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MEMS thermal flow sensor with compensation for fluid composition

TLDR
In this article, the authors present a method for measuring fluid flow rate of fluids of differing properties without necessity of a separate flow calibration for each fluid, without need for calibration of the flow sensor for that particular fluid.
Abstract
The present invention provides a MEMS thermal flow sensor or meter for measuring the flow rate of a fluid without need for calibration of the flow sensor for that particular fluid. A response curve is determined by plotting the sensor output voltage against the volume flow rate divided by fluid thermal diffusivity for a calibration fluid of known thermal diffusivity, and storing response curve data in memory. A conversion factor is employed to provide a measure of correct flow rate of an unknown fluid. This conversion factor is derived from the ratio of the thermal time constant of the calibration fluid to the thermal time constant of the measured fluid, the time constants being measured at zero flow. These time constants are stored in memory. This conversion factor in conjunction with the response curve data is utilized by the processor to produce the correct flow rate. The invention also encompasses a method for measuring fluid flow rate of fluids of differing properties without necessity of a separate flow calibration for each fluid.

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Citations
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Patent

Flow detection device

Samuel Bailey
TL;DR: A flow detector for detecting flow rates of fluid in pipes by measuring the temperature of the pipe and the ambient temperature and determining from the signals whether there is a flow in the pipe, by the shape of the temperature signals without providing any heat input to the pipe or fluid as discussed by the authors.
Patent

Fluid flow detection apparatus

Bailey Samuel, +1 more
TL;DR: In this article, the authors present a method for detecting a water leak in a pipe system of a building by estimating a temperature profile of water entering the pipe, based on identifying at least one temperature difference maximum of a second monitoring period, wherein each said difference maxima is a maximum temperature difference between ambient and pipe temperatures of a received sample.
Patent

Water flow analysis

Stephen Tooms, +1 more
TL;DR: In this paper, the temperature of a part of a water supply system between a water main (110) and the site is recorded as a function of time and analysed to determine a property indicative of the water consumption at the site.
Patent

Mass air flow sensor with absolute pressure compensation

TL;DR: In this article, a mass flow sensor assembly that contains an absolute pressure sensor for compensating via electronics an output reading of mass flow of a fluid through a channel is presented, where the flow and pressure sensors may be built in close proximity to each other in the channel.
Patent

Online calibration method and system of permanent magnetic type sodium flowmeter of embedded vortex generator

TL;DR: In this paper, an online calibration method and system of a permanent magnetic type sodium flowmeter of an embedded vortex generator is presented, which consists of the following steps: correcting a graduation characteristic relationship of a flowmeter according to a specific working condition of the permanent magnetic types sodium flow meter of the embedded vortex generators in the liquid metal sodium measurement.
References
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Patent

Method and apparatus for detecting and controlling mass flow

TL;DR: In this article, an empirically derived conversion function was derived by correlating the output signals of a mass flow instrument sensing the flow of a calibration fluid with the output signal of the mass flow instruments sensing the fluid flow of the process fluid.
Patent

Method and apparatus for measuring the density of fluids

TL;DR: The specific gravity, l, of a fluid of interest is determined based on thermal conductivity, k, and specific heat, cp, of the fluid in an embodiment using proximately positioned resistive heater and thermal sensor elements coupled by the fluid.
Patent

Flow sensor signal conversion

TL;DR: In this paper, a method of obtaining at least one representation of a characteristic function of a sensor from a test fluid during calibration of the sensor according to a sensor model has been proposed.
Patent

Flowmeter fluid composition correction

TL;DR: In this paper, the thermal conductivity, specific heat and density of the fluid measured can be used to correct a mass flowmeter measurement with respect to changes in composition of fluid.
Patent

Method for in-line calibration verification of mass flow meters

TL;DR: In this article, an apparatus for verifying the calibration of a flow meter contains a flow sensor assembly which has a flow tube defining an axial fluid path through the assembly; an upstream temperature sensor in thermal contact with the flow tube, the two sensors being operationally connected to a means for producing an output in response to a temperature difference between the first and second sensors.
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