scholarly journals Experimental Data of Supercritical Carbon Dioxide (sCO2) Compressor At Various Fluid States

2021 ◽  
Author(s):  
Alexander J. Hacks ◽  
Ihab Abd El Hussein ◽  
Haikun Ren ◽  
Sebastian Schuster ◽  
Dieter Brillert
Keyword(s):  
Experimental Data ◽  
Pressure Ratio ◽  
Phase Region ◽  
Experimental Results ◽  
Data Repository ◽  
Design Tools ◽  
Two Phase ◽  
Analysis And Design ◽  
Cad Models ◽  
Inlet Conditions

Abstract This paper presents experimental data on a centrifugal compressor operated with CO2. Temperature and pressure at the inlet of the compressor are varied to cover the supercritical region from the liquid-like to the gas-like region. In addition, inlet conditions in the two-phase region are also included. Thus, the experimental test campaign considers thermodynamic conditions relevant for the future energy conversion with sCO2-Joule cycles. Experimental results are presented as compressor pressure ratio vs inlet mass flow rate at different rotational speeds and throttle positions. Reliable conclusions can be drawn from the experimental results since the reproducibility of the measurements has been demonstrated by conducting experiments in two different test rigs, and measurement uncertainties are reported. The entire compressor geometry is disclosed in a data repository, including CAD models, and input files suitable for mean-line and grid generation programs. Thus, the experimental results are exploitable by the scientific community and pave the road for validated analysis and design tools in the context of the sCO2-Joule cycle. The presented results open the possibility to estimate uncertainties of analysis and design tools with little effort since geometry information can be quickly integrated. The experimental data is already used in this paper to obtain the accuracy of a CFD code and a mean-line program for sCO2. In addition to quantifying uncertainties, the results presented can be used to identify shortcomings of existing tools. This can be an essential step in the exploration of the sCO2-Joule cycle.

The Critical and Two-Phase Flow of Steam

1961 ◽  
Vol 83 (2) ◽  
pp. 145-154 ◽  
Author(s):  
William G. Steltz
Keyword(s):  
Digital Computer ◽  
Critical Pressure ◽  
Single Phase ◽  
Unit Area ◽  
Pressure Ratio ◽  
Phase Region ◽  
Critical Flow ◽  
Two Phase ◽  
Analytic Expressions ◽  
Inlet Conditions

The results of a digital computer and analytic study of the critical flow of a compressible fluid are presented in this paper. The expanding flow of a fluid in a single-phase region as well as the expansion of a fluid to a two-phase region is considered and described by analytic expressions relating choking velocity, critical pressure ratio, and flow per unit area characteristics. A comparison is made of the analytic results which assume a constant value of the isentropic expansion exponent, with the digital computer results using the actual properties of steam. All analyses assume the fluid to be in thermodynamic equilibrium. A skeleton Mollier diagram is presented for steam showing the exponent in the wet and superheated regions. The choking velocity is presented in plot form as a function of the inlet conditions as well as state point conditions; critical pressure ratio is presented as a function of inlet conditions. The critical flow per unit area is presented in the form of a factor K plotted versus inlet conditions; this factor K when multiplied by inlet pressure produces the desired value of critical flow.

Validating Numerical CFD Simulations With Experimental Data for Turbulence Phenomena in Axial Flow Gas Turbine Diffusers

2009 ◽  
Author(s):  
Farrokh Zarifi-Rad ◽  
Hamid Vajihollahi ◽  
James O’Brien
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Axial Flow ◽  
Experimental Results ◽  
Scale Model ◽  
Data Set ◽  
Pressure Profiles ◽  
Scale Models ◽  
Inlet Conditions

