Thermal Flow Meter Research Articles

Design and Analysis of a Thermal Flowmeter for Microfluidic Applications: A Study on Sensitivity at Low Flow Rates

To address the challenge of precise flow rate measurement in microchannels, this research details the conceptualization and comprehensive evaluation of a thermal flowmeter which works on the principle of calorimetry for measuring small flow rates between 0.1 and 180 mL/h. The thermal flowmeter is composed of a silicone pipe, a heater, three platinum thermal sensors (T1, T2, T3), and water as the working fluid. The flowmeter is strategically placed to monitor the complex thermodynamics between upstream and downstream flows. The analysis revealed a notable decay in the slope of the temperature differences beyond a flow rate of 40 mL/h, indicating the exceptional sensitivity of the device at lower flow rates and making it an ideal choice for medical applications. Parametric analysis was also carried out to place the sensors at optimized locations for better sensitivity.

Numerical analysis of heat transfer and flow characteristics of the satellite thermal flowmeter and exploration of high-precision calibration methods

The performance of the thermal flowmeter for satellites is numerically studied to optimize. Flow patterns and temperature distributions, affected by buoyancy convection, significantly influence the accuracy of flow-rate measurements in inclined thermal flowmeters. The present study delves into the thermal flowmeter’s flow field and temperature distribution influenced by gravitational effects. When the Reynolds number is low, buoyancy convection causes a significant inconsistency in the measurement result between ground and space. By eliminating the constraint of the symmetrical arrangement of thermocouples and introducing additional thermocouples for high-precision calibration, the measurement accuracy is remarkably improved. Ultimately, arranging the thermocouples asymmetrically reduces the error by 62%. Additionally, integrating two more thermocouples is even more beneficial, reducing the error by 83% compared to the previous study. These improvements would be potential solutions of flow-rate measuring inconsistency between ground and space, aiding the development of a high-precision thermal flowmeter for satellites.

Research on thermal mass flowmeter (TMF) measurement of coalbed methane (CBM) well production profile.

Developing coalbed methane (CBM) aligns with global climate change policies and sustainable energy development. Currently, methods for testing gas and water production profiles in CBM wells are diverse. A downhole constant-flow thermal mass flowmeter (TMF) was designed to address the difficulty of testing gas production above the liquid level in low-yield CBM wells. A computational fluid dynamics model with a 125mm diameter pipe was established to study the TMF's temperature field and thermal equilibrium time as the gas flow rate changes. The relationship curve between temperature, thermal equilibrium time, and flow rate changes was obtained. The effect of the TMF's installation angle and position in the wellbore on resolution was discussed. Experimental research on a multiphase flow simulation apparatus showed that the TMF has good response capability and testing accuracy in a gas environment. Measuring downhole flow rates using the thermal flow meters is feasible and meets the testing requirements of CBM wells.

Spatial assessment of pollutants concentration in air and soils impacted by industrial wastes in lagos state, Nigeria

The mega city of Lagos, Nigeria is plagued by various environmental issues, chief amongst them being environmental pollution induced by poor and disjointed urban industrial waste management practices. This study aimed to identify and quantify the types of urban industrial waste generated in Lagos State. The State plays host to the largest population base in Nigeria with over twenty million people. The study adopted a quasi-experimental design. Soil, industrial waste generation and pollutant levels were determined with the aid of a thermal mass gas flow meter. Industrial wastes were measured in situ using a weighting scale, while surface soil samples were collected at depths of 0–30 cm. Results show that 20% of the industrial waste generated in the metropolis was ignitable (possibility of spontaneous combustion). The results were thereafter compared with international standards on the permissible limits for various pollutants in air and soil of Lagos State. Ikorodu had the greatest contribution of industrial waste generated in Lagos, followed by Ikeja, Oshodi, Ojo/Alaba and Surulere. The implications of these results and findings is that a lot needs to be done in terms of appropriate legislation, enforcement and tracking of industrial waste generation in Lagos State for effective monitoring and implementation of management strategies.

