scholarly journals Influence of Structural Parameters of Two-throat Nozzle Ejector on Performance of Two-phase Flow Ejector Refrigeration System

2017 ◽  
Vol 105 ◽  
pp. 5091-5097 ◽  
Author(s):  
Kang Huang ◽  
Xianmin Guo ◽  
Peilan Zhang
Keyword(s):  
Two Phase Flow ◽  
Structural Parameters ◽  
Phase Flow ◽  
Refrigeration System ◽  
Two Phase

Research on Two-Phase Flow Instability in Evaporator of Refrigeration System

2010 ◽  
Author(s):  
Nan Liang ◽  
Changqing Tian ◽  
Shuangquan Shao
Keyword(s):  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Density Wave ◽  
Phase Flow ◽  
Constant Mass ◽  
Refrigeration System ◽  
Two Phase

As one kind of fluid machinery related to the two-phase flow, the refrigeration system encounters more problems of instability. It is essential to ensure the stability of the refrigeration systems for the operation and efficiency. This paper presents the experimental investigation on the static and dynamic instability in an evaporator of refrigeration system. The static instability experiments showed that the oscillatory period and swing of the mixture-vapor transition point by observation with a camera through the transparent quartz glass tube at the outlet of the evaporator. The pressure drop versus mass flow rate curves of refrigerant two phase flow in the evaporator were obtained with a negative slope region in addition to two positive slope regions, thus making the flow rate a multi-valued function of the pressure drop. For dynamic instabilities in the evaporation process, three types of oscillations (density wave type, pressure drop type and thermal type) were observed at different mass flow rates and heat fluxes, which can be represented in the pressure drop versus mass flow rate curves. For the dynamic instabilities, density wave oscillations happen when the heat flux is high with the constant mass flow rate. Thermal oscillations happen when the heat flux is correspondingly low with constant mass flow rate. Though the refrigeration system do not have special tank, the accumulator and receiver provide enough compressible volume to induce the pressure drop oscillations. The representation and characteristic of each oscillation type were also analyzed in the paper.

New Experimental Data and Analysis for Two-Phase Flow-Induced Vibration of Tube Bundles: Preliminary Results

2003 ◽  
Author(s):  
Deepanjan Mitra ◽  
Vijay K. Dhir ◽  
Ivan Catton
Keyword(s):  
Two Phase Flow ◽  
Structural Parameters ◽  
Cross Flow ◽  
Instability Criterion ◽  
Phase Flow ◽  
Flow Induced Vibration ◽  
Two Phase ◽  
Void Fractions ◽  
Comparison Of The Results ◽  
Square Array

In the past, fluid-elastic instability in two-phase flow has been largely investigated with air-water flow. In this work, new experiments are conducted in air-water cross-flow with a fully flexible 5 × 3 normal square array having pitch-to-diameter ratio of 1.4. The tubes have a diameter of 0.016 m and a length of 0.21 m. The vibrations are measured using strain gages installed on piano wires used to suspend the tubes. Experiments are carried out for void fractions from 0%–30%. A comparison of the results of the current tests with previous experiments conducted in air-water cross-flow shows that instability occurs earlier in a fully flexible array as compared to a flexible tube surrounded by rigid tubes in an array. An attempt is made to separate out the effects of structural parameters of three different experimental datasets by replotting the instability criterion by incorporating the instability constant K, in the reduced velocity parameter.

The Numerical Simulation and Optimal Design of Nozzle Jet for Gas-Fluid Two Phase Flow

2011 ◽  
Vol 291-294 ◽  
pp. 2403-2406
Author(s):  
Yan Min Li ◽  
Fei Ma
Keyword(s):  
Optimal Design ◽  
Two Phase Flow ◽  
Structural Parameters ◽  
Performance Testing ◽  
Fluid Phase ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Distributions ◽  
And Performance ◽  
The Relationship

Taking a nozzle jet for gas-fluid phase flow as a research object, the influences of the main structural parameters on the vacuum in the internal suction volume are analyzed. Utilizing the software FLUENT to simulate the gas-liquid two-phase flow in nozzle jet with different structural parameters, the pressure distributions are obtained and the relationship between the structural parameters and the vacuum in the suction volume is concerned. The results show that the vacuum in the suction volume of jet reaches the maximum when these structural parameters are some certain values. The research is helpful for the optimal design and performance testing of nozzle jets.

