Topic
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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TL;DR: In this article, an enhanced flow sensor is developed at IMTEK to enable simultaneous fluid characterization and flow velocity measurement, which is necessary to measure flow rates accurately by thermal means in cases where fluid properties fluctuate in time.
11 citations
TL;DR: In this article, a neural network has been trained with the output data for the flow sensor and tested on its measurements, and the predicted values are close to the real ones which indicate the neural net model gives a good approximation for the calibration curve of the single wire thermal flow sensor under different operating temperatures.
Abstract: Thermal flow sensors with a wide dynamic range are widely applied in practical fluid flow measurements to yield local velocity information and also for volume flow-rate measurements. The importance of such flow sensors inspired the authors’ investigations into wide-velocity range thermal sensors and the outcome of this work is summarized in this paper. The present novel sensor is mechanically the same as the hot-wire anemometer, but it is excited by discrete, widely separated, square waves of electrical current rather than a continuous current. The nominal output of the new sensor is a function of the time constant of the heated wire and thus also of the velocity of flow. The time constant decreases as the flow velocity increases, while the heat transfer increases. In this paper, the results obtained suggest that our measurements for flow velocity and volume flow rate are in very good agreement with the theoretical results for the present thermal flow sensor. A neural network has been trained with the output data for the flow sensor and tested on our measurements. It was observed that the quality of the results depends on the number of hidden neurons. The predicted values are close to the real ones which indicate the neural net model gives a good approximation for the calibration curve of the single wire thermal flow sensor under different operating temperatures. The sensor described here was developed for slowly changing unidirectional flows, and uses one wire of 12.5 μm diameter. It is excited at 30 Hz frequency and its usable flow velocity range is 0.01–25 m/s. This yields an effective operating range and corresponds to a bandwidth of 1–2500.
11 citations
Patent•
11 Jan 2001
TL;DR: In this paper, a gas analyzer is used to adjust or throttle the gas flow stream for purposes of delivering the flow stream according to a preselected parameter, which is related to desired operating conditions for a combustion device including a boiler or an engine.
Abstract: An energy metering device (100) includes a volumetric flow meter or mass flow meter (102) in combination with a gas analyzer that provides telemetry regarding the constituents of a natural gas flow stream. An interpreter (112) analyzes this information and provides a real time output corresponding to the enthalpy of combustion for the gas stream. This output is used to adjust or throttle the gas flow stream for purposes of delivering the flow stream according to a preselected parameter, which is related to desired operating conditions for a combustion device including a boiler or an engine.
11 citations
TL;DR: In this paper, a transit-time flow meter, using periodic temperature fluctuations as tracers, has been developed for measuring liquid flow as small as 0.1 ml/min in microchannels.
Abstract: A transit‐time flow meter, using periodic temperature fluctuations as tracers, has been developed for measuring liquid flow as small as 0.1 ml/min in microchannels. By injecting square waves of heat into the liquid flow upstream with a tiny resistance wire heater, periodic temperature fluctuations are generated downstream. The fundamental frequency phase shift of the temperature signal with respect to the square wave is found to be a linear function of the reciprocal mean velocity of the fluid. The transit‐time principle enables the flow meter to have high accuracy, better than 0.2%, and good linearity. This flow meter will be used to measure and control the small liquid flow in microchannels in flow injection analysis.
11 citations
Patent•
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TL;DR: In this article, a reinforcing element is provided on a first housing half, protruding into the flow opening over a portion of the ceramic substrate and being glued to the substrate in the same manner as the second housing half.
Abstract: In flow rate meters with a ceramic substrate extending into a flow opening and having at least one temperature-dependent resistor film, there is the danger that excessive acceleration forces from a fall or from an impact will break the ceramic substrate. There is also the danger of destruction of the ceramic substrate from being unintentionally touched by an object or a finger. To increase the protection of the ceramic substrate against breakage, a reinforcing element is provided on a first housing half, protruding into the flow opening over a portion of the ceramic substrate and being glued to the ceramic substrate in the same manner as the first housing half. Protective ribs protrude from the housing halves into the flow opening in the direction of the ceramic substrate and prevent unintentional contact with the ceramic substract by objects or fingers. The flow rate meter is suitable for measuring the flow rate of the aspirated air in internal combustion engines.
11 citations