Showing papers on "Thermal mass flow meter published in 2011"

Response time of thermal flow sensors with air as fluid

Abstract: Due to their fast response time miniaturized thermal flow sensors can be applied well for the measurement of instationary gas flow. For some applications, the response time of the sensor must be known with high accuracy. We investigated three methods for response time determination with air: a jump of temperature induced by electric heating, a gas velocity step made by a membrane burst and acoustic phase shifts between sound velocity and sound pressure (standing and traveling waves). The measurements have shown that the response time of thermal flow sensors is a function of flow velocity. For stagnant flow, the thermal response time is about 4.5 ms for our thermal flow sensors. With increasing flow from the heater to the thermopiles, the heat transfer rises. Thus, the response time is faster and decreases to about 1 ms.

Micro-hydraulic structure for high performance bio-mimetic air flow sensor arrays

Abstract: Here we introduce a novel micro-hydraulic structure that can significantly improve performance of many MEMS devices. Using this structure we fabricate and test a new type of low-power, accurate and robust flow sensor in which a hair-like appendage is used to translate flow into hydraulic pressure. This pressure is hydraulically amplified and sensed with a capacitance that is integrated with the micro-hydraulic system. The air flow sensor can detect flow speeds ranging from zero to 10 m.s−1 with a resolution of 1 cm.s−1 in the low flow regime and a predicted minimum detectable flow of 3 mm.s−1.

Flow rate meter

Abstract: The present invention is flow rate meters which are able to accurately measure the volumetric rate of flow of a liquid through a conduit without requiring foreknowledge of the physicochemical characteristics of the liquid, e.g., for the purpose of calibration of the thermal mass flow rate. One application of the flow meters of the invention is to incorporate them in a system for measuring the flow rate of urine excreted by a catheterized patient. The invention also provides methods for using the flow rate meters.

Air mass flow meter

Abstract: An air mass flow meter, includes a housing made of plastic having an electrically insulating effect. A flow channel is formed in the housing. The air mass flow motion also includes a sensor element which is arranged in the housing and detects the air mass flowing in the flow channel. Conductive paths are arranged in the housing and connect the sensor element to connection pins. In order to provide a mass air flow meter which is cost-effective to produce and allows precise measurement of a mass air flow, the entire housing is made of plastic and at least one part of the flow channel has electrostatically dissipative properties.

Thermal fluid flow apparatus

Abstract: Provided is a compact apparatus for measuring the flow rate of a fluid. The apparatus includes a heated measure element and a heated reference element which are in substantially the same thermal environment within a measure cell, except that the measure element is situated in the path of the cooling fluid flow and the reference element is sheltered from this direct fluid flow. These elements are arranged as parallel and concentric planar elements that are essentially identical to each other with matching thermal characteristics. The elements are electrically connected in a Wheatstone bridge arrangement. Thermal exchange between the reference and measure elements is used to optimise noise rejection due to common mode background thermal effects. Measured parameters from the bridge can be used to derive the fluid flow rate.

Means and method for monitoring the flow of fluid

Abstract: The invention relates to an means and method for monitoring the flow of a fluid. The invention relates to an electromagnetic flow meter and method for measuring the axial velocity profile of a conducting fluid. The conducting fluid may be a conducting single phase fluid or a conducting continuous phase of a multiphase fluid. The conducting fluid may have a uniform flow profile or a non-uniform flow profile. The electromagnetic flow meter and method measure the axial velocity profile of a conducting fluid by dividing the flow cross section into multiple pixels and determining the axial velocity of the conducting fluid in each pixel. Having. derived the axial velocity profile, the electromagnetic flow meter and method may further derive the volumetric flow rate of the conducting fluid. The electromagnetic flow meter and method may be suitable for measuring the axial velocity profile and optionally the volumetric flow rates of each phase of a multiphase fluid.

Method and apparatus for determining differential flow characteristics of a multiple meter fluid flow system

Abstract: A fluid flow system (300) is provided. The fluid flow system (300) includes a pipeline (302) with a flowing fluid. The fluid flow system (300) further includes a first vibrating meter (5) including a first sensor assembly (10) located within the pipeline (302) and configured to determine one or more flow characteristics, including a first flow rate. A second vibrating meter (5') including a second sensor assembly (10') located within the pipeline (302) is provided that is in fluid communication with the first sensor assembly (10) and configured to determine one or more flow characteristics, including a second flow rate. The fluid flow system (300) further includes a system controller (310) in electrical communication with the first and second vibrating meters (5, 5'). The system controller (310) is configured to receive the first and second flow rates and determine a differential flow rate based on the first and second flow rates. The system controller (310) is further configured to compare the differential flow rate to a threshold value or band and correct one or more flow characteristics if the differential flow rate is less than a threshold value or band.