PERMEABILITY MODELS FOR TWO-PHASE FLOW IN FRACTAL POROUS-FRACTURE MEDIA WITH THE TRANSFER OF FLUIDS FROM POROUS MATRIX TO FRACTURE

Fractals ◽  
2021 ◽  
Vol 29 (06) ◽  
pp. 2150148
Author(s):  
TONGJUN MIAO ◽  
AIMIN CHEN ◽  
YAN XU ◽  
SUJUN CHENG ◽  
LIWEI ZHANG ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Two Phase Flow ◽  
Structural Parameters ◽  
Porous Matrix ◽  
Fracture Aperture ◽  
Phase Flow ◽  
Relative Permeabilities ◽  
Two Phase ◽  
Dimension Formula ◽  
Phase Saturation

Study of transport mechanism of two-phase flow through porous-fracture media is of considerable importance to deeply understand geologic behaviors. In this work, to consider the transfer of fluids, the analytical models of dimensionless relative permeabilities for the wetting and non-wetting phases flow are proposed based on the fractal geometry theory for porous media. The proposed models are expressed as functions of micro-structural parameters of the porous matrix and fracture, such as the fractal dimension ([Formula: see text] for pore area, the fractal dimensions [Formula: see text] for wetting phase and for non-wetting phase, porosity ([Formula: see text], the total saturations ([Formula: see text], the porous matrix saturation ([Formula: see text] of the wetting and non-wetting phases, fractal dimension ([Formula: see text] for tortuosity of tortuous capillaries, as well as the ratio ([Formula: see text] of the maximum pore size in porous matrix to fracture aperture. The ratio ([Formula: see text] has a significant impact on the relative permeabilities and total saturations of wetting phases. The results reveal that the flow contribution of wetting phase from the porous matrix to both the seepage behavior of the fracture and total wetting phase saturation can be neglected as [Formula: see text]. The models may shed light on the fundamental mechanisms of the wetting and non-wetting phase flow in porous-fracture media with fluid transfer.

The Structure and Two-Phase Flow Analysis for a New SVLX Static Mixer

2011 ◽  
Vol 130-134 ◽  
pp. 696-700
Author(s):  
Qing Wu ◽  
Nan Li ◽  
Quan Lai Li
Keyword(s):  
Flow Field ◽  
Preliminary Analysis ◽  
Two Phase Flow ◽  
Structural Parameters ◽  
Flow Analysis ◽  
Applied Force ◽  
Phase Flow ◽  
Static Mixer ◽  
Two Phase ◽  
The Cross

A new SVLX static mixer is original designed by the author with the structure of alternative connection of the SV static mixing unit and cross shaped stationary helical fin. The two-phase flow is sheared, separated, impinged and rotated by SV static mixing unit, as well as whirled by the cross shaped stationary helical fin. Hence the mixer efficiency is enhanced. The most advantage of this design is the mixer efficiency is more enhanced with none applied force. Followed by the static mixer structure illustration, the preliminary analysis of the two-phase flow field is carried out, which provides some proofs for the selection and optimization of the new SVLX static mixer structural parameters.

