GAS-LIQUID FLOW DISTRIBUTION UNIFORMITY PARAMETERS IN UPWARD MULTI-PASS COMPACT EVAPORATOR

2016 ◽  
Vol 78 (10-3) ◽  
Author(s):  
Zuradzman Mohamad Razlan ◽  
Hazry Desa ◽  
Shahriman Abu Bakar ◽  
Khairunizam Wan ◽  
Ishak Ibrahim ◽  
...  
Keyword(s):  
Liquid Flow ◽  
Water Distribution ◽  
Flow Distribution ◽  
Stratified Flow ◽  
Air Conditioner ◽  
Air Velocity ◽  
Inlet Condition ◽  
Automobile Air Conditioner ◽  
Distribution Uniformity ◽  
Gas Liquid Flow

The gas-liquid flow distributions in multi-pass upward parallel channels that simulate the evaporator for the automobile air-conditioner system were examined experimentally. In this paper, the attentions are (1) To study the influences of the backpressure condition at the branch outlets and of the flow-inlet condition at the header entrance on the gas-liquid distributions to the branches, (2) To discover the most influenced parameter to the flow distribution uniformity by using design of experiment method. Experiments were conducted in an isothermal air-water flow system. The influence of the backpressure condition on the flow distributions changed depending on the flow-inlet condition. In the stratified-flow inlet, the backpressure condition was highly influential in both the air and water distributions, and the uniform water distribution that was ideal for the evaporators could not be achieved even if air was distributed uniformly to all branches. In the mist-flow inlet, the water distribution was insensitive to the backpressure conditions and its uniformity was improved in comparison with that in the stratified-flow inlet. The flow distribution uniformity for gas phase is influenced mostly by superficial air velocity, and the flow distribution uniformity of liquid phase is mostly influence by 2-way interaction of parameters which are flow pattern and superficial air velocity.

Gas-Liquid Distributions in Upward Multi-Pass Channels of Compact Evaporator

2010 ◽  
Author(s):  
Zuradzman Mohamad Razlan ◽  
Ryota Isobe ◽  
Yasuhiro Mizuno ◽  
Hiroaki Goshima ◽  
Masafumi Hirota ◽  
...  
Keyword(s):  
Air Conditioning ◽  
Water Distribution ◽  
Flow System ◽  
Stratified Flow ◽  
Air Conditioning System ◽  
Inlet Condition ◽  
Mist Flow ◽  
Automobile Air Conditioning System ◽  
Parallel Channels ◽  
Gas Liquid Flow

The gas-liquid flow distributions in multi-pass upward parallel channels that simulate the evaporator for the automobile air-conditioning system were examined experimentally. Attention was directed to the influences of the backpressure condition at the branch outlets and of the flow-inlet condition at the header entrance on the gas-liquid distributions to the branches. Experiments were conducted in an isothermal air-water flow system. The influence of the backpressure condition on the flow distributions changed depending on the flow-inlet condition. In the stratified-flow inlet, the backpressure condition was highly influential in both the air and water distributions, and the uniform water distribution that was ideal for the evaporators could not be achieved even if air was distributed uniformly to all branches. In the mist-flow inlet, the water distribution was insensitive to the backpressure conditions and its uniformity was improved in comparison with that in the stratified-flow inlet.

Modeling the Onset of Gas Entrainment in a Reduced T-Junction With Co-Current Stratified Gas-Liquid Flow

2012 ◽  
Vol 134 (8) ◽  
Author(s):  
Robert C. Bowden ◽  
Ibrahim G. Hassan
Keyword(s):  
Liquid Flow ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Critical Height ◽  
Cross Sectional ◽  
Gas Entrainment ◽  
Mass Fluxes ◽  
Height Prediction ◽  
Dip Angle ◽  
Gas Liquid Flow

A model was developed to predict the onset of gas entrainment in a single downward oriented branch. The branch was installed on a horizontal square cross-sectional channel having a smooth stratified co-currently flowing gas-liquid regime in the inlet region. The branch flow was simulated as a three-dimensional point-sink while the run flow was treated as a uniform velocity at the critical dip. Experiments were performed to determine the critical liquid flow distribution between the run and the branch. A correlation was developed relating the branch Froude number to the ratio of the superficial liquid mass fluxes in the run and the branch. The correlation was used as a boundary condition in the model. A methodology was developed using digital imaging to record the coordinates of the critical dip at the onset of as entrainment. The dip angle was found to range between 40 to 60 degrees and constant dip angles of 40, 50 and 60 degrees were selected as boundary conditions. The critical height was predicted to within 50% of experiments with the error attributed to differences in the modeled and experimental geometries. A semi-empirical analysis using the experimental geometry yielded a critical height prediction to within 20% of experimental results.