Minimally intrusive monitoring of a multiphase process flow using a tracer

Abstract: An apparatus for and a method of monitoring multiphase fluid flow passing within a pipe is provided. The method includes the steps of: a) providing a flow pressure value and a flow temperature value for the multiphase fluid flow within the pipe; b) sensing the fluid flow with a fluid flow meter operable to be attached to an exterior of the pipe, the flowmeter including a spatial array of at least two sensors disposed at different axial positions along the pipe, and producing flow velocity signals indicative of a velocity of the fluid flow traveling within the pipe; c) selectively injecting at least one tracer into the fluid flow passing within the pipe, at a known injection flow rate and concentration; d) sensing a sample of the fluid flow for the tracer, and producing tracer concentration signals indicative of the concentration of the tracer in the fluid flow; and e) determining one or more of a gas component flow rate, an oil component flow rate, and a water component flow rate, using one or more of the flow pressure value, the flow temperature value, the flow velocity signals, and the tracer concentration signals.

Espresso Machine Method and Apparatus

Abstract: A method and apparatus for measuring a resultant flow delivered by a pump coupled to an over pressure valve, the method comprising the steps of: measuring, using a first flow meter, feed flow to the pump; measuring, using a second flow meter, return flow from the over pressure valve; and calculating resultant flow, at least in part, by subtracting measured return flow from measured feed flow. A pump power modification module can further modifying the pump output pressure to enable pressure profiling.

A comparative study of flow rate characteristics of an averaging Pitot tube type flow meter according to H parameters based on two kinds of differential pressure measured at the flow meter with varying air temperature

Abstract: A new averaging Pitot tube flow meter that has a shape similar to an Annubar® type flow meter was designed and its flow rate characteristic was evaluated. The air temperature supplied to the developed flow meter was maintained at a constant by controlling electric power supply to an electric heater during the calibration. Two kinds of differential pressure measured at the flow meter were used in calculating the H parameters, which represent characteristics of the developed flow meter. One H parameter (HΔP1) which was newly proposed in this research was calculated based on the difference between upstream pressure (stagnation pressure) at the flow meter and static pressure of the measured flow. The differential pressure is equivalent to the dynamic pressure of the flow. The other H parameter (HΔP2) which is used in a typical Annubar® type flow meter was calculated based on the difference between upstream and downstream pressure at the developed flow meters. Relationship curves between the two H parameters and the mass flow rate at the developed flow meter were obtained. The curves based on the HΔP2 parameter, which uses the difference between up and down stream pressure, show different gradients for varying the controlled air temperature. However, the other curve, based on the other HΔP1 parameter, which uses the dynamic pressure, can be represented by one linear curve even with varying air temperature.

Diagnostic flow metering using ultrasound tomography

Abstract: For an accurate flow metering without considering the influences of flow control devices such as valves and elbows in closed conduits, velocity distribution in the cross-sectional area must be integrated. However, most flow meters, including multi-path ultrasonic, electromagnetic or Coriolis mass flow meters, require assumptions on the fully-developed turbulent flows to calculate flow rates from physical quantities of their own concern. Therefore, a long straight pipe has been a necessary element for accurate flow metering because the straight pipe can reduce flow disturbances caused by flow control devices. To reduce costs due to the installation of long straight pipes, another flow metering technique is required. For example, flow rates can be estimated by integrating velocity distributions in the crosssection of conduits. In the present study, ultrasound tomography was used to find the velocity distribution in the cross-section of a closed conduit where flow was disturbed by a Coriolis mass flow meter or a butterfly valve. A commercial multi-path ultrasonic flow meter was installed in the pipeline to measure the line-averaged velocity distribution in the pipe flow. The ultrasonic flow meter was rotated 180° at intervals of 10° to construct line-averaged velocity distributions in Radon space. Flow images were reconstructed by using a backprojection algorithm (inverse Radon transform). Flow diagnostic parameters were defined by calculating statistical moments, i.e., average, standard deviation, skewness, and kurtosis, based on the normalized velocity distribution. The flow diagnostic parameters were applied to flow images to find whether the parameters could discern flow disturbances in the reconstructed velocity distribution.