On the Design of a Non-invasive Thermal Flowmeter

We present the design for an efficient, non-invasive thermal flowmeter. Accuracy tests for the flowmeter are performed. The flowmeter is optimized to measure the minimum velocity possible.

Instantaneous sap flow velocity simulation of Euonymus bungeanus based on neural network optimization model.

The sap flow of trees is complex and difficult to express with multivariate linear or empirical models. A simple and feasible method on the basis of understanding sap flow variation to simulate its variation with environmental factors is of special importance for quantitatively analyzing forest ecohydrological processes and regional water demand. In this study, with one of the shelter forest species Euonymus bungeanus in the east sandy land of Yellow River in Ningxia as the research object, we continuously measured the trunk sap flow velocity by thermal diffusion sap flow meter, and analyzed the effects of environmental factors on stem sap flow. We used the particle swarm optimization (PSO) and sparrow search algorithm (SSA) optimized neural network model to predict sap flow velocity of E. bungeanus. Results showed that the main environmental factors influencing sap flow were solar radiation, vapor pressure deficit, air temperature, and relative humidity, with the influencing importance of 32.5%, 25.3%, 22.0% and 16.1%, respectively. The response process between sap flow and environmental factors presented a hysteresis loop relationship. The optimized BP, Elman and ELM neural network models improved the comprehensive evaluation index (GPI) by 1.5%, 30.0% and 5.3%, respectively. Compared with the PSO-Elman and SSA-ELM optimization models, the SSA-BP optimization model had the best prediction results with an improvement of 1.0% and 23.2% in GPI, respectively. Therefore, the prediction results of the BP neural network model based on the sparrow search algorithm could be used as an optimal model for predicting instantaneous sap flow velocity of E. bungeanus.

Thermal Flow Meter with Integrated Thermal Conductivity Sensor.

This paper presents a novel gas-independent thermal flow sensor chip featuring three calorimetric flow sensors for measuring flow profile and direction within a tube, along with a single-wire flow independent thermal conductivity sensor capable of identifying the gas type through a simple DC voltage measurement. All wires have the same dimensions of 2000 μm in length, 5 μm in width, and 1.2 μm in thickness. The design theory and COMSOL simulation are discussed and compared with the measurement results. The sensor's efficacy is demonstrated with different gases, He, N2, Ar, and CO2, for thermal conductivity and thermal flow measurements. The sensor can accurately measure the thermal conductivity of various gases, including air, enabling correction of flow rate measurements based on the fluid type. The measured voltage from the thermal conductivity sensor for air corresponds to a calculated thermal conductivity of 0.02522 [W/m·K], with an error within 2.9%.

Numerical Study on Characteristics of Convection and Temperature Evolution in Microchannel of Thermal Flowmeter.

During practical usage, thermal flowmeters have a limited range of applications. The present work investigates the factors influencing thermal flowmeter measurements and observes the effects of buoyancy convection and forced convection on the flow rate measurement sensitivity. The results show that the gravity level, inclination angle, channel height, mass flow rate, and heating power affect the flow rate measurements by influencing the flow pattern and the temperature distribution. Gravity determines the generation of convective cells, while the inclination angle affects the location of the convective cells. Channel height affects the flow pattern and temperature distribution. Higher sensitivity can be achieved with smaller mass flow rates or higher heating power. According to the combined influence of the aforementioned parameters, the present work investigates the flow transition based on the Reynolds number and the Grashof number. When the Reynolds number is below the critical value corresponding to the Grashof number, convective cells emerge and affect the accuracy of flowmeter measurements. The research on influencing factors and flow transition presented in this paper has potential implications for the design and manufacture of thermal flowmeters under different working conditions.