Scale models give engineers an excellent understanding of the aerodynamic behavior behind their design; nevertheless, scale models are time consuming and expensive. Therefore computer simulations such as Computational Fluid Dynamics (CFD) are an excellent alternative to scale models. One must ask the question, how close are the CFD results to the actual fluid behavior of the scale model? In order to answer this question the engineering team investigated the performance of a large industrial Gas Turbine (GT) exhaust diffuser scale model with performance predicted by commercially available CFD software. The experimental results were obtained from a 1:12 scale model of a GT exhaust diffuser with a fixed row of blades to simulate the swirl generated by the last row of turbine blades five blade configurations. This work is to validate the effect of the turbulent inlet conditions on an axial diffuser, both on the experimental front and on the numerical analysis approach. The object of this work is to bring forward a better understanding of velocity and static pressure profiles along the gas turbine diffusers and to provide an accurate experimental data set to validate the CFD prediction. For the CFD aspect, ANSYS CFX software was chosen as the solver. Two different types of mesh (hexagonal and tetrahedral) will be compared to the experimental results. It is understood that hexagonal (HEX) meshes are more time consuming and more computationally demanding, they are less prone to mesh sensitivity and have the tendancy to converge at a faster rate than the tetrahedral (TET) mesh. It was found that the HEX mesh was able to generate more consistent results and had less error than TET mesh.

Analysis of two-phase ejectors with Fabri choking

2002 ◽  
Vol 216 (5) ◽  
pp. 607-621 ◽  
Author(s):  
W E Lear ◽  
G M Parker ◽  
S A Sherif
Keyword(s):  
Single Phase ◽  
Phase Region ◽  
Working Fluid ◽  
Two Phase ◽  
Cross Sectional ◽  
Flow Phenomena ◽  
Mass Flowrate ◽  
Inlet Conditions ◽  
R 134A ◽  
Phase Fluid

A one-dimensional mathematical model was developed using the equations governing the flow and thermodynamics within a jet pump with a mixing region of constant cross-sectional area. The analysis is capable of handling two-phase flows and the resulting flow phenomena such as condensation shocks and the Fabri limit on the secondary mass flowrate. This work presents a technique for quickly achieving first-approximation solutions for two-phase ejectors. The thermodynamic state of the working fluid, R-134a for this analysis, is determined at key locations within the ejector. From these results, performance parameters are calculated and presented for varying inlet conditions. The Fabri limit was found to limit the operational regime of the two-phase ejector because, in the two-phase region, the speed of sound may be orders of magnitude smaller than in a single-phase fluid.

The Effect of the Treatment of Localised Friction in Two-Phase Mixtures on the Stability of Parallel Channels

2002 ◽  
Author(s):  
H. N. Abdou ◽  
V. B. Garea ◽  
A. E. Larreteguy
Keyword(s):  
Homogeneous Model ◽  
Stability Boundary ◽  
Density Wave ◽  
Phase Region ◽  
Experimental Results ◽  
Exact Equation ◽  
Two Phase ◽  
Heated Channel ◽  
Phase Mixture ◽  
The Stability

A one-dimensional analytical model has been developed to be used for the linear analysis of density-wave oscillations in a parallel heated channel. The heated channel is divided into a single-phase and a two-phase region. The two-phase region is represented by the homogeneous model. The localised friction at the channel exit is treated considering the two-phase mixture. The exact equation for the total channel pressure drop is perturbed around the steady state. The stability characteristics of the heated channel are investigated using the Nyquist criterion. The marginal stability boundary (MSB) is determined in the two-dimensional thermodynamic equilibrium space parameters, the subcooled boiling number and the phase change number. The predictions of the model are compared with experimental results published in open literature. The results indicate a more stable system with (1) low system pressure, (2) high inlet restriction, (3) low outlet restriction, and (4) high inlet velocity. The results show that the model agrees well with the available experimental data. In particular, the results show the significance of correcting the localised friction due to the presence of the two-phase mixture in the two-phase region: explicit inclusion of the two-phase localised friction improves the agreement with experimental results. This effect is more important for high heating power and high inlet subcooling.