GAS–LIQUID FLOW SIMULATION IN REFRIGERANT DISTRIBUTOR FOR AIR CONDITIONER

2013 ◽  
Vol 21 (03) ◽  
pp. 1350017 ◽  
Author(s):  
EIJI ISHII ◽  
KAZUKI YOSHIMURA
Keyword(s):  
Liquid Film ◽  
Liquid Flow ◽  
Hybrid Method ◽  
Distribution Ratio ◽  
Small Diameter ◽  
Flow Simulation ◽  
Grid Method ◽  
Air Conditioner ◽  
Bend Pipe ◽  
Gas Liquid Flow

Heat exchangers with small-diameter multi-path tubes have been recently used to improve the efficiency of air conditioners. The difficulty in using tubes with small diameters and multi-paths is the nonuniformity of refrigerant distribution in refrigerant distributors, which results in lower heat-exchange efficiency. Grid methods, such as the volume of fluid method, are now widely used to simulate detailed motions of gas–liquid interfaces. A weak point of grid methods is the numerical diffusion of interfaces that occurs if the scale of interfaces becomes close to the computational grid sizes. We previously developed a particle/grid hybrid method for simulating multi-scale free surfaces. For this study, we modified the hybrid method and applied it to gas–liquid flow simulations in a distributor. The liquid film behaviors in both the distributor and a bend pipe placed in the upstream of the distributor were simulated mainly using the particle method, and gas flows were simulated using the grid method. The predicted liquid film near the outer circumference of the curvature in the bend pipe was thicker than that of near inner circumference of the curvature, which qualitatively agreed with the measurement. The simulated distribution ratio under a steady-flow condition agreed well with the measurement; the predicted distribution ratio was 0.63 and the measured distribution ratio was 0.6.

Study on Gas-Liquid Two-Phase Flow Distribution Inside a Flute Header

2020 ◽  
Author(s):  
Liping Pang ◽  
Shangmin Li ◽  
Hu Yuan ◽  
Liqiang Duan
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Liquid Flow ◽  
Two Phase Flow ◽  
Phase Distribution ◽  
Flow Distribution ◽  
Phase Flow ◽  
Two Phase ◽  
Parallel Channels ◽  
Gas Liquid Flow

Abstract When the supercritical boiler is working at low load during flexible operation, the uneven distribution of the gas-liquid flow at the intermediate header may affect the safety of the water-cooled wall at the vertical parallel panels. In order to improve the uniformity of gas-liquid flow distribution in the water-cooled wall of intermediate header and study the internal flow mechanism, a flute inside the header is applied with parallel vertical parallel channels and experiments under different operating conditions are conducted to verify the effectiveness of this geometrical structure. The flow pattern in the experiment belongs to stratified and wavy flow. Computational fluid dynamic (CFD) simulation is conducted in order to investigate two-phase flow distribution behavior inside a flute header. It was found that the radial gas phase distribution in the flute tube shows a symmetrical relationship, and there are two vortexes in opposite directions. With the increasing distance from the inlet, the uniformity of the gas phase distribution becomes even. The gravity is greater than the drag force, which has effect on the two-phase flow distribution. The gas phase velocity has been improved inside flute section and liquid phase flow has more even flow distribution along annular section. It makes liquid phase sent to far end of flute header. That benefits two-phase flow distribution along 10 parallel channels equally.

SPLITTING CHARACTERISTICS AND FLOW DISTRIBUTION OF GAS-LIQUID FLOW IN TWO PARALLEL PIPES

2010 ◽  
Vol 22 (3) ◽  
pp. 247-266
Author(s):  
Yehuda Taitel ◽  
Bella Gurevich ◽  
Dvora Barnea
Keyword(s):  
Liquid Flow ◽  
Flow Distribution ◽  
Gas Liquid Flow
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