Research on Liquid Flow Measurement Method Based on Heat Transfer Method

Thermal flowmeters are used more and more widely in liquid flow measurement. In this paper, the mechanical shape of the thermal flowmeter is designed, and the optimal installation position of the thermal probe is determined. In the aspect of measurement mechanism research, three heating methods of the thermal probe are deduced: constant voltage heating method, constant current heating method, and constant power heating method. After reasoning, the constant current heating method is determined to be ideal, so the constant current heating method is selected to heat the speed-measuring probe in the experiment. By analyzing the power factor of convection heat transfer and residual heat source of the heating probe, it is concluded that the measurement range of the thermal flowmeter is 0.5–15 m3/d, the flow in this range is proportional to the electrical signal, and the relative error of measurement is within ±5.8%. According to the analysis of the experimental results, the thermal flowmeter has a simple mechanical structure and no redundant moving parts, which can prolong its service life when used on site. When considering industrial applications, the error may be greater than the laboratory error.

Optimal Design Parameters of Thermal Flowmeter for Fuel Flow Measurement.

The article analyses the influence, relationship and value of the design parameters of the thermal flowmeter on its radial and axial heat fluxes in the tube. The purpose of the analyses is to check the change in the error of fuel flow measurement by the thermal flowmeter directly on the vehicle when using heating elements of different diameters. The influence of the radial heat flux of the flowmeter tube on the accuracy of fuel flow measurement is substantiated. Recommendations on the choice of design parameters of a thermal flowmeter at the stage of its design, development or use are developed under the condition of reducing the influence of the radial heat flow on the axial one, which will reduce the total error in the measurement of fuel flow rate.

Research on small flow detection method based on constant power method

In the field of three phase flow testing, real-time and online wellhead production detection has become an indispensable trend for evaluating well production and well condition. At present, the production of most conventional oil fields in China is low, and there are many Wells with less than 10 m3 d−1. It is difficult to detect the flow of low-flow Wells with conventional metering methods. Therefore, this paper proposes to use thermal flowmeter temperature difference method to measure the flow value. First, COMSOL Multiphysics software was used to build the model of the thermal flow meter and set the size of the temperature probe, heating probe and velocity probe. Secondly, relevant parameters are set to simulate two steady state forms with different water content and different flow rate. Finally, the temperature changes of the velocity probe are simulated under the two conditions. The simulation results show that when the water content is the same and the flow velocity is between 0.0059 m s−1 and 0.059 m s−1, the temperature of the probe decreases with the flow velocity increasing, and the temperature of the probe increases with the flow velocity decreasing. At the same flow rate and water content between 0% and 100%, the higher the water content, the lower the temperature of the speed-measuring probe, and the smaller the water content, the higher the temperature of the speed-measuring probe. The simulation results show that thermal flowmeter can be competent for flow detection of low production fluid and low flow well, which provides the basis for the detection method of low production fluid in the future and lays the foundation for the design of thermal flowmeter.

Improved hydrogen consumption detection method with flow meter of fuel cell vehicle

With the vigorous development of fuel cell vehicles, the hydrogen consumption in the driving process of fuel cell vehicles has become a major concern of automobile manufacturers and fuel suppliers. However, the measurement accuracy of flow meter in hydrogen medium cannot meet the requirements. In this paper, computational fluid dynamics software is used to simulate the velocity distribution of water and hydrogen in Coriolis flow meter with different mass flow rates without tube vibration. Aiming at the measurement error of Coriolis flow meter, a flow calibration device based on sonic nozzle was designed, and the results of measuring hydrogen mass flow by Coriolis flow meter and thermal flow meter were calibrated. Finally, the accuracy of the calibrated flow meter for measuring hydrogen mass flow under stable and dynamic conditions is tested. The test results show that the accuracy of calibrated Coriolis flow meter for hydrogen mass flow is less than ±1%, which can meet the accuracy requirements of fuel cell vehicle hydrogen consumption measurement. This study provides an important reference for the application of flow meter method in fuel cell vehicle economic evaluation method.