Two-Phase Flow-Induced Forces on Bends in Small Scale Tubes

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
M. F. Cargnelutti ◽  
S. P. C. Belfroid ◽  
W. Schiferli
Keyword(s):  
Experimental Data ◽  
Structural Integrity ◽  
Two Phase Flow ◽  
Experimental Results ◽  
Small Scale ◽  
Phase Flow ◽  
Momentum Exchange ◽  
Two Phase ◽  
Worst Case ◽  
Good Agreement

Two-phase flow occurs in many situations in industry. Under certain circumstances, it can be a source of flow-induced vibrations. The forces generated can be sufficiently large to affect the performance or efficiency of an industrial device. In the worst-case scenario, the mechanical forces that arise may endanger structural integrity. Thus, it is important to take these forces into account in designing industrial machinery to avoid problems during operation. Although the occurrence of such forces is well known, not much is known about their magnitudes because, unfortunately, the amount of experimental data available in literature are rather limited. This paper describes the experiments performed to measure forces in 6 mm diameter tubing containing a bend. Experiments are performed on bends of different radii, with the bend positioned horizontally or vertically. The experimental results are analyzed based on flow regime and bend configuration. A comparison with available experimental results for bigger internal pipe diameter shows a general good agreement. To improve future predictions, a simple model based on momentum exchange is proposed to estimate the forces generated by multiphase flow. The proposed model shows a good agreement with the experimental data.

A Model for Cw Laser Recrystallization Including Reflectivity Effects

1983 ◽  
Vol 23 ◽  
Author(s):  
I.D. Calder
Keyword(s):  
Excellent Agreement ◽  
Solid Phase ◽  
Phase Region ◽  
Experimental Results ◽  
Two Phase ◽  
Cw Laser ◽  
Laser Recrystallization ◽  
Outer Annulus ◽  
Analytic Expressions ◽  
Practical Model

ABSTRACTA simple, practical model is developed for cw laser recrystallization of silicon and SOI structures, taking into account spatial variations in optical reflectivity. The power absorption is assumed to be uniform within each of three regions: the central molten spot, the annular two-phase region, and an outer annulus to account for absorption in the solid phase. Analytic expressions are obtained for the radial and depth dependence of the temperature, for the melt depth, the melt radius, the melt threshold, the crystallization threshold and the substrate melt threshold. SOI structures are considered and comparison with some experimental results shows excellent agreement.

scholarly journals Modification of the Redlich-Kwong-Aungier Equation of State to Determine the Degree of Dryness in the CO2 Two-phase Region

2021 ◽  
Vol 24 (4) ◽  
pp. 17-27
Author(s):  
Hanna S. Vorobieva ◽  
Keyword(s):  
Experimental Data ◽  
Equation Of State ◽  
Gas Phase ◽  
Saturated Vapor ◽  
Phase Region ◽  
Working Fluid ◽  
Two Phase ◽  
Real Gas ◽  
Liquid Phases ◽  
Good Agreement

The degree of dryness is the most important parameter that determines the state of a real gas and the thermodynamic properties of the working fluid in a two-phase region. This article presents a modified Redlich-Kwong-Aungier equation of state to determine the degree of dryness in the two-phase region of a real gas. Selected as the working fluid under study was CO2. The results were validated using the Span-Wanger equation presented in the mini-REFPROP program, the equation being closest to the experimental data in the CO2 two-phase region. For the proposed method, the initial data are temperature and density, critical properties of the working fluid, its eccentricity coefficient, and molar mass. In the process of its solution, determined are the pressure, which for a two-phase region becomes the pressure of saturated vapor, the volumes of the gas and liquid phases of a two-phase region, the densities of the gas and liquid phases, and the degree of dryness. The saturated vapor pressure was found using the Lee-Kesler and Pitzer method, the results being in good agreement with the experimental data. The volume of the gas phase of a two-phase region is determined by the modified Redlich-Kwong-Aungier equation of state. The paper proposes a correlation equation for the scale correction used in the Redlich-Kwongda-Aungier equation of state for the gas phase of a two-phase region. The volume of the liquid phase was found by the Yamada-Gann method. The volumes of both phases were validated against the basic data, and are in good agreement. The results obtained for the degree of dryness also showed good agreement with the basic values, which ensures the applicability of the proposed method in the entire two-phase region, limited by the temperature range from 220 to 300 K. The results also open up the possibility to develop the method in the triple point region (216.59K-220 K) and in the near-critical region (300 K-304.13 K), as well as to determine, with greater accuracy, the basic CO2 thermodynamic parameters in the two-phase region, such as enthalpy, entropy, viscosity, compressibility coefficient, specific heat capacity and thermal conductivity coefficient for the gas and liquid phases. Due to the simplicity of the form of the equation of state and a small number of empirical coefficients, the obtained technique can be used for practical problems of computational fluid dynamics without spending a lot of computation time.

