Real-time Flow Rate Research Articles

Waste heat and water recovery from natural gas boilers: Parametric analysis and optimization of a flue-gas-driven open absorption system

The open absorption system can recover water and latent heat from industrial flue gases with a higher return water temperature than conventional condensing boilers. In spite of the high efficiency, there are still a lot of unsolved problems in real applications, including the steady operation control and the optimal parameter selection. In this paper, we established a whole-cycle simulation model of a flue-gas-driven open absorption system, which was validated by various experiments to be capable of predicting the operating states of every working fluid for all kinds of actual conditions. Based on this model, we analyzed the actual performance of the system with varying temperatures, flow rates and humidity in a large range. We found that the balance between the vapor absorption and vapor generation is crucial for the optimal operation of the system. The real-time flow rate of the circulating solution should be adjusted with the varying working conditions to achieve the optimal system performance. We further proposed an optimized system based on the theoretical analysis, which can enhance the overall performance by redistributing the circulating solution within the system. The optimized scheme was well demonstrated by experiments with different flue gas humidity ratios. Compared with the original system, the heat recovery and the water recovery of the optimized one were increased by 3.0–23.8% and 5.1–41.4%, respectively, when the split ratio (flow rate ratio of the regenerating solution and the spraying solution) was varied between 0.8 and 0.2. The whole-cycle simulation results and the proposed optimization scheme will evidently contribute to the efficiency improvement of industrial waste heat recovery.

Modelling and control of vanadium redox flow battery for profile based charging applications

Abstract Batteries are the crucial link in accelerating the penetration of renewables in distributed grid systems. With multiple sources (most of which are intermittent), there is a need to optimize the usage of these energy storage systems. It is vital to have a charging algorithm to intelligently charge the battery, considering the losses and state of health. Several battery charging techniques exist for most of the mainstream batteries such as lithium ion and lead acid batteries. These charging algorithms are developed for specific battery chemistries to optimize the charging operation by controlling the charging current. There has been no specific charging methodology proposed, considering the uniqueness of flow batteries. In this paper a flow battery model is developed to accommodate the implementation of charging protocols by controlling the current and flow rate in real time. The aim is to demonstrate a methodology where different user requirements can be programmed for efficient operation of the battery to perform a given task. The control is established by an intuitive fuzzy logic controller for changing the input variables based on the intrinsic losses, pump power loss and the capacity decay due to the aging of the battery. The need for such a controller to handle different scenarios of operation arises from the vast applicability of large scale energy storage. A simple example of such a system is proposed with demonstrating three operator selectable modes namely Autonomous (A), Energy bias (E) and Time bias (T). In each case, a specific current value and flow rate value is selected by the controller and is fine-tuned during the charging process. The values are tuned for specific modes of operation and different aspects of the battery performance are studied for these modes. This work demonstrates a method to leverage the use of a physical model based system in a high level user interface for controlling flow batteries.

An acoustic method for flow rate estimation in agricultural sprayer nozzles

The cost of current flow rate measurement devices is quite high compared to the cost of low-end microphones. This circumstance, together with the fact that common agricultural sprayers have more than 50 nozzles, makes the use of current flow rate measurement devices cost-prohibitive. That considered, this article examines, by proposing one particular method, the feasibility of using microphones as flowmeters for nozzle tips in agricultural sprayers. The proposed method consists of the following stages: (i) acquisition of the digital acoustic data sequence, (ii) signal preprocessing, (iii) frequency domain transformation using Fast Fourier Transform (FFT) analysis, (iv) in-band power calculation, (v) power normalization, and (vi) regression or curve fitting. This method was assessed in an in-lab sprayer test bench employing 11 commercial nozzle tips at several operating flow rates within or close to those recommended by the manufacturers. The experimental results yielded, for all the tested nozzle tips, average absolute and relative Root Mean Square Error (RMSE) values always below 0.08 liters per minute (lpm) and 5%, respectively, while the overall mean absolute and relative RMSE values were lower than 0.05lpm and 2.5%. Furthermore, for each tested nozzle tip, the Maximum Absolute Error (MAE) was always bounded below 0.3lpm, being the absolute error lower than 0.15lpm for 95% of the time. The accuracies when employing a high-end microphone instead of a low-end one presented no statistically significant differences. These results provide strong evidence of the feasibility of accurately estimating the nozzle tip flow rate in real time based on acoustic signals. Moreover, no significant improvements are to be expected by using a high-end microphone instead of a low-end one. However, there are still some issues that should be tackled in order to enable the application of this method in real agricultural settings.