Multiphase Flow Meter

Abstract: A multiphase meter for a hydrocarbon-containing flow is provided to estimate the relative amounts of water, oil, and gas in the flow without separating the gas and liquid phases of the flow. The meter comprises a chamber for receiving and directing a flow vertically upward. A first capacitor assembly measures the capacitance about a central flow region of the chamber. A second capacitor assembly measures the capacitance about a peripheral flow region. The meter estimates the water content as a function of the peripheral capacitance and the gas content as a function of the arithmetic difference between the peripheral and central capacitance.

Designing low gas flow meters based on the calometric principle of flow rate measuring

Abstract: The current assortment of sensing devices for measuring rate of fluid flow covers a wide range of requirements related to normal operation conditions. In the area of the low and very low fluid flow devices the offered assortment is being diminished sharply. Availability of the devices is very limited and costly. The aim of the article is to design a methodology for constructing a sensor for measuring the low liquid flows and the experimental verification of design. The gas flow meter is based on the calometric measurement principle so that the flow rate it assessed taking into account the known transferred amount of heat to the fluid flow and the temperature differences of the medium before and after electric coil of Thomas cylinder determined by thermocouples.

Flow Meter With Improved Thermal Stability And Methods Of Use

Abstract: Devices and methods for controlling flow to a processing chamber are disclosed. The devices comprise a flow meter, an inlet tube in fluid communication with the flow meter, an outlet tube in fluid communication with the outlet of the flow meter, and thermal insulation encompassing at least a portion of the flow meter, at least a portion of the inlet tube and at least a portion of the outlet tube.

Fresh air flow estimation

Abstract: An apparatus includes an operating conditions module that interprets a number of compressor operating parameters; a compressor flow module that determines a compressor inlet flow in response to the number of compressor operating parameters; and a fresh air flow module that provides a fresh air flow value in response to the compressor inlet flow. The operating conditions module further interprets a current mass air flow value, and the apparatus further includes a mass air flow sensor trimming module that adjusts a mass air flow sensor drift value in response to the current mass air flow value and the fresh air flow value. The apparatus includes a diagnostics module that determines a mass air flow sensor is failed in response to the current mass air flow value and the fresh air flow value.

MEMS time-of-flight thermal mass flow meter

Abstract: An apparatus comprising a micromachined (a.k.a. MEMS, Micro Electro Mechanical Systems) silicon flow sensor, a flow channel package, and a driving circuitry, which operates in a working principle of thermal time-of-flight (TOF) to measure gas or liquid flow speed, is disclosed in the present invention. The micromachining technique for fabricating this MEMS time-of-flight silicon thermal flow sensor can greatly reduce the sensor fabrication cost by batch production. This microfabrication process for silicon time-of-flight thermal flow sensors provides merits of small feature size, low power consumption, and high accuracy compared to conventional manufacturing methods. Thermal time-of-flight technology in principle can provide accurate flow speed measurements for gases regardless of its gas compositions. In addition, the present invention further discloses the package design and driving circuitry which is utilized by the correlated working principle.

Flow meter system and method for measuring an amount of liquid in a largely gaseous multiphase 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.

Flow cell for a flow meter

Abstract: A flow cell that includes a sensor body with internal cable channels for routing cables from the sensor ports to communicate with a flow meter is disclosed.

Characteristics of Critical Nozzle Flow Meter for Measuring High-Pressure Hydrogen Gas

Abstract: The critical nozzle flow meter was developed for high-pressure hydrogen gas flow measurements, and its characteristics was experimentally examined with hydrogen gas at the pressure up to 70 MPa. The results show that the critical back pressure ratio is 0.93-0.95 under the above pressure conditions, and its discharge coefficient has a curious behavior which the discharge coefficient decreases with increasing the Reynolds number over 40 MPa. Also, tests filling hydrogen gas into the storage tank of fuel cell vehicle was conducted under 35 MPa condition with the developed flow meter, and the high efficiency of this flow meter was confirmed even on practical uses.

Understanding the Compatibility of Thermal Mass Flow Meter with Various Process Gases

Abstract: A majority of vacuum processes use the Thermal Mass Flow Meter (TMFM) as metering device for process gas. The purpose of this paper is to establish cross compatibility relationship of the TMFM with different process gases. This paper uses a compressible Computational Fluid Dynamic (CFD) solver to understand the behavior of TMFM with different process gases. The change in the characteristic curve at lower pressures has also been studied. Empirical correlations have been developed so that the change in characteristic curve of TMFM can be predicted accurately for different gases based on their physical properties.