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Thermal mass flow meter

About: Thermal mass flow meter is a research topic. Over the lifetime, 1759 publications have been published within this topic receiving 21878 citations.


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Journal ArticleDOI
TL;DR: To calculate the pump flow rate indirectly from measuring the flow rate of the driving air of the VAD air chamber, experiments using a mock circuit were conducted to investigate the correlation between the air flow rate and the pumpflow rate as well as its accuracy and error factors.
Abstract: Our research institute has been working on the development of a compact wearable drive unit for an extracorporeal ventricular assist device (VAD) with a pneumatically driven pump. A method for checking the pump blood flow on the side of the drive unit without modifying the existing blood pump and impairing the portability of it will be useful. In this study, to calculate the pump flow rate indirectly from measuring the flow rate of the driving air of the VAD air chamber, we conducted experiments using a mock circuit to investigate the correlation between the air flow rate and the pump flow rate as well as its accuracy and error factors. The pump flow rate was measured using an ultrasonic flow meter at the inflow and outflow tube, and the air flow was measured using a thermal mass flow meter at the driveline. Similarity in the instantaneous waveform was confirmed between the air flow rate in the driveline and the pump flow rate. Some limitations of this technique were indicated by consideration of the error factors. A significant correlation was found between the average pump flow rate in the ejecting direction and the average air flow rate in the ejecting direction (R2 = 0.704-0.856), and the air flow rate in the filling direction (R2 = 0.947-0.971). It was demonstrated that the average pump flow rate was estimated exactly in a wide range of drive conditions using the air flow of the filling phase.

6 citations

01 Jan 2006
TL;DR: In this paper, the authors describe the use of a digital drive and an agile control system to maintain flow tube oscillation through two-phase flow or batching to or from an empty flow-tube.
Abstract: Coriolis mass flow metering has been established as the most accurate widely-used industrial flow measurement technology since its introduction in the mid 1980s. Coriolis meters operate (Fig. 1) by oscillating a flow-tube (typically 1-300 mm in diameter), at the natural frequency of a selected mode of vibration, the so-called drive mode. Two sensors monitor the flow-tube vibration as the process fluid passes through. The frequency of oscillation (in the range 50Hz - 1kHz depending on flow-tube geometry) is determined by the overall mass of the vibrating system, and hence for a given flow-tube, this varies with the density of the process fluid. Accurate determination of the frequency of vibration thus enables the process fluid density to be calculated. The geometry of the flow-tube is arranged so that Coriolis forces act to give a phase difference between the two sensor signals, roughly proportional to the mass flow of the process fluid (which in the largest meters may approach 1 tonne/s). While the flow-tube is essentially a mechanical device with a few electrical transducers (sensors and drivers), the transmitter is an electronic and computational device which drives and monitors the flow-tube, and which generates the measurement data. A long-term research programme at the University of Oxford has been developing all-digital transmitter technology [3, 4, 5] with various improvements including a very fast response time [6] and an ability to operate in two-phase flow [1-5]. The transmitter architecture in Fig. 1 includes audio quality analog-to-digital converters (ADCs) and digital-to-analog convertors (DACs), with 24-bit samples delivered at 48kHz. Field Programmable Gate Arrays (FPGAs) are chips consisting of configurable logic blocks, capable of carrying out complex digital algorithms in real time and in parallel. FPGA tasks include interfacing to the ADCs and DACs, generating the drive waveform and pre-filtering of the measurement data. This architecture is used in Invensys Foxboro’s commercial product, the CFT-50 Coriolis transmitter, which was used in the trials. Reizner [7] provides a good background to the problems associated with metering two-phase flow using Coriolis meters. In brief, it is difficult to maintain flow-tube oscillation in two-phase, as the condition induces very high and rapidly fluctuating damping (up to 3 orders of magnitude higher than for single phase conditions). When the transmitter is unable to maintain oscillation, the meter is described as “stalled”, and no (valid) measurement can be provided. Even where stalling is averted, large measurement errors may be induced into the mass flow and density measurements. Previous papers have described the use of a digital drive and an agile control system to maintain flow-tube oscillation through two-phase flow or batching to or from an empty flow-tube [2,8]. In this paper, it is assumed that the transmitter has this capability. The focus is restricted to

6 citations

Patent
20 Jul 2011
TL;DR: In this article, a flow meter system and a method are provided for accurately measuring the percentage amounts of liquid and gas phases in a multiphase flow through a conduit when the liquid phase constitutes a small minority portion (e.g., less than about 20%) of the multi-phase flow.
Abstract: Both a flow meter system and method are provided for accurately measuring the percentage amounts of liquid and gas phases in a multiphase flow through a conduit when the liquid phase constitutes a small minority portion (e.g., less than about 20%) of the multiphase flow. The system includes a flow meter that includes a differential pressure sensor connected across a Venturi in the conduit, and a dual energy fraction meter, each of which is operably connected to a digital processor. The system further includes a pump connected to the conduit upstream of the flow meter that introduces at least one pulse of a known quantity of liquid, the pulse being sufficient in volume to temporarily increase the liquid phase by a detectable amount. After the liquid pulse is introduced into the multiphase flow, the digital processor computes the changes in the percentage amounts of the liquid and gas phases which should have occurred as a result of the pulse, and compares the computed changes with the actual changes measured by the flow meter in order to calibrate the flow meter. The measured increase in the liquid flow is then subtracted from the total measured liquid flow to determine the actual percentage of liquid flow.

6 citations

Proceedings ArticleDOI
18 May 1998
TL;DR: In this paper, the design of an Intel 8085 microprocessor based flow rate and now volume indicator common for both Turbine flowmeters and vortex shedding flow meters is given.
Abstract: Design of an Intel 8085 Microprocessor based flow rate and now volume indicator common for both Turbine flowmeters and vortex shedding flow meters are given. The above indicator can be used not only for the above two types of now meters but also for any other flowmeter which gives pulse output. The flowmeter can be used in any medium (liquid or gas). The only required information for the design are the Maximum Flow Rate and the mean "Meter Factor" of the flow meters; the design is applicable for flowmeters of any size/diameter. The mean "Meter Factor" should be present at site using 4 thumb wheel switches before the operation of the meter. The maximum flowrate and mean "meter factor" values of the flowmeter are used to decide the setting of the 5th Thumb wheel switch which in turn decides one of the four set durations for which the pulses from the flow sensor are to be counted periodically for calculation of flow rate information. The microprocessor reads the settings of the 5 Thumb wheel switches and pulse counter contents and calculates the flow rate and flow volume and displays them in digital form. The paper gives the block diagram and the flow chart for the operation of the indicator.

6 citations

Patent
22 Aug 2002
TL;DR: In this paper, a gas meter that functions as both a mass flow meter and an energy meter is presented, having a gas quality sensor with means for determining a gas parameter that is indicative of whether the gas is combustible or not.
Abstract: Method for measuring gas consumption using a gas meter, especially for measuring gas energy consumption, whereby the meter is suitable for measuring both a gas mass flow and energy consumption in that the meter determines the gas type and if it is incombustible calculates a mass flow in weight or volume units, liters per minute (l/min), while if it is combustible calculates consumption in energy units, kWh. An independent claim is made for a gas meter that functions as both a mass flowmeter and an energy meter, having a gas quality sensor with means for determining a gas parameter that is indicative of whether the gas is combustible or not. To determine the gas type its heat conductivity, heat capacity, diffusivity or viscosity are calculated, from which the gas mixture can be determined.

6 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202312
202226
20212
20208
20194
201811