Mass Flow Rate Measurement Research Articles

Capacitance-based mass flow rate measurement of two-phase hydrogen in a 0.5 in. tube

Mass flow rate is a critical measurement parameter when designing cryogenic hydrogen fluid systems. It is important in custody transfer applications for calculating financial obligations, fundamental fluid property research/modeling, and fluid system design applications to optimize chill down performance, maintain thermal equilibriums, and provide feedback control for pumps and valves. However, due to the large temperature differential between cryogenic fluids and the environment, there is often multiphase flow during system chilldown and steady state operation. Current available cryogenic flow measurement techniques are not equipped to deal with the complex multiphase flow inherent in cryogenic fluid systems, resulting in significant measurement errors. This mass flow measurement inaccuracy can cause financial loss, system instability, and even component failure, resulting in a strong market demand for a multiphase cryogenic mass flow meter to optimize and control sophisticated and costly cryogenic systems. This paper presents a solution in the form of a novel capacitance-based technique for measuring the multiphase mass flow rate of cryogenic hydrogen in a terrestrial environment. The device was calibrated and tested on a ½” tube multiphase hydrogen flow loop at a cryogenic hydrogen test facility. An error of ± 2 % full scale was achieved across a range of flow conditions, including transient and steady states.

Online mass-flow-rate measurement of high-intensity gas-conveyed particle flow for dry mineral processing

Measuring the mass flow rate of high-intensity gas-conveyed particle flow (GCPF) in real time is of great importance for enhancing efficiency and productivity in dry mineral processing circuits. It also poses challenges beyond the capability of most existing technologies. In this article, we introduce a novel, cost-effective, online mass flow rate measurement system utilizing a force transducer. A theoretical model of the relationship between the average impact force and the mass flow rate was developed using the Hertz theory of impact. A prototype sensing system was then designed and constructed, followed by a series of experiments to validate the theoretical model. The experimental results corroborated the proposed model and showed the accuracy of the measurement was within 2% for mass flow rates above 1.741 g/s. This demonstrated the system’s capability to measure the mass flow rate of GCPF in real-time using measurements of the average impact force.

Quantitative analysis of hydrogen leakage flow measurement and calculation in the on-board hydrogen system pipelines

The mass flow rate of hydrogen leakage directly affects hydrogen diffusion and concentration distribution. In this paper, a test platform was constructed to measure mass flow rates during hydrogen leakage in the supply pipelines of the on-board hydrogen system. Hydrogen leakage tests were conducted under two different conditions. Mass flow rates were measured for tube fittings with various loosening angles and hydrogen supply pressures. The data were then fitted to extrapolate mass flow rates of hydrogen leakage beyond the tested conditions. Additionally, mass flow rates were measured for hydrogen supply pipelines with small holes of different shapes and sizes. The effects of pipeline size, hydrogen supply pressure, hole shape, and size on the hydrogen leakage mass flow rate were analyzed. Hydrogen leakage flow coefficients were corrected, and the accuracy of three calculation methods for hydrogen leakage flow was compared and analyzed based on the test results. The results provide a foundation for future numerical simulation models of hydrogen leakage diffusion.

A New Development of Cross-Correlation-Based Flow Estimation Validated and Optimized by CFD Simulation

The accurate measurement of mass flow rates is important in nuclear power plants. Flow meters have been invented and widely applied in several industries; however, the operating environment in advanced nuclear power plants is especially harsh due to high temperatures, high radiation, and potentially corrosive conditions. Traditional flow meters are largely limited to deployment at the outlet of pumps, on pipes, or in limited geometries. Cross-correlation function (CCF) flow estimation, on the other hand, can estimate the flow velocity indirectly without any specific instruments for flow measurement and in any geometry of the flow region. CCF flow estimation relies on redundant instruments, typically temperature sensors, in series in the direction of flow. One challenge for CCF flow estimation is that the accuracy of the flow measurement is mainly determined by inherent, common local process variation across the sensors, which may be small compared to the uncorrelated measurement noise. To differentiate the process variations from the uncorrelated noise, this research implements periodic fluid injection at a different temperature than the bulk fluid before the temperature sensors to amplify process variation. The feasibility and accuracy of this method are investigated through flow loop experiments and Computational Fluid Dynamics (CFD) simulations. This paper focuses on a CFD simulation model to verify the previous experimental results and optimize CCF flow estimation with different configurations. The optimization study is carried out to perform a grid search on the optimal location of the sensor pair under different flow rates. The CFD results show that the optimal sensor spacing depends on the flow rate being measured and provides guidance for sensor location implementation under various anticipated flow rates.

