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.

Ultrasonic flow meter including guide elements

Abstract: The measurement of volume flows or mass flows in the intake system of motor vehicle internal combustion engines plays a significant role in reducing pollutant emissions. Therefore, an ultrasonic flow meter for measuring a flow rate of a fluid flowing in a primary flow direction is described. The ultrasonic flow meter has at least two ultrasonic transducers, the ultrasonic transducers being capable of emitting and/or receiving ultrasonic waves at an angle α to the primary flow direction which is different from 90°. Furthermore, the ultrasonic flow meter has at least one guide element which is entirely or partially situated in the fluid. This guide element diverts at least one part of the flowing fluid in such a way that in the diversion, a velocity component is transferred to at least one part of the flowing fluid perpendicular to the primary flow direction. Guide vanes or displacers in particular are described as guide elements. In addition, turbulators may be provided on the guide elements, the turbulators generating a longitudinal fluid bed along the guide elements and thus causing the flow of the fluid to have a better contact with the guide elements when flowing around them. This reduces turbulences within the ultrasonic flow meter. Compared to the devices known from the related art, the ultrasonic flow meters described are distinguished by an improved signal-to-noise ratio and accordingly by a higher measuring precision.

Fluid flow conditioner

Abstract: A device and method for conditioning media flowing within a conduit enabling sensors placed within short straight run distances to measure media flow with improved accuracy employing a thermal flow instalment. A flow conditioner downstream of a media flow measuring transducer has walls that diverge in the flow direction to optimize readings of the media flow from the transducer.

Microparticle tracking velocimetry as a tool for microfluidic flow measurements

Abstract: The accurate measurement of flows in microfluidic channels is important for commercial and research applications. We compare the accuracy of flow measurement techniques over a wide range flows. Flow measurements made using holographic microparticle tracking velocimetry (µPTV) and a gravimetric flow standard over the range of 0.5–100 nL/s agree within 0.25%, well within the uncertainty of the two flow systems. Two commercial thermal flow sensors were used as the intermediaries (transfer standards) between the two flow measurement systems. The gravimetric flow standard was used to calibrate the thermal flow sensors by measuring the rate of change of the mass of liquid in a beaker on a micro-balance as it fills. The holographic µPTV flow measurements were made in a rectangular channel and the flow was seeded with 1 µm diameter polystyrene spheres. The volumetric flow was calculated using the Hagen–Pouiseille solution for a rectangular channel. The uncertainty of both flow measurement systems is given. For the gravimetric standard, relative uncertainty increased for decreasing flows due to surface tension forces between the pipette carrying the flow and the free surface of the liquid in the beaker. The uncertainty of the holographic µPTV measurements did not vary significantly over the measured flow range, and thus comparatively are especially useful at low flow velocities.

Wet gas metering using a differential pressure based flow meter with a sonar based flow meter

Abstract: A method and apparatus for measuring a parameter of a wet gas flow is provided, wherein the apparatus includes a differential pressure based flow meter configured to determine a first volumetric flow rate of the wet gas flow. Additionally, the apparatus includes a sonar based flow meter configured to determine a second volumetric flow rate of the wet gas flow. Furthermore, the apparatus includes a processing device communicated with at least one of the differential pressure base flow meter and the sonar based flow meter, wherein the processing device is configured to determine the parameter (e.g., wetness, volumetric gas flow rate, and volumetric liquid flow rate) of the wet gas flow using the first and second volumetric flow rates.