Influence of structural parameters of friction pair on oil temperature rise in hydro-viscous clutch

2019 ◽  
Vol 72 (1) ◽  
pp. 79-85
Author(s):  
Zhibao Li ◽  
Fangwei Xie ◽  
Junyu Sun ◽  
Jie Zhu ◽  
Xudong Zheng ◽  
...  
Keyword(s):  
Temperature Rise ◽  
Two Phase Flow ◽  
Friction Pair ◽  
Structural Parameters ◽  
Outer Radius ◽  
Phase Flow ◽  
Two Phase ◽  
Content Type ◽  
Oil Film ◽  
Inner Radius

Purpose The purpose of this paper is to study the temperature characteristics of hydro-viscous clutch with different structure of friction disks and obtain the distribution of film temperature. Design/methodology/approach The mathematical model of oil film between friction disks with radial grooves is established. Based on the flow rate equation, the temperature rise equation of oil film is deduced. Considering two-phase flow, the temperature distribution in the oil shear stage and the effects of the ratio of inner radius to outer radius on film temperature rise is studied by using computational fluid dynamics (CFD) technology. Findings The results show that when input speed is constant, the increase in the ratio of inner to outer radius leads to an increase in the peak temperature and the decrease in the ratio results in a larger increasing rate of temperature. Originality/value These results are of interest for the study of hydro-viscous drive and its applications. This study can also provide a theoretical basis for the mechanism of temperature rise by considering the effect of two-phase flow.

The Structure and Fluid Flow Analysis for a New DSH Dynamic - Static Combined Mixer

2011 ◽  
Vol 317-319 ◽  
pp. 2122-2125
Author(s):  
Qing Wu ◽  
Nan Li ◽  
Quan Lai Li
Keyword(s):  
Two Phase Flow ◽  
Double Helix ◽  
Structural Parameters ◽  
Flow Analysis ◽  
Dynamic Force ◽  
Phase Flow ◽  
Two Phase ◽  
High Efficient ◽  
Fluid Flow Analysis ◽  
Eddy Flow

A new DSH type dynamic-static combined mixer, which combines the advantages of dynamic mixing agitator and SH type static mixer, with the structure of alternative connection of the turning impeller, liquid shunt unit and double-barreled helical stationary blade, is original designed by the author. The allotype impeller is driven by the two-phase flow and meanwhile the two-phase flow is sheared by the allotype impeller. The double helix eddy flow is formed out of two-phase flow by the stationary blade due to the shearing effect of allotype impeller which results in the improvement of mixture efficiency. The most characteristic of this design is: the mixture is driven by the dynamic force of liquid itself, therefore the energy is saved and the mixture efficiency is enhanced. Followed by the illustration of the structure, the preliminary analysis of the flow field is carried out, which provides some proofs for the selection and optimization of the static-dynamic combined high efficient mixer structural parameters.

ANALYSIS OF FRACTIONAL FLOW FOR TRANSIENT TWO-PHASE FLOW IN FRACTAL POROUS MEDIUM

Fractals ◽  
2016 ◽  
Vol 24 (01) ◽  
pp. 1650013 ◽  
Author(s):  
TING Lu ◽  
YONGGANG DUAN ◽  
QUANTANG FANG ◽  
XIAOLU DAI ◽  
JINSUI WU
Keyword(s):  
Porous Medium ◽  
Fractal Dimension ◽  
Chemical Engineering ◽  
Two Phase Flow ◽  
Structural Parameters ◽  
Phase Flow ◽  
Fractional Flow ◽  
Two Phase ◽  
Fluid Properties ◽  
Fractal Characteristics

Prediction of fractional flow in fractal porous medium is important for reservoir engineering and chemical engineering as well as hydrology. A physical conceptual fractional flow model of transient two-phase flow is developed in fractal porous medium based on the fractal characteristics of pore-size distribution and on the approximation that porous medium consist of a bundle of tortuous capillaries. The analytical expression for fractional flow for wetting phase is presented, and the proposed expression is the function of structural parameters (such as tortuosity fractal dimension, pore fractal dimension, maximum and minimum diameters of capillaries) and fluid properties (such as contact angle, viscosity and interfacial tension) in fractal porous medium. The sensitive parameters that influence fractional flow and its derivative are formulated, and their impacts on fractional flow are discussed.

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