The development of the ultrasonic flowmeter sensors for mass flow rate measurement: A comprehensive review

A two-phase flow measuring device whose measurement system does not disturb the flow pattern, real-time measurement, and non-destructive measurement or non-intrusive model is a typical tool for an ideal situation. One measuring instrument that meets these criteria is an ultrasonic flow meter. Ultrasonic sensors can measure the velocity of fluid flow in pipelines. It has the advantage of high accuracy and reproducibility and does not make direct physical contact with the fluid in the pipe. Low fabrication costs and fast response make ultrasonic flowmeters widely used for two-phase flow measurements in both horizontal and vertical orientations. The void fraction or liquid holdup and velocity are the two most essential parameters for flow monitoring. The Time of Flight (ToF) method is mainly used for measurements in several ultrasonic flowmeter methods. In the present manuscript, the introductory section of this review explains the advantages of using the Time of Flight (ToF) method and its basic principles. This review also discusses research on measuring velocity and flow rate, differences in intrusive and non-intrusive measurement methods, parameters that affect ultrasonic measurements, and finally, measuring film thickness using non-intrusive methods.

Tuning hydrogen boil-off via inert gas insulation purge in a vapor cooled shielded fuel tank

Vapor cooled polymer composite tanks for liquid hydrogen are a newopportunity for light weight power-system integration into unmanned aerial vehicles. Vapor shielding has the ancillary benefit of pre-conditioning the hydrogen for use by a fuel cell. However, the mass flow rate required by a fuel cell should be matched by the natural boil-off rate of the tank. With limited ability to vary insulation thicknesses, the challenge becomes satisfying the fuel cell consumption in UAVs at different mass flow rates when at varying stages of flight from take-off, cruise, and landing. This paper provides experimental measurements of mass flow rate of hydrogen from the tank considering batch purging with helium or argon in the vapor cool shielded insulation layer. A 5-shell vapor cooled shielded tank is used with two layers of insulation including aerogel, helium or argon, and two vapor channels. A more complete understanding of system-level thermal conductance is determined by mass flow of hydrogen leaving the tank during hypothetical flight.

Capacitance-based measurement of volume fraction, velocity, and mass flow rate of cryogenic nitrogen two-phase flow

Cryogenic fluid flow is a critical measurement parameter but is difficult to properly measure due to the extreme environmental conditions and the frequent presence of multiphase flow during saturated liquid transfers. Multiphase flow proves challenging for most flow measurement methodologies; furthermore, additional measurements of volume fraction, quality, and slip velocity are often required. In-line capacitance-based sensors have the potential to overcome these limitations. In this paper, a capacitance sensor in a multiphase cryogenic flow loop is evaluated for its ability to measure liquid volume fraction, gas phase velocity, and total mass flow rate for two-phase cryogenic nitrogen flow.

A fusion algorithm for mass flow rate measurement based on neural network and electrical capacitance tomography

The process tomography has received a noticeable attention in industry due to non-invasive and non-intrusive characterise. To asses the potential of electrical capacitance tomography for gravity-fallen mass flow rate measurement, a fusion algorithm based on neural network is designed and implemented. The hardware of instrument is composed of a pipe as circular phantom with 200 mm internal diameter and the front-end electronics. The specially programmed software, runs five well-known, non-iterative reconstruction algorithms (LBP, Tikhonov, SVD, ART and SIRT) and fusions the results in a MLP-NN. The sensor experimentally evaluated by wheat grains. Five implemented algorithms, and the fusion NN are compared using RMSE and concentration error parameters. According to evaluated results in whole of tests, the fusion algorithm reduces RMSE and concentration error by approximately 2–3 and 7–10 folds respectively. Since these five algorithms are completely independent, running the program in parallel by Multi-Thread mode, do not adds run-time.