Beam induced heat load instrumentation installed in LHC during the Long Shutdown 2

During the second run of the Large Hadron Collider (LHC) between 2015 and 2018, significant beam induced heat loads have been observed on the beam screens circuits impacting the cryogenic system capacity, mainly due to the electron clouds generated by the beams. To validate these measurements and to obtain precise heat load assessments and comparison with preliminary calculations based on existing hardware equipment at selected locations, it was decided to add new cryogenic instrumentation around the machine. In total, 23 Coriolis flowmeters (cold conditions), 4 thermal flowmeters (room temperature conditions) and 58 Cernox thermometers have been installed and commissioned between 2019 and 2021 during the so-called long shutdown 2 (LS2). This paper presents an overview of this project, including the commissioning of these instruments and confirming at first stage the original heat load estimations.

Microfluidic Thermal Flowmeters for Drug Injection Monitoring

This paper presents a microfluidic thermal flowmeter for monitoring injection pumps, which is essential to ensure proper patient treatment and reduce medication errors that can lead to severe injury or death. The standard gravimetric method for flow-rate monitoring requires a great deal of preparation and laboratory equipment and is impractical in clinics. Therefore, an alternative to the standard method suitable for remote, small-scale, and frequent infusion-pump monitoring is in great demand. Here, we propose a miniaturized thermal flowmeter consisting of a silicon substrate, a platinum heater layer on a silicon dioxide thin-membrane, and a polymer microchannel to provide accurate flow-rate measurement. The present thermal flowmeter is fabricated by the micromachining and micromolding process and exhibits sensitivity, linearity, and uncertainty of 0.722 mW/(g/h), 98.7%, and (2.36 ± 0.80)%, respectively, in the flow-rate range of 0.5–2.5 g/h when the flowmeter is operated in the constant temperature mode with the channel width of 0.5 mm. The measurement range of flow rate can be easily adjusted by changing the cross-sectional microchannel dimension. The present miniaturized thermal flowmeter shows a high potential for infusion-pump calibration in clinical settings.

Optimization of a Thermal Flow Meter for Failure Management of the Shunt in Pediatric Hydrocephalus Patients.

Hydrocephalus patients suffer from an abnormal buildup of cerebrospinal fluid (CSF) in their ventricles, and there is currently no known way to cure hydrocephalus. The most prevalent treatment for managing hydrocephalus is to implant a ventriculoperitoneal shunt, which diverts excess CSF out of the brain. However, shunts are prone to failure, resulting in vague symptoms. Our patient survey results found that the lack of specificity of symptoms complicates the management of hydrocephalus in the pediatric population. The consequences include persistent mental burden on caretakers and a significant amount of unnecessary utilization of emergency healthcare resources due to the false-positive judgement of shunt failure. In order to reliably monitor shunt failures for hydrocephalus patients and their caretakers, we propose an optimized design of the thermal flow meter for precise measurements of the CSF flow rate in the shunt. The design is an implantable device which slides onto the shunt and utilizes sinusoidal heating and temperature measurements to improve the signal-to-noise ratio of flow-rate measurements by orders of magnitude.Clinical Relevance- An implantable flow meter would be transformative to allow hydrocephalus patients to monitor their shunt function at home, resulting in reduced hospital visits, reduced exposure to radiation typically required to rule out shunt failure, and reduced caretaker anxiety.

Design, Simulation, and Fabrication of a Copper-Chrome-Based Glass Heater Integrated into a PMMA Microfluidic System.

