A3.3 - Novel Sensor Geometry for Liquids Serving in Dispersion Thermal Flow Meters

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings SENSOR 2011
A3 - Flow Measurement
A. Badarlis, A. Kalfas - Aristotle University of Thessaloniki (Greece), V. Kumar, A. Pfau - Endress+Hauser Flowtec AG, Reinach (Switzerland)
78 - 83


Dispersion thermal flow meters in industrial application in liquids are not common and can not operate in high flow velocities. The main problem which prohibits the use of thermal flow meters in high flows is the fact that the the characteristic curve of the flow meter becomes less sensitive in high flow rates. In addition, the ratio of measurement signal to the noise decreases and the electronics are not capable to detect small changes of the signal.
In the flow sensor under investigation a sensor element is used which consists of a round heating area and a concentric ring around it to measure temperature, this offers additional information about the sensor which can be used for an alternative approach on the measurement quantity. The advantages of this approach are two. Firstly, the influence of the sensor components in the measurement quantity is reducing. This happens due to the fact that the measured temperature at the ring position represents the surface temperature of the cap. In addition, there is no need for simultaneously temperature measurement on the heater. In the first part, the problem was approached with analytical equations investigating the dependency of the measurement quantity from its parameters. The main part of the investigation was related to numerical calculation of a 3D CFD model, based on the standard and the proposed approaches. The finite volume method in conjugated heat transfer problem was used, allowing the coupled heat transfer solution of fluid and solid domain.
From the numerical calculation results is concluded that the proposed model improves the gradient of the characteristic curve, in high flow rates, by 41.8%.