Research on the dynamic characteristics of a turbine flow meter

In the hardware-in-loop simulation of aero-engine control system where the real fuel regulator is engaged, it's crucial to measure the real-time flow rate. In view of this, a flow meter with high precision and fast response is important. In this paper, modeling and experiments are conducted to verify the dynamic characteristics of a turbine flow meter (TFM). For the modeling part, driving torque and resistance torques are analyzed to derive the kinetic equation of TFM. Simulation with the kinetic equation shows good dynamic performance of TFM. In experiments, a workbench is designed to generate step-type flow and sine-type flow for identification in time domain and frequency domain. Results show that the settling time for TFM is no more than 100ms and its band-with is over 4.61Hz. Compared with the settling time of a main fuel valve and the band-width of a main fuel control loop, that is, 1.2s and 2Hz respectively, TFM is considered to be adaptive to measure the fuel of aero-engine.

Rotor profile design and numerical analysis of 2–3 type multiphase twin-screw pumps

Increasing demands for high-performance handling of fluids in oil and gas as well as other applications require improvements of efficiency and reliability of screw pumps. Rotor profile plays the key role in the performance of such machines. This paper analyses difference in performance of 2–3 lobe combination of twin-screw pumps with different rotor profiles. A-type profile formed of involute–cycloid curves and D-type formed of cycloid curves are typical representatives for 2–3 type screw pumps. The investigation is performed by use of a full 3-D computational fluid dynamics analysis based on a single-domain structured moving mesh obtained by novel grid generation procedure. The real-time mass flow rate, rotor torque, pressure distribution and velocity field were obtained from 3D computational fluid dynamics calculations. The performance curves were produced for variable rotation speeds and variable discharge pressures. The computational fluid dynamics model was validated by comparing the simulation results of the A-type pump with the experimental data. In order to get the performance characteristics of D-type profile, two rotors with D-type profile were designed. The first has the same displacement volume as A-type while the second has the same lead and rotor length as A-type but different displacement volume. The comparison of results obtained with two rotor profiles gave an insight on the advantages and disadvantages of each of them.

Novel application of gas chromatography in measurement of gas flow rate

Real-time volume flow rate of gas component for slowly changing composition mixtures is of chief importance for some special research applications. However, it is always difficult for us to achieve the goal by sophisticated gas flowmeter. In this study, we demonstrate two methods for the problem solution by the flow measurement of acetylene in unsteady gas flow based on online gas chromatography accompanying with a gas mass-flowmeter. For Method 1, high purity methane is applied as an internal standard and the volume flow rate of acetylene is obtained via coherent equations. Method 2 makes fully use of the online gas chromatography automated integration under fixed gas chromatography work conditions. Results have shown that both methods are feasible and effective, and Method 2 is more accurate than Method 1 with relative error less than 0.7%.

The Response of a Heat Loss Flowmeter in a Water Pipe Under Changing Flow Conditions

A heat loss flowmeter for measuring the volume flow rate of water in real time ( $t)$ was formed using two thick film segmented thermistors, range constant voltage (RCV) power supply, acquisition card, PC, and software. The input water temperature $T_{w}(t)$ was measured by a cold thermistor, while the water flow rate $Q(t)$ was determined using the heat loss principle by measuring the self-heated thermistor current $I(t)$ . The flowmeter inertia, stability, and accuracy were measured and analyzed on a flowmeter prototype in real-time and real conditions on the water mains. The flowmeter response was measured for different durations of step input water flow-out functions and intervals between steps. An independent ultrasonic flowmeter was connected in series with the thermal flowmeter to measure the ordered input water flow functions. The realized intelligent functions in real time were: measuring the input water temperature $T_{w}(t)$ and self-heating temperature $T_{s}(t)$ , auto-selection of RCV supply voltage $U(T_{w})$ , determination and modeling of the water flow rate in real time $Q(t)$ , determination of the water volume $V(t)$ , and determination of the thermal gradient on the self-heating thermistor as a water flow indicator $\Delta R_{s}(t)$ .