In this paper, the development of a copper–chrome-based glass microheater and its integration into a Polymethylmethacrylate (PMMA) microfluidic system are presented. The process highlights the importance of an appropriate characterization, taking advantage of computer-simulated physical methods in the heat transfer process. The presented system architecture allows the integration for the development of a thermal flow sensor, in which the fluid flows through a 1 mm width × 1 mm length microchannel across a 5 mm width × 13 mm length heating surface. Using an electrothermal analysis, based on a simulation and design process, the surface heating behavior curve was analyzed to choose a heating reference point, primarily used to control the temperature point within the fluidic microsystem. The heater was characterized using the theory of electrical instrumentation, with a 7.22% error for the heating characterization and a 5.42% error for the power consumption, measured at 0.69 W at a temperature of 70 °C. Further tests, at a temperature of 115 °C, were used to observe the effects of the heat transfer through convection on the fluid and the heater surface for different flow rates, which can be used for the development of thermal flowmeters using the configuration presented in this work.

Period verification device for ventilation rate standard rods based on a digital thermal flowmeter

Period verification device for ventilation rate standard rods based on a digital thermal flowmeter

Flow Rate Measurement of Production Profile Logging Using Thermal Method

This paper presents a kind of thermal flow meter designed to measure downhole fluid flow at production profile logging. A computational fluid dynamics model is established to study the variation of temperature field in Downhole Thermal Flow Meter with medium and input power. The relation curve between heating power and fluid velocity and heating time is determined. According to the theoretical research, the experimental prototype of downhole thermal flow meter is designed and manufactured, and the dynamic experimental research is carried out on the multiphase flow simulation experimental device. The results show that when the power of the heating wire is constant, the temperature of the liquid around the heating wire decreases with the increase of the flow rate, and the resolution of the instrument is obvious when the flow rate is less than 20 m3/d. When the flow rate is constant, the greater the power of the heating wire, the more obvious the response characteristics of the instrument. It has a good response in the whole single-phase oil and single-phase water environment. The research of theoretical and dynamic experimental shows that it is feasible to use downhole thermal flow meter to measure downhole flow. This method will provide a new idea for the measurement of flow in production profile.

Simulation and Experimental Studies on the Influencing Factors of a Thermal Flowmeter with Constant Temperature Difference

Due to the fact that the thermal flowmeter with constant temperature difference brings large errors when measuring downhole flow in low flow-rate, the influence of temperature and pressure was studied. According to the relationship between the electric power of the flowmeter heater and the measured flow rate, the influence of temperature on the physical parameters of liquid water was analyzed, and the change curve of the heat transfer power of the flowmeter and flow rate at different temperatures was simulated numerically. An experimental platform with adjustable water temperature and flow rate was built on that basis, and the relationship between the power of the flowmeter and flow rate at 25–40 °C under constant pressure was thereby analyzed, revealing that power of the flowmeter heater increases monotonically with temperature. In terms of theoretical analysis, a 500 m increase in the well depth leads to an error of 2.2 m3/d when the flowmeter is in the depth from 0 to 2 000 m; while the error is 0.6 m3/d when it is in the depth from 2 000 to 4 000 m. The results showed that output power of the thermal flowmeter with constant temperature difference will increase with the increase of well depth (wellbore temperature, pressure change), resulting in measurement errors, which provides a theoretical basis for the correction and effective application of the flowmeter measurement results.

Thermal flow sensor used for thermal mass flowmeter

Actually, many devices used for flow rate measurement in oil and gas fiscal metering like orifice and turbine meters are often employed. This work deals with dispersion thermal flow meter fabricated by hot wire anemometers technology using the thermal domain for measuring natural gas in transaction operations, where it is unusually used.The choice of this type of flow meters comes from the fact that the authors observed an abnormality in the production field in the south of Algeria. Which consists of the total flow rate of different wells is extensively different from the amount recovered in the storage bin especially in the summer season. We are sure that the use of this kind of device will help us to understand this irregularity.The main objective of our work is to study the essential component of the thermal mass flow meter “thermal anemometer”, and to simulate this one with the parameters of Algerian gas field in order to have the ability to compare the results obtained with the field data.Attention is paid to the sensors’ geometry. Thermal anemometer flows sensor may comprise a heater and several temperature sensors. They convert the flow energy overheat transfer into electrical signals.