Predictions of Two-Phase Critical Flow Boundary and Mass Flow Rate Across Chokes

2007 ◽  
Author(s):  
Eissa M. Alsafran ◽  
Mohan Gajanan Kelkar
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Critical Flow ◽  
Two Phase ◽  
Flow Boundary

Predictions of Two-Phase Critical-Flow Boundary and Mass-Flow Rate Across Chokes

2009 ◽  
Vol 24 (02) ◽  
pp. 249-256 ◽  
Author(s):  
Eissa M. Alsafran ◽  
Mohan G. Kelkar
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Critical Flow ◽  
Two Phase ◽  
Flow Boundary

Metering of Steam-Water Two-Phase Flow by Sharp-Edged Orifices

1965 ◽  
Vol 180 (1) ◽  
pp. 549-572 ◽  
Author(s):  
Russell James
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Critical Flow ◽  
Water Mixture ◽  
Two Phase ◽  
In Series ◽  
Trial And Error Method ◽  
Error Method ◽  
Stagnation Enthalpy

This paper describes work conducted on the passage of steam-water mixtures through standard sharp-edged orifices for the prediction of flow conditions. When the stagnation enthalpy or alternatively the dryness fraction at the orifice is known, it is shown that the mass flow rate can be approximately determined. For the case where a steam-water mixture passes through a pipeline to the atmosphere or to a low-pressure receiver so that critical flow occurs at the outlet, both the mass flow rate and the stagnation enthalpy may be approximately evaluated using an orifice meter in series with a pressure tapping located at the point of critical flow. In this case, a trial-and-error method is necessary. The experimental results were within a range of dryness fractions from 1 per cent to 56 per cent, orifice pressures from 75 to 275 lb/in2 abs., differentials from 15 to 780 mmHg under water and flow rates from 54 700 to 508 000 lb/h. Orifices of 5.591 and 6.615 in diameter were installed in 7.9-in diameter pipes which were equipped with radius ( D and D/2) taps. The method employs a correlation between the homogeneous dryness fraction x, and a corrected dryness fraction x m necessary for evaluating the two-phase density used in the conventional single-phase meter equation.

Thermal Characterization of Interlayer Microfluidic Cooling of Three-Dimensional Integrated Circuits With Nonuniform Heat Flux

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Yoon Jo Kim ◽  
Yogendra K. Joshi ◽  
Andrei G. Fedorov ◽  
Young-Joon Lee ◽  
Sung-Kyu Lim
Keyword(s):  
Integrated Circuits ◽  
Mass Flow Rate ◽  
Thermal Management ◽  
Mass Flow ◽  
Flow Rate ◽  
Single Phase ◽  
Hot Spot ◽  
Three Dimensional ◽  
Two Phase ◽  
Two Phase Cooling

It is now widely recognized that the three-dimensional (3D) system integration is a key enabling technology to achieve the performance needs of future microprocessor integrated circuits (ICs). To provide modular thermal management in 3D-stacked ICs, the interlayer microfluidic cooling scheme is adopted and analyzed in this study focusing on a single cooling layer performance. The effects of cooling mode (single-phase versus phase-change) and stack/layer geometry on thermal management performance are quantitatively analyzed, and implications on the through-silicon-via scaling and electrical interconnect congestion are discussed. Also, the thermal and hydraulic performance of several two-phase refrigerants is discussed in comparison with single-phase cooling. The results show that the large internal pressure and the pumping pressure drop are significant limiting factors, along with significant mass flow rate maldistribution due to the presence of hot-spots. Nevertheless, two-phase cooling using R123 and R245ca refrigerants yields superior performance to single-phase cooling for the hot-spot fluxes approaching ∼300 W/cm2. In general, a hybrid cooling scheme with a dedicated approach to the hot-spot thermal management should greatly improve the two-phase cooling system performance and reliability by enabling a cooling-load-matched thermal design and by suppressing the mass flow rate maldistribution within the cooling layer.

scholarly journals Development of Hybrid Airlift-Jet Pump with Its Performance Analysis

2018 ◽  
Vol 8 (9) ◽  
pp. 1413 ◽  
Author(s):  
Dan Yao ◽  
Kwongi Lee ◽  
Minho Ha ◽  
Cheolung Cheong ◽  
Inhiug Lee
Keyword(s):  
Boundary Conditions ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Stokes Equations ◽  
Flow Characteristics ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Jet Pump ◽  
Two Phase

A new pump, called the hybrid airlift-jet pump, is developed by reinforcing the advantages and minimizing the demerits of airlift and jet pumps. First, a basic design of the hybrid airlift-jet pump is schematically presented. Subsequently, its performance characteristics are numerically investigated by varying the operating conditions of the airlift and jet parts in the hybrid pump. The compressible unsteady Reynolds-averaged Navier-Stokes equations, combined with the homogeneous mixture model for multiphase flow, are used as the governing equations for the two-phase flow in the hybrid pump. The pressure-based methods combined with the Pressure-Implicit with Splitting of Operators (PISO) algorithm are used as the computational fluid dynamics techniques. The validity of the present numerical methods is confirmed by comparing the predicted mass flow rate with the measured ones. In total, 18 simulation cases that are designed to represent the various operating conditions of the hybrid pump are investigated: eight of these cases belong to the operating conditions of only the jet part with different air and water inlet boundary conditions, and the remaining ten cases belong to the operating conditions of both the airlift and jet parts with different air and water inlet boundary conditions. The mass flow rate and the efficiency are compared for each case. For further investigation into the detailed flow characteristics, the pressure and velocity distributions of the mixture in a primary pipe are compared. Furthermore, a periodic fluctuation of the water flow in the mass flow rate is found and analyzed. Our results show that the performance of the jet or airlift pump can be enhanced by combining the operating principles of two pumps into the hybrid airlift-jet pump, newly proposed in the present study.

