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.

Novel Air Flow Meter for an Automobile Engine Using a Si Sensor with Porous Si Thermal Isolation

Abstract: An air flow meter for measuring the intake air of an automobile engine is presented. It is based on a miniaturized silicon thermal mass flow sensor using a thick porous Si (Po-Si) layer for local thermal isolation from the Si substrate, on which the sensor active elements are integrated. The sensor is mounted on one side of a printed circuit board (PCB), on the other side of which the readout and control electronics of the meter are mounted. The PCB is fixed on a housing containing a semi-cylindrical flow tube, in the middle of which the sensor is situated. An important advantage of the present air flow meter is that it detects with equal sensitivity both forward and reverse flows. Two prototypes were fabricated, a laboratory prototype for flow calibration using mass flow controllers and a final demonstrator with the housing mounted in an automobile engine inlet tube. The final demonstrator was tested in real life conditions in the engine inlet tube of a truck. It shows an almost linear response in a large flow range between –6,500 kg/h and +6,500 kg/h, which is an order of magnitude larger than the ones usually encountered in an automobile engine.

MEMS thermal flow sensor with compensation for fluid composition

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.

Deployable mandrel for downhole measurements

Abstract: The disclosed apparatus comprises a phase fraction meter and a compliant mandrel deployable within a production pipe, and may further comprise a flow velocity meter. The mandrel allows the determination of the phase fraction for a fluid comprising three phases by providing an additional cross sectional compliance within the conduit, thereby allowing the density of the fluid to be determined. The mandrel also provides a specified blockage through the flow velocity meter, thereby increasing flow velocity through the meter. This allows flow rate measurements in conditions under which flow velocity in the under-restricted cross-sectional area of the pipe would normally be very low. Further, the mandrel can provide a specified restriction in the pipe, i.e., a venturi. By measuring the differential pressure across the venturi and utilizing the measured fluid velocity from the flow velocity meter, the density of the fluid mixture can be calculated. This calculated density can be used in conjunction with other measurements to determine phase fractions or to double check or to calibrate the phase fraction meter. The mandrel can be deployed without removing the meter from the conduit, allowing for easy adaptation to changing flow parameters and fluid compositions.

Volume flow meter that measures transit time

Abstract: An aerodynamic enclosure is placed in the flow, the enclosure including an opening enabling the enclosure to be filled with the flowing fluid, and having a thermal pulse generator mounted flush with its wall, which generator is suitable for emitting modulated thermal pulses simultaneously to the outside and to the inside of the enclosure. A first thermal sensor is located in the flow and a second thermal sensor is located in the enclosure. The sensors measure propagation times or phase shifts of the thermal waves respectively in the flow and in the non-flowing fluid, thereby making it possible to deduce the value of the fluid flow rate while compensating for any variations in the temperature, pressure, and composition of the fluid. The invention is applicable to gas metering.