Flow Distribution Characteristics According to Variation of Flow Resistance in the Header Supplying Working Fluid to Multiple Fan Coil Units

2021 ◽  
Vol 33 (8) ◽  
pp. 413-421
Author(s):  
Jinsub Kim ◽  
Ji Hwan Jeong
Keyword(s):  
Flow Resistance ◽  
Flow Distribution ◽  
Working Fluid ◽  
Distribution Characteristics

scholarly journals Inverse Problem for Looped River Networks – Lower oder River Case Study

2013 ◽  
Vol 39 (1) ◽  
pp. 105-118
Author(s):  
Jacek Kurnatowski
Keyword(s):  
Mathematical Modeling ◽  
Flow Resistance ◽  
Flow Distribution ◽  
River Networks ◽  
Sensitivity Equation ◽  
Flow Measurements ◽  
Sensitivity Equation Method ◽  
Coefficients Identification ◽  
Oder River

Abstract Identification of coefficients determining flow resistance, in particular Manning’s roughness coefficients, is one of the possible inverse problems of mathematical modeling of flow distribution in looped river networks. The paper presents the solution of this problem for the lower Oder River network consisting of 78 branches connected by 62 nodes. Using results of six sets of flow measurements at particular network branches it was demonstrated that the application of iterative algorithm for roughness coefficients identification on the basis of the sensitivity-equation method leads to the explicit solution for all network branches, independent from initial values of identified coefficients.

Numerical Investigation of an Asymmetric Double Suction Centrifugal Compressor With Different Backswept Angle Matching for a Wide Operating Range

2017 ◽  
Author(s):  
Hanzhi Zhang ◽  
Dazhong Lao ◽  
Longyu Wei ◽  
Ce Yang ◽  
Mingxu Qi
Keyword(s):  
Mass Flow ◽  
Centrifugal Compressor ◽  
Flow Distribution ◽  
Operating Mode ◽  
Mode Transition ◽  
Distribution Characteristics ◽  
Operating Range ◽  
Stable Operating ◽  
Angle Difference ◽  
Matching Models

The work presented here investigates the characteristics of the different impeller backswept angle matchings for a wide stable operating range in an asymmetric double suction centrifugal compressor. The numerical simulation was employed to investigate the influence of different backswept angle matchings on the stable operating range. The aim is to propose a proper change of the backswept angle matching between two impeller sides to improve the impeller power capability and mass flow distribution, furthermore, to delay the operating mode transition and widen the stable operating range of the compressor. Firstly, the method to determine the optimum backswept angle matching obtained by the theory calculation. Then, three matching models were proposed and analyzed in detail. In three matching models, the backswept angle differences between the front and rear impeller side are 0°, 10° and 20°, respectively. The analysis mainly focused on the influence of the different backswept angle matchings on the compressor flow field characteristics and the mass flow distribution characteristics. The results show that the change of the impeller backswept angle matching can improve the mass flow distribution characteristics for two impeller sides and further reduce the stall mass flow rate of the double suction compressor. The model that the backswept angle difference is 10° can delay the operating mode transition and reduce the stall mass flow of the double suction compressor. The model that the backswept angle difference is 20° can also reduce the stall mass flow and finally enable the front impeller into the stall condition. Therefore, the proper change of the backswept angle matching can achieve the purpose of reducing the stall mass flow and widening the operating range for the double suction centrifugal compressor.

scholarly journals Investigation on Gas-Soot Flow Distribution Characteristic of Soot Capture Process in the Wall-Flow Diesel Particulate Filter

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jianyu Li ◽  
Chunping Lu ◽  
Dongli Tan
Keyword(s):  
Mathematical Model ◽  
Diesel Particulate Filter ◽  
Flow Distribution ◽  
Conservation Equation ◽  
Particulate Filter ◽  
Phase Flow ◽  
Distribution Characteristics ◽  
Two Phase ◽  
Capture Process ◽  
Diesel Particulate