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.

Predicted performance of a two-phase underwater ramjet with a Laval nozzle

2018 ◽  
Vol 233 (3) ◽  
pp. 937-948
Author(s):  
Jiarui Zhang ◽  
Zhixun Xia ◽  
Liya Huang ◽  
Likun Ma
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Laval Nozzle ◽  
Fluid Model ◽  
Bubbly Flow ◽  
Engine Performance ◽  
Orifice Diameter ◽  
Two Phase ◽  
Convergent Nozzle

To predict engine performance and further instruct the integral engine design, a more reasonable and accurate numerical model of the two-phase underwater ramjet was introduced in this article by considering the bubble formation process. Two-fluid model was used to examine the bubbly flow in the nozzle and its mathematical model was solved by a fourth-order Runge–Kutta method. Subsequently, the influences of vessel velocity, gas mass flow rate, navigational depth, and orifice diameter of the bubble injector on the performance of the engine were discussed. Results show that, compared with convergent nozzle, Laval nozzle is proved to improve the thrust of the engine, especially at relatively high velocity and gas mass flow rate. With the other conditions fixed, there is an optimum vessel velocity for the ramjet, in which maximum thrust is generated. And a smaller orifice diameter always promotes the engine performance, while this promotion is negligible when the orifice diameter is smaller than 1 mm. Besides, increasing backpressure will cause serious performance drop, which means that the the two-phase underwater ramjet is only efficient for shallow depths.

A vibration probe sensor for mass flow rate measurement of gas-solid two-phase flow

Sensor Review ◽  
2016 ◽  
Vol 36 (2) ◽  
pp. 200-206 ◽  
Author(s):  
Chao Wang ◽  
Heyang Yu ◽  
Ni Zhan ◽  
Xubing Kang ◽  
Jingyu Zhang
Keyword(s):  
Mass Flow Rate ◽  
Natural Frequency ◽  
Mass Flow ◽  
Flow Rate ◽  
Spectral Peak ◽  
Flow Rate Measurement ◽  
Average Amplitude ◽  
Two Phase ◽  
Content Type ◽  
Probe Sensor

Purpose The purpose of this paper is to develop a new vibration probe sensor for measurement of particle mass flow rate in gas–solid two phase flow. Design/methodology/approach A new vibration probe sensor based on polyvinylidene fluoride (PVDF) piezoelectric film is designed. The particle impact model according to Hertz contacting theory is presented. The average amplitude, standard deviation and spectral peak at the natural frequency of the probe (21.2 kHz) of the signals acquired through experiments are chosen as characteristic quantities for further analysis. Findings Through experimental study of relation between three characteristic quantities and the mass flow rate and air flow velocity, a good regularity is found in the average amplitude and the spectral peaks at natural frequency of the probe. According to the particle impact model, the structure of quantitative model is built and parameters of two models are calculated from experimental data. Additionally, tests are made to estimate mass flow rate. The average errors are 5.85 and 4.26 per cent, while the maximum errors are 10.81 and 8.65 per cent. The spectral peak at natural frequency of the probe is more applicable for mass flow rate measurement. Practical implications The sensor designed and the quantitative models established may be used in dilute phase pneumatic conveying lines of coal-fired power plants, cement manufacturing facilities and so on. Originality/value First, the new sensor is designed and the quantitative models are established. Second, the spectral peak at natural frequency of the probe is found that can be used for measurement of mass flow rate.

Assessment of Dimensionless Correlations for Prediction of Refrigerant Mass Flow Rate Through Capillary Tubes — A Review

2017 ◽  
Vol 25 (04) ◽  
pp. 1730004 ◽  
Author(s):  
Mehdi Rasti ◽  
Ji Hwan Jeong
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Capillary Tube ◽  
Capillary Tubes ◽  
Two Phase ◽  
Comprehensive Review ◽  
Wide Range ◽  
Inlet Conditions ◽  
Dimensionless Correlations

Capillary tubes are widely used as expansion devices in small-capacity refrigeration systems. Since the refrigerant flow through the capillary tubes is complex, many researchers presented empirical dimensionless correlations to predict the refrigerant mass flow rate. A comprehensive review of the dimensionless correlations for the prediction of refrigerants mass flow rate through straight and coiled capillary tubes depending on their geometry and adiabatic or diabatic capillary tubes depending on the flow configurations has been discussed. A comprehensive review shows that most of previous dimensionless correlations have problems such as discontinuity at the saturated lines or ability to predict the refrigerant mass flow rate only for the capillary tube subcooled inlet condition. The correlations suggested by Rasti et al. and Rasti and Jeong appeared to be general and continuous and these correlations can be used to predict the refrigerant mass flow rate through all the types of capillary tubes with wide range of capillary tube inlet conditions including subcooled liquid, two-phase mixture, and superheated vapor conditions.

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