Temperature Sensing in Modular Microfluidic Architectures.

A discrete microfluidic element with integrated thermal sensor was fabricated and demonstrated as an effective probe for process monitoring and prototyping. Elements were constructed using stereolithography and market-available glass-bodied thermistors within the modular, standardized framework of previous discrete microfluidic elements demonstrated in the literature. Flow rate-dependent response due to sensor self-heating and microchannel heating and cooling was characterized and shown to be linear in typical laboratory conditions. An acid-base neutralization reaction was performed in a continuous flow setting to demonstrate applicability in process management: the ratio of solution flow rates was varied to locate the equivalence point in a titration, closely matching expected results. This element potentially enables complex, three-dimensional microfluidic architectures with real-time temperature feedback and flow rate sensing, without application specificity or restriction to planar channel routing formats.

Ultra-high speed imaging study of the diesel spray close to the injector tip at the initial opening stage with single injection

This study focused on the primary breakup of spray at the initial injector opening stage at injection to atmospheric conditions. A real-time mass flow rate instrument was first used to study the injection characteristics at the injector opening stage. A long distance microscope together with an ultrahigh speed CCD camera was then employed to study the primary breakup of diesel spray by photography technique with the help of backlighting. The mechanism of the formation of the mushroom shaped spray head was discussed and the laminar flow regime was expected to be the main reason for the resultant shape. During the initial spray stage, the mushroom spray head penetrated almost linearly with respect to time. The quantification of the fuel mass/spray area ratio suggested that the dispersion of the spray is greatly improved within a very short time, which is assumed to be caused by the further opening of injector.

Optical Tomography: The potential of mass flow rate in rice industry

The capability of Optical Tomography (OT) to visualize pipe flow is undeniably beneficial and of utmost importance to solid gas industry. The other striking feature of OT is its ability to measure and analyze real-time mass flow rate (MFR), which enables online monitoring of material weight. This paper addresses the problem posed by online weighing system in rice industry. The current system slows down the overall industrial production by impeding the device operation, and is therefore becoming obsolete. To overcome this drawback, we confirmed that OT has great potential in online weighing process using a polynomial equation. In addition, MFR measurement can gauge weight loss of rice during the enhancement process. Encouragingly, the application of novel MFR technique to accurately monitor weight loss of rice has proven to outperform the existing system in rice industry.

1P1-M03 セルソーティングに向けた実時間流速制御システム

On chip cell analysis is one of important issues in micro technology research area. One approach to control the fluid flow in microfluidic devices for cell analysis is using appropriate pumps. However, it is difficult to control actual flow rate in microfluidic devices due to difficulty to put flow rate sensors in the microfluidic devices. In this work, we develop a real-time flow rate control system using syringe pumps and high-speed vision which can measure actual fluid flow in microfluidic devices. The developed flow-rate control system is verified through microparticle velocity control experiment and microparticle sorting experiments.

Ultra-Fast Displaying Spectral Domain Optical Doppler Tomography System Using a Graphics Processing Unit

We demonstrate an ultrafast displaying Spectral Domain Optical Doppler Tomography system using Graphics Processing Unit (GPU) computing. The calculation of FFT and the Doppler frequency shift is accelerated by the GPU. Our system can display processed OCT and ODT images simultaneously in real time at 120 fps for 1,024 pixels × 512 lateral A-scans. The computing time for the Doppler information was dependent on the size of the moving average window, but with a window size of 32 pixels the ODT computation time is only 8.3 ms, which is comparable to the data acquisition time. Also the phase noise decreases significantly with the window size. Since the performance of a real-time display for OCT/ODT is very important for clinical applications that need immediate diagnosis for screening or biopsy. Intraoperative surgery can take much benefit from the real-time display flow rate information from the technology. Moreover, the GPU is an attractive tool for clinical and commercial systems for functional OCT features as well.