In order to investigate the distribution characteristics of gas-particle two-phase flow in the diesel particulate filter in the capture process, a mathematical model of gas-particle two-phase flow for inside-and-outside filter had been established in the capture process according to the mass conservation equation, momentum conservation equation, and k-ε turbulence equation. The model verification was carried out with the experimental and simulated of flow distribution characteristics of gas-particle two-phase. The obtained results showed that the static pressure gradient along the radial distribution was greater at the inlet of the filter in capture process in the diesel particulate filter, which could easily lead to causing eventual fatigue damage due to stress concentration in the front-end of filter; moreover, the weaker the vortex strength of gas-particle formed in expansion pipe was, the better uniformity of flow velocity and soot concentration distribution were. Therefore, the established mathematical model can be used for predicting gas-particle flow velocity distribution in the diesel particulate filter.

scholarly journals Optimization of thermo-hydraulic characteristics of solar cavity receiver under concentrated heat flux

2019 ◽  
Vol 103 (1) ◽  
pp. 003685041987590
Author(s):  
Yun Hao ◽  
Yueshe Wang
Keyword(s):  
Heat Flux ◽  
Heating Surface ◽  
Flow Distribution ◽  
Working Fluid ◽  
Stable Operation ◽  
Hydraulic Characteristics ◽  
Spot Center ◽  
Research Findings ◽  
High Temperature Steam ◽  
Better Than

It is important to study the effects of heat flux on the thermo-hydraulic characteristics in a solar cavity receiver because of the non-uniform radiation flux temporally and spatially. In this article, we presented a mathematical model of thermo-hydraulic characteristics of a solar cavity receiver, considering the effect of heat flux distribution on the energy transfer (radiation–conduction–convection). Using the model, the thermo-hydraulic characteristics under high concentrated heat flux were studied and then optimized the characteristics from two aspects: tube diameter (22, 27, 32, and 38 mm) and connection structure of the heating surface (H-type, central inlet/outlet, and vertical U-type). It was found that flow distribution changed smoothly at the diameter of 27 mm with the increase of the heat flux; when the diameter of tubes at the certain distance (1.6 σHF) from the spot center was replaced by 38 mm, the thermo-hydraulic characteristics were improved. For the evaporating surfaces, the thermo-hydraulic characteristics of working fluid (water) with the central inlet/outlet connection structure were better than those of the H-type connection structure. For the surperheated surfaces, the vertical U-type connection structure was applied to obtain the high temperature steam. These research findings are helpful for the safe and stable operation of the whole solar power system.

scholarly journals Investigation of flow non-uniformities in the cross-flow heat exchanger with elliptical tubes

2019 ◽  
Vol 108 ◽  
pp. 01009 ◽  
Author(s):  
Stanisław Łopata ◽  
Paweł Ocłoń ◽  
Tomasz Stelmach
Keyword(s):  
Heat Exchanger ◽  
Measurement Data ◽  
Cross Flow ◽  
Flow Distribution ◽  
Transitional Flow ◽  
Working Fluid ◽  
Elliptical Cross ◽  
Flow Heat ◽  
The Cross ◽  
Inflow Conditions

In heat exchangers, especially those with the cross-flow arrangement, it is nearly impossible to achieve the uniform distribution of the working fluid in the tubular space with the currently used inlet and outlet chambers (in some constructions as well). The improper inflow conditions to individual tubes, including those with an elliptical cross-section - often used because of their favorable features compared to round tubes, is the cause of improper heat transfer. In this respect, transitional flow is of particular importance. This flow regime is complex and challenging to model. Therefore, it is necessary to perform experimental verification. For this purpose, an appropriate stand was built, allowing to investigate the flow of the working fluid (water) to the elliptical tubes in the cross-current heat exchanger. The paper presents the results of measurements for manifold geometry, which are currently used in practice (for heat exchanger constructions). The analysis of the measurement data confirms the nonuniform flow distribution to individual tubes of the heat exchanger.