NUMERICAL AND EXPERIMENTAL INVESTIGATION OF THE FLOW CHARACTERISTICS OF R134a FLOWING THROUGH ADIABATIC HELICAL CAPILLARY TUBES

2012 ◽  
Vol 20 (04) ◽  
pp. 1250019 ◽  
Author(s):  
SUKKARIN CHINGULPITAK ◽  
JATUPORN KAEW-ON ◽  
SOMCHAI WONGWISES
Keyword(s):  
Experimental Data ◽  
Capillary Tube ◽  
Flow Characteristics ◽  
Phase Region ◽  
Liquid Region ◽  
Alternative Refrigerants ◽  
Capillary Tubes ◽  
Local Pressure ◽  
Two Phase ◽  
Comparison Results

This paper presents numerical and experimental results of the flow characteristics of R134a flowing through adiabatic helical capillary tubes. The local pressure distribution along the length of the capillary tubes is measured at inlet pressures ranging from 10 to 14 bar, mass flow rates from 8 to 20 kg h-1, and degrees of subcooling from 0.5°C to 15°C. The theoretical model is based on conservation of mass, energy and the momentum of the fluids in the capillary tube. The model is divided into three regions: subcooled liquid region, metastable liquid region and equilibrium two-phase region and can be applied for various tube geometries, new alternative refrigerants and critical or noncritical flow conditions. The model is validated by comparing results from the present experimental data with that of the available literature. Based on the comparison results, the model used in the present study provides reasonable agreement with the experimental data.

A Generalized Neural Network Model of Refrigerant Mass Flow Through Adiabatic Capillary Tubes and Short Tube Orifices

2007 ◽  
Vol 129 (12) ◽  
pp. 1559-1564 ◽  
Author(s):  
Ling-Xiao Zhao ◽  
Chun-Lu Zhang ◽  
Liang-Liang Shao ◽  
Liang Yang
Keyword(s):  
Neural Network ◽  
Experimental Data ◽  
Mass Flow ◽  
Transfer Functions ◽  
Heat Pumps ◽  
Capillary Tubes ◽  
Two Phase ◽  
Bp Network ◽  
Inlet Conditions ◽  
Short Tube

Adiabatic capillary tubes and short tube orifices are widely used as expansive devices in refrigeration, residential air conditioners, and heat pumps. In this paper, a generalized neural network has been developed to predict the mass flow rate through adiabatic capillary tubes and short tube orifices. The input/output parameters of the neural network are dimensionless and derived from the homogeneous equilibrium flow model. Three-layer backpropagation (BP) neural network is selected as a universal function approximator. Log sigmoid and pure linear transfer functions are used in the hidden layer and the output layer, respectively. The experimental data of R12, R22, R134a, R404A, R407C, R410A, and R600a from the open literature covering capillary and short tube geometries, subcooled and two-phase inlet conditions, are collected for the BP network training and testing. Compared with experimental data, the overall average and standard deviations of the proposed neural network are 0.75% and 8.27% of the measured mass flow rates, respectively.

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.

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