Development and in vitro evaluation of a flow-adjustable elastic drug infusion pump

Passive-type drug infusion pumps have several advantages over active-type pumps including a simple drug chamber structure and relatively high operational stability. However, conventional passive-type infusion pumps also have several limitations compared to active ejection pumps, such as a fixed flowrate and monotonic flow pattern. To enhance the clinical feasibility of using passive-type drug infusion pumps, flow readjustment and flow regulation abilities are needed. This paper proposes a new portable elastic drug infusion pump that integrates the advantages of active and passive infusion pumps to improve clinical feasibility. The proposed infusion pump incorporates a passively driven drug chamber and an actively adjusted flow controller, which can adjust and regulate various target flowrates and adjust the flow pattern in accordance with the patient's time-varying physiological status. The proposed infusion pump uses the contraction force of an expanded elastic membrane to extract the drug from the drug chamber for delivery into the patient's body through an outlet catheter. It also utilizes a flow sensor, a flow resistor, and a motor-driven flow restrictor that can monitor the real-time flowrate through the outlet catheter and automatically regulate the actual flow-rate around the target value. Experiments on the proposed system resulted in actual injection rates of 0.49 +/- 0.03 (mean +/- standard deviation), 0.98 +/- 0.03, 1.49 +/- 0.04, and 1.99 +/- 0.03 ml/h when the target injection rate was set to 0.5, 1.0, 1.5, and 2.0 ml/h, respectively. During the entire period of operation from the fully filled state to the totally empty state, an inner-chamber pressure of >100 mmHg was maintained, which shows that the proposed infusion pump can stably maintain its target flowrate as the amount of drug remaining to be injected decreases. It appears that the proposed drug infusion pump can be applied to a wide variety of patient treatments that require short-term, accurate, and stable drug delivery.

切断用酸素プラズマトーチの電極現象の実験的考察

An experimental study of a torch for oxygen plasma arc cutting (PAC) was conducted. We made a nozzle equipped with a window and a port for measurement. We observed the hafnium (Hf) electrode during working, using a color high-speed video camera through the window. The color image consists of three images assign red (R), green (G) and blue (B). Each image is taken by different image sensors having different wavelength sensitivity. We estimated the temperature on the surface of the Hf electrode assuming the black body radiation of the surface. And the port of the nozzle is connected to a pressure sensor to measure the pressure in the nozzle. We could estimate the real-time flow rate of plasma gas from the difference between the pressure in the nozzle and the pressure of supply.Using the special nozzle for observation, we investigated the arc phenomena of PAC using an Hf electrode, during arc-start and arc-shut-off.

Skeletal muscle contractions uncoupled from gravitational loading directly increase cortical bone blood flow rates in vivo

The direct and indirect effects of muscle contraction on bone microcirculation and fluid flow are neither well documented nor explained. However, skeletal muscle contractions may affect the acquisition and maintenance of bone via stimulation of bone circulatory and interstitial fluid flow parameters. The purposes of this study were to assess the effects of transcutaneous electrical neuromuscular stimulation (TENS)-induced muscle contractions on cortical bone blood flow and bone mineral content, and to demonstrate that alterations in blood flow could occur independently of mechanical loading and systemic circulatory mechanisms. Bone chamber implants were used in a rabbit model to observe real-time blood flow rates and TENS-induced muscle contractions. Video recording of fluorescent microspheres injected into the blood circulation was used to calculate changes in cortical blood flow rates. TENS-induced repetitive muscle contractions uncoupled from mechanical loading instantaneously increased cortical microcirculatory flow, directly increased bone blood flow rates by 130%, and significantly increased bone mineral content over 7 weeks. Heart rates and blood pressure did not significantly increase due to TENS treatment. Our findings suggest that muscle contraction therapies have potential clinical applications for improving blood flow to cortical bone in the appendicular skeleton.

