Point ◽  
High Speed ◽  
Operating Conditions ◽  
Higher Plant ◽  
Two Phase ◽  
Pressure Profiles ◽  
Flow Through ◽  
Supercritical Carbon

Abstract Supercritical carbon dioxide (sCO2) power cycles have the potential to offer a higher plant efficiency than the traditional Rankine superheated/supercritical steam cycle or Helium Brayton cycles. The most attractive characteristic of sCO2 is that the fluid density is high near the critical point, allowing compressors to consume less power than conventional gas Brayton cycles and maintain a smaller turbomachinery size. Despite these advantages, there still exist unsolved challenges in design and operation of sCO2 compressors near the critical point. Drastic changes in fluid properties near the critical point and the high compressibility of the fluid pose several challenges. Operating a sCO2 compressor near the critical point has potential to produce two phase flow, which can be detrimental to turbomachinery performance. To mimic the expanding regions of compressor blades, flow through a converging-diverging nozzle is investigated. Pressure profiles along the nozzle are recorded and presented for operating conditions near the critical point. Using high speed shadowgraph images, onset and growth of condensation is captured along the nozzle. Pressure profiles were calculated using a one-dimensional homogeneous equilibrium model and compared with experimental data.

scholarly journals Periodic Trends in Two-Phase Flow Through a Vertical Minichannel: Wavelet and Multiscale Entropy Analyses Based on Digital Camera Data

2019 ◽  
Vol 13 (1) ◽  
pp. 51-56
Author(s):  
Grzegorz Górski ◽  
Grzegorz Litak ◽  
Romuald Mosdorf ◽  
Andrzej Rysak
Keyword(s):  
Water Flow ◽  
Two Phase Flow ◽  
Digital Camera ◽  
Flow Patterns ◽  
Multiscale Entropy ◽  
Phase Flow ◽  
Periodic Patterns ◽  
Two Phase ◽  
Periodic Sequences ◽  
Flow Through

Abstract By changing the air and water flow relative rates in the two-phase (air-water) flow through a minichannel, we observe aggregation and partitioning of air bubbles and slugs of different sizes. An air bubble arrangement, which show non-periodic and periodic patterns. The spatiotemporal behaviour was recorded by a digital camera. Multiscale entropy analysis is a method of measuring the time series complexity. The main aim of the paper was testing the possibility of implementation of multiscale entropy for two-phase flow patterns classification. For better understanding, the dynamics of the two-phase flow patterns inside the minichannel histograms and wavelet methods were also used. In particular, we found a clear distinction between bubbles and slugs formations in terms of multiscale entropy. On the other hand, the intermediate region was effected by appearance of both forms in non-periodic and periodic sequences. The preliminary results were confirmed by using histograms and wavelets.

Characteristics of Gas-Liquid Two-Phase Flow Patterns in Miniature Channel Having a Gas Permeable Sidewall

2002 ◽  
Author(s):  
H. Yang ◽  
T. S. Zhao ◽  
P. Cheng
Keyword(s):  
Test Section ◽  
High Speed ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Porous Plate ◽  
Flow Patterns ◽  
Phase Flow ◽  
Two Phase ◽  
Flow Configuration ◽  
Blowing Up

Characteristics of gas-liquid two-phase flow patterns in a miniature square cross-section channel having a gas permeable sidewall have been investigated visually using a high-speed motion analyzer. The problem under consideration is encountered in the design of Direct Feed Methanol Fuel Cells (DMFC). The test section was a horizontally oriented rectangular transparent (Lucite material) channel with its lower wall consisting of a porous plate. Liquid was fed into the test section from its entrance, while gas was injected uniformly into the test section along the lower porous sidewall. The visual study shows the typical flow patterns found in the test section include bubbly flow, plug flow, slug flow, and annular flow. However, unlike the conventional co-current two-phase flow in a channel with gas and liquid uniformly entering from one of its ends, for the flow configuration considered in this work, it was found that two or three of the above mentioned flow patterns appeared simultaneously at different locations of the channel. The length of each flow pattern varied with the flow rates of liquid and gas. A distinct feature of annular flow for the present flow configuration is that small bubbles were continuously generated from the porous plate, which grew by blowing up the liquid film, formed a semi-sphere shape, and then ruptured and released gas into the core flow.

scholarly journals Two-phase flow patterns in adiabatic refrigerant flow through capillary tubes

2020 ◽  
Vol 115 ◽  
pp. 107-116 ◽  
Author(s):  
Luka Lorbek ◽  
Anja Kuhelj ◽  
Matevž Dular ◽  
Andrej Kitanovski
Keyword(s):  
Two Phase Flow ◽  
Flow Patterns ◽  
Phase Flow ◽  
Capillary Tubes ◽  
Two Phase ◽  
Flow Through

scholarly journals Investigating the Characteristics of Two-Phase Flow Using Electrical Capacitance Tomography (ECT) for Three Pipe Orientations

Processes ◽  
2020 ◽  
Vol 8 (1) ◽  
pp. 51 ◽  
Author(s):  
Zeyad Almutairi ◽  
Fayez M. Al-Alweet ◽  
Yusif A. Alghamdi ◽  
Omar A. Almisned ◽  
Othman Y. Alothman
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Electrical Capacitance Tomography ◽  
Experimental Measurements ◽  
Phase Flow ◽  
Electrical Capacitance ◽  
Liquid Holdup ◽  
Two Phase ◽  
Capacitance Tomography

Experiments of gas–liquid flow in a circular pipe for horizontal and inclined positions (upward/downward) are reported. The characteristics of two-phase flow in terms of liquid holdup (ε(L)) and induced flow patterns are studied using three experimental techniques; time-averaged ε(L) from permittivity profiles using electrical capacitance tomography (ECT), instantaneous ε(L) using two fast-closing valves (TFCV), and high-speed camera images (HSCI) to capture/identify the formed flow patterns. Thus, this experimental setup enables the development of more well-defined flow patterns in gas–liquid two-phase flow and allows for multi-technique verification of the results. Taken from experimental measurements, a model is proposed to predict ε(L) for high and low situations. The correlations are a function of the hydrodynamic dimensionless quantities which provide hydrodynamic similarity. Regarding different pipe orientations, ε(L) predictions are comparable to ε(L) from experimental measurements with accepted accuracy: 88% of the predictions are within ±5–15% and 98% are below ±20%. The correlations also were validated by reported results and against correlations available in the literature and show higher prediction accuracy. It is confirmed that the kinematic similarity which is achieved by the gas–liquid velocity ratios and the inertial forces influence the flow pattern and the liquid holdup.

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