Variations in gas temperature and average velocity during laminar-turbulent transition in high-speed gas flow through microtubes

The primary objective of this study is to investigate variations in gas temperature and average velocity during the laminar-turbulent transition of compressible flow. This investigation encompasses an exploration of the effect of Mach number on transitional Reynolds number. Experiments were conducted utilizing a pair of adiabatic stainless steel microtubes with a diameter (D) of 131.6 μm. The first microtube was dedicated to measuring local pressure to obtain friction factor, local Mach number, and bulk temperature. The second microtube was employed for measuring local wall temperature. Additionally, a stainless steel microtube with a diameter (D) of 124 μm and a rectangular microchannel with a hydraulic diameter (Dh) of 99.36 μm were incorporated in the study. Friction factor, Mach number, and bulk temperature were determined by measuring mass flow rate and local pressure near the outlet. The measured mass flow rate exhibited a slight increase that plateaued during the laminar-turbulent transition as the Reynolds number increased. In laminar flow, an increase in the Reynolds number resulted in an increase of the Mach number and a reduction in bulk temperature. Conversely, during the laminar-turbulent transition, the Mach number either remained constant or decreased, and the bulk temperature increased due to the conversion of kinetic energy to thermal energy. Experimental validation of this phenomenon was achieved by measuring the wall temperature of an adiabatic microtube.

The steady behavior of the supercritical carbon dioxide natural circulation loop

The steady state behavior of thermodynamically supercritical natural circulation loops (NCLs) is investigated in this work. Experimental steady state results with carbon dioxide are presented for supercritical pressures in the range of 80–120 bar, and temperatures in the range of 20–65 °C. Distinct thermodynamic states are reached by traversing a set of isochors. An equation for the prediction of the steady state of NCLs at supercritical pressures is presented, and its performance is assessed using empirical data. Changes of mass flow rate as a result of independent changes of thermodynamic state, heating rate, driving height and viscous losses are shown to be accurately captured by the proposed equation. Furthermore, close agreement between the predicted and measured mass flow rate is found when the measured equipment losses are taken into account for the comparison. Subsequently, the findings are put forward in aid of the development of safe, novel supercritical natural circulation facilities.

Experiments on capacitance based liquid flow meter with parallel channels used in two-phase

A new flow meter has been proposed to measure liquid mass flow rate in a two-phase system. Irrespective of the input flow, the proposed system transforms incoming stream into laminar stratified flow. This configuration offers a promising avenue for assessing liquid flow rates in a two-phase system by leveraging measurements of liquid column height. Extensive performance assessments have been conducted for different vapour and liquid flows. Since the fluid properties are taken into consideration for designing the system, the temperature dependence on the performance of the flow meter also has been studied. The outcome of these studies has yielded a robust correlation between the actual liquid flow rate and the value deduced from the observed liquid column height. The correlation developed between the actual liquid flow rate and that determined from the height of fluid was accurate with an error of ± 3.8 %. It is also found that this flow meter is capable enough to determine the changes in flow conditions with temperature and would provide flow measurements within an error of ± 4 %. This novel two-phase flow meter not only advances the precision of liquid mass flow rate measurements but also demonstrates its adaptability in accommodating changing flow conditions, particularly those driven by temperature dynamics. The findings presented herein underscore the potential of this innovative flow meter as a reliable tool for accurate flow rate determination in diverse industrial applications such as cryogenics, superconductivity, etc.

Throttling simulation and control of liquid oxygen/liquid methane rocket engine pressurized by the electric pump

This article presented simulation and control of a liquid oxygen/liquid methane variable thrust rocket engine pressurized by the electric pump in the throttling process. To get a proper injection pressure drop, the variation of the injection area was investigated and determined. In the control scheme, the combustion pressure and mixture ratio were the targets. To simplify the control scheme, the pressure and mixture ratio were correlated to the oxygen mass flow rate and methane mass flow rate, respectively. By controlling the propellant mass flow rate, the target engine thrust was reached. In addition, the influence of mass flow rate measurement points on the control effect was analyzed. The simulation results showed that the designed controller can reduce the overshoot of the critical engine parameters. Therefore, the maximum temperature of the thrust chamber wall after the regenerative cooling was decreased. Consequently, the thrust control errors were within 3% except for the points where the thrust changed suddenly, which can meet the mission requirements.