Deposition of aerosol particles and flow resistance in mathematical and experimental airway models

1983 ◽  
Vol 55 (1) ◽  
pp. 154-163 ◽  
Author(s):  
C. S. Kim ◽  
L. K. Brown ◽  
G. G. Lewars ◽  
M. A. Sackner
Keyword(s):  
Flow Resistance ◽  
Airway Resistance ◽  
Flow Distribution ◽  
Aerosol Deposition ◽  
Lung Model ◽  
Straight Tube ◽  
Small Airways ◽  
Two Phase ◽  
Gas Liquid Flow ◽  
Airway Walls

Aerosol deposition and flow resistance in obstructed airways were determined from five mathematical and experimental airway models. The first three models were theoretical and based upon Weibel's symmetrical lung model with 1) uniform reduction of airway diameter in various groups of airway generations; 2) obstruction of a few major airways such that a severe uneven flow distribution occurs in the lung; 3) focal constriction of selected large airways. In model 3, an empirical formula was utilized to assess deposition and resistance in the constricted airways. The remaining two models were tested experimentally; 4) oscillation of a compliant wall in a straight tube and 5) two-phase gas-liquid flow utilizing human sputum in a rigid branching tube. In models 1, 2, and 3, airway resistance increased to a greater extent than did the increase of aerosol deposition except when small airways were obstructed in model 1. Here, the increase of aerosol deposition was slightly higher than the rise in airway resistance. A sharp increase of aerosol deposition with a minimal increase of flow resistance was demonstrated in models 4 and 5. These data indicate that aerosol deposition may be a more sensitive indicator of airway abnormalities than overall airway resistance in small airways obstruction, during oscillation of large and medium airway walls, and when excessive secretions within the airways move with a wave or slug motion.

Simulate Design of Direct Air Cooling Exhausted Duct System for 1000MW Super-Critical Thermal Power Unit

2014 ◽  
Vol 535 ◽  
pp. 180-184
Author(s):  
Chun Qing Wang ◽  
Cai Xia Bian ◽  
Di Wang
Keyword(s):  
Pressure Drop ◽  
Flow Field ◽  
Power Unit ◽  
Flow Resistance ◽  
Thermal Power ◽  
Flow Distribution ◽  
Cooling Power ◽  
Air Cooling ◽  
Exhaust Pipe ◽  
Balanced Flow

Balancing flow distribution and decreasing the pressure drop in each vapor distributing pipe are the importance of the study of exhaust pipe of direct air cooling power unit.In order to balance flow distribution and decreasing the pressure drop in each vapor distributing pipe,and simulate the flow field when add different chamfer on the back of exhausted pipe or not ,then using the CFD software called FLUENT,the steam flow field of exhausted pipe for a 1000 MW power unit with direct air cooling is stimulated under typical steam turbine conditions.The result shows that the steam flows through each distribution pipe with balanced flow under the condition of chamfer angle of 30 °and the flow resistance is much lower than before．

Flow Distribution Characteristics and Control in Marine Gas Turbine Diffusers

1984 ◽  
Vol 106 (3) ◽  
pp. 654-660
Author(s):  
M. K. Ellingsworth ◽  
Ho-Tien Shu ◽  
S. C. Kuo
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Waste Heat Recovery ◽  
Waste Heat ◽  
Flow Distribution ◽  
Distribution Characteristics ◽  
Nonuniform Flow ◽  
Technical Problems ◽  
And Control

The object of this study was to investigate flow distribution characteristics and control in the marine gas turbine diffusers most suitable for waste heat recovery systems. The major technical problems associated with nonuniform flow distributions in heat-exchanger or flow-equipment systems were reviewed. Various means to alleviate or minimize these undesirable problems were evaluated. Four sets of candidate flow-distribution data were selected from the measured exhaust velocities of typical marine gas turbines for input to the present study. A two-dimensional turbulent flow model for diffusers was developed and computerized, and five diffuser geometries suitable for marine gas turbine waste-heat recovery applications were investigated, based on the actual inlet velocity data. The exit flow distribution characteristics (velocity, mass-flux, pressure recovery, and temperature) and diffuser performance with and without flow-distribution controls were analyzed using the computer programs developed. It was found that nonuniform flow distribution in the gas turbine exhaust can reduce diffuser efficiency to half of that attainable with uniform flow, and that the diffuser exhaust velocities will be more uniform by using guide vanes and/or flow injection than merely using nonsymmetric diffusion angles. The diffuser efficiency can be improved 20 to 36 percentage points by using these contort means.

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