Real time mass flow rate measurement using multiple fan beam optical tomography

This paper presents the implementing multiple fan beam projection technique using optical fibre sensors for a tomography system. From the dynamic experiment of solid/gas flow using plastic beads in a gravity flow rig, the designed optical fibre sensors are reliable in measuring the mass flow rate below 40% of flow. Another important matter that has been discussed is the image processing rate or IPR. Generally, the applied image reconstruction algorithms, the construction of the sensor and also the designed software are considered to be reliable and suitable to perform real-time image reconstruction and mass flow rate measurements.

Instant hemodynamics circumstance study in arterial stenosis under math modeling of external counterpulsation

目的 研究体外反搏对局部狭窄动脉内血流动力学环境的影响,进而探讨体外反搏对动脉粥样硬化斑块的干预作用.方法 设计了一个基于流体动力学理论的数学模型,在特定的空间坐标系下推导了描述血液脉动流的控制方程,给出了合适的边界条件,并设计了数值算法对模型进行求解.以雄性乳猪的颈动脉为对象,在体测量了动脉的几何参数及反搏前后心动周期内连续的流率、动脉内压和心电.通过将反搏前后的实测数据分别应用到文中建立的数学模型中进行求解.结果 得到了反搏前后心动周期里动脉模型内的多种重要的血流动力学量,包括血液流场、速度分布、壁面切应力(WSS)分布等.结论 体外反搏能有效提高心动周期内动脉的血流量、提高心动周期内尤其是舒张期的动脉内壁切应力水平及压力梯度、增加动脉局部狭窄段后端回流区的血液回流速度.这些改变对于动脉粥样硬化斑块的发生及发展都有良好的干预作用。

Evaluation of Flow-Based Traffic Signal Control Using Advanced Detection Concepts

State-of-the-practice signal timing techniques used at isolated actuated controlled intersections can result in suboptimal operation. This paper proposes a new tactical control algorithm that integrates real-time stop bar presence detection with real-time flow rate information to identify a downstream flow restriction. If a flow restriction is identified, a phase with a constant call could be terminated earlier than its specified maximum or split time. This algorithm was validated with real-time data to predict downstream bottleneck conditions and then by viewing the archived video for confirmation of the condition. The algorithm was applied during a 504-h period of signal operation. During this period, the algorithm identified 76 bottlenecks. Overall, 75.0% of these events were visually confirmed. Algorithm failures were caused by a variety of conditions such as large trucks, inattentive drivers, and detector errors.

Evaluation of Flow-Based Traffic Signal Control Using Advanced Detection Concepts

State-of-the-practice signal timing techniques used at isolated actuated controlled intersections can result in suboptimal operation. This paper proposes a new tactical control algorithm that integrates real-time stop bar presence detection with real-time flow rate information to identify a downstream flow restriction. If a flow restriction is identified, a phase with a constant call could be terminated earlier than its specified maximum or split time. This algorithm was validated with real-time data to predict downstream bottleneck conditions and then by viewing the archived video for confirmation of the condition. The algorithm was applied during a 504-h period of signal operation. During this period, the algorithm identified 76 bottlenecks. Overall, 75.0% of these events were visually confirmed. Algorithm failures were caused by a variety of conditions such as large trucks, inattentive drivers, and detector errors.

Throughput guarantees for multi-priority traffic in ad hoc networks

In this paper, we present MPARC (Multi-Priority Admission and Rate Control), a novel joint admission control and rate policing protocol for multi-priority ad hoc networks. MPARC is based on our novel bandwidth allocation model, which captures the bandwidth allocation for saturated, unsaturated and semi-saturated networks. MPARC guarantees that the throughput of admitted realtime flows will not decrease due to later arriving realtime flows with equal or lower priorities or due to best effort flows. MPARC achieves this goal by performing accurate admission control on every newly arriving realtime flow and appropriate rate policing on all best effort traffic. Through simulation, we demonstrate that MPARC has better performance than existing approaches.