Online Measurement of Wet Gas Mass Flowrate Based on Averaging Pitot Tube-Vortex Integrated Sensor

Online Measurement of Wet Gas Mass Flowrate Based on Averaging Pitot Tube-Vortex Integrated Sensor

Modeling of contact thermal resistance in lateral capillary tube-suction line heat exchangers with experimental validation and investigation

This paper studied the lateral capillary tube-suction line heat exchanger (CTSLHX) with different contact types and different geometries. An improved one-dimensional model of the CTSLHX was established, using the CFD model to derive the contact thermal resistance between the capillary tube and the suction tube. An experimental bench was built to test the steady-state heat transfer and flow performance. It was found that the model predicted 87.6 % and 98.9 % of the measured mass flow rate within the error band of ± 10 % and ± 15 %. The prediction error of the CTSLHX heat transfer effectiveness was within ± 10 %. Parametric effects of different operating conditions and structural parameters on the performance of CTSLHX were investigated. Furthermore, experiments were carried out to study the temperature distribution along the transition section between the exit of the capillary tube and the evaporator. The unique temperature increase reveals that it is beneficial for reducing noise by wrapping a layer of rubber around the second increaser fitting.

A new type of velocity averaging tube vortex flow sensor and measurement model of mass flow rate

Accurate mass flow rate measurement of fluid is one of the key technologies to ensure product quality and utilization of energy resources. However, the accuracy of traditional combined measuring devices is limited. In this paper, a new type of velocity averaging tube vortex flow sensor (VATV) is designed, and the mass flow rate measurement model is proposed and analyzed to achieve the high precision measurement of mass flow rate. The size, shape and structure of the VATV are designed in this study and there are no moving parts inside the integrated VATV. The method of double differential pressure is proposed to achieve the measurement of the average differential pressure signal and differential pressure fluctuation signal. Then, the method of Empirical Wavelet Transform (EWT) is used to extract the vortex shedding frequency from the differential pressure fluctuation signal. It indicated that the proposed VATV achieves an accuracy of ±0.50%, and the repeatability is also lower than 0.07%. A remarkable improvement of accuracy is achieved compared to the original combined measurement devices. The proposed sensor shows good prospect for the detection of gas-liquid two-phase flow such as wet stream due to the feature of strong anti-interference, high stability and reliability.

Statistical and machine learning application approach to predict mass flowrate

Flow measurement is one of the critical points in the industrial process measurement. Mass flow measurement, as an alternative flow measuring method, is usually chosen to prevent temperature effects to the density that would be impacted directly to the flow measurement. One of the most popular direct mass flow measurements is Coriolis Mass Flowmeter (CMF). CMF which has an accuracy of mass flow measurement up to 0.1% of reading, recently became widely used for valuable fluids mass flowrate measurement. The challenge of the flow measurement will not stop in the selection and the smart capabilities of the flow instrument itself; another issue that appears during process measurement is the absence of the installed CMF as a mandatory installed, local pressure measurement could be a physical parameter that could be used to predict the mass flowrate using statistical and machine learning algorithms. This virtual flow measurement method will be an approach to face the absence of physical flowmeter issues, especially in critical or remote operation processes.

Aerodynamic design and experimental study of small flow rate centrifugal compressor

The aerodynamic design of a single-stage of a small flow rate centrifugal compressor is completed by theoretical analysis and CFD simulation, and the simulation results can meet the target performance. In addition, an equal proportion prototype performance test bench was designed and built, and the prototype performance test using air as working medium was completed. The results show that the overall trend of the measured flow-pressure ratio curve fits well with the simulation curve. Due to the error of simulation calculation, the measured mass flow rate is a little small and there is a certain difference with the simulation data. Based on the results, the structure of impeller and volute was optimized, and the performance was retested. The retest results show that the flow range of the measured pressure ratio and efficiency curve can basically cover the simulated curve, and the difference between the measured value and the simulated value of pressure ratio and efficiency decreases significantly. Using air medium, when the mass flow is 0.01kg/s, the pressure ratio is 1.17 and the isentropic efficiency is 85%. The results confirm the feasibility of this design method, which can provide important reference for the design of small-flow centrifugal compressor.

On the Use of Ultrasonic Flowmeters for Cooling Energy Metering and Sub-Metering in Direct Expansion Systems

The Energy Efficiency Directive (EED, Directive 2012/27/EU) has made mandatory the installation of individual metering systems in the case of buildings with centralized heating/cooling and hot water sources (multi-apartment and multi-purpose buildings), provided it is economically and technically feasible. Individual metering of heating/cooling systems is mainly based on thermal energy meters (TEM), which are widely used for direct metering in heating applications. On the other hand, direct metering of energy consumption in cooling systems still represents a challenge, given the different types of cooling units and the lack of regulations from the technical and legal points of view. In this context, this paper briefly overviews the available centralized cooling systems and the possible solutions for metering and sub-metering, which depend on the specific application. Vapour Compression Refrigeration (VCR) systems are spreading worldwide for air conditioning applications. Particular attention has been paid to the direct metering of cooling energy and specifically to refrigerant flow rate measurement, which represents a critical issue because of the small-diameter pipes and the different thermodynamic properties of the fluid used. Thus, an experimental campaign has been developed and carried out in order to compare a clamp-on ultrasonic flowmeter with a more accurate Coriolis one in a direct expansion (DE) system. The experimental tests have been performed at two different temperature conditions, showing a relative error in the mass flow rate measurements within ±10%.

Laboratory and field validation of a new Coriolis metering concept for better measurement uncertainty, reliability and process insight

Coriolis mass flowmeters are widely accepted in various industries for their high performance measurement of density and mass flow rate. Not only do they play a critical role in O&G custody transfer applications, they are also increasingly important in addressing the new challenges and applications related to the energy transition where the highest accuracy and reliability is also required. Analogous to multi-beam Ultrasonic flowmeters, a new measuring concept based on the Coriolis principle has been developed with a metering system consisting of two individual Coriolis meters arranged in parallel to measure the incoming flow into the overall system. There are numerous advantages of this arrangement, among which reducing measurement uncertainty, increasing reliability and gaining greater process insights are the most significant addressed in this paper. Statistic theory suggests that for a total measurement equally divided by two sub-measurements of two independent measuring devices, the measurement uncertainty caused by random errors is reduced by a factor of the square root of 2 for the combined total measurement if the two sub-measurements are not correlated. This advantage applies to the zero-point and repeatability performance of the metering system. Taking advantage of independently measuring the same or similar fluid parameters twice, the measurement reliability is enhanced by cross-checking the two sets of measured parameters. For certain special cases, such as the transient disturbance caused by entrained gas that often exists under real process conditions, the corresponding negative impact can even be mitigated or eliminated by utilizing the undisturbed measured parameter set from the two. The spacial arrangement of the two Coriolis meters makes it useful to monitor the measured fluid parameters such as two sets of density, flow and temperature values to obtain additional knowledge of the spacial distribution of these fluid parameters, which can provide greater process insights.A critical step has been the validation of the theoretical advantages in third-party laboratories and in the field. A test was done for the zero-point stability of the metering system under various temperatures, pressures and viscosities at NEL using the EPAT facility. The measurement results suggested that the zero-point deviations of the two Coriolis meters followed a random probability and tended to cancel each other to certain degree, leading to a reduced zero-point deviation for the complete metering system. Repeatability and reproducibility tests conducted both at NEL EPAT and at Euroloop oil rigs with provers, showed good and consistent results. Recognizing most hydrocarbon markets trade on a volumetric basis rather than mass, the advantages the design brings towards density measurement are discussed and measurement data is presented across varying fluid densities and viscosities. In step with the growing importance of gaseous fluids associated with the evolving energy markets, the influence the novel design has on performance in gas applications is described and measurement data in gases is also presented. Furthermore, an interesting phenomenon has been captured during the flow stabilization phase before proving at Euroloop that transient disturbance of gas bubbles could be present, and very often disturbed only one of the two measuring systems at the same time, which enables the possibility to remediate the effect of transient disturbances. The same phenomenon was observed in field tests of this novel metering system, indicating the high probability of the occurrence. In this paper, the laboratories data from the NEL EPAT rig, Euroloop rig, pigsar rig, and H&D Fitzgerald as well as the data from field applications are presented and analysed to validate the theoretical analysis.

Experimental Assessment of Correlative Approaches for the Prediction of Leakage Flow through Labyrinth Seals

Simple analytical models can be employed to estimate the leakage mass flow rate from labyrinth seals, resulting in a quick procedure, well suited for the early design process. Different formulas were proposed by many authors during the past decades and most of them employ a carry-over factor and a flow coefficient to predict the mass flow rate across the clearance area. The present work aims to compare the analytical prediction with the results of an experimental campaign. The experimental results were retrieved from a dedicated test rig for both a straight-through and a stepped labyrinth seal. Hence, for each seal, the effect of the clearance size, the Reynolds number and the pressure ratio has been investigated. Starting from the experimental required inputs, six different correlations are considered, with both direct and indirect methods. The results are shown as a function of pressure ratio and clearance gap. Despite some differences in the comparison, and most of the used correlation underestimate the measured mass flow rate, some general trends and guidelines can be highlighted.