Innovator Sensor Technology Ist Ag

Innovative Sensor Technology Ist Ag

Ralf Emanuel Bernhardsgrütter

Christoph Hepp

Bastian Engel

A method for operating a thermal sensor, wherein the thermal sensor includes a sensor element and an electronics, the sensor element in thermal contact with a container, in which a measured medium flows with a flow velocity, the sensor element periodically heated by an alternating voltage and, at the same time, a temperature of the sensor element is registered versus time, wherein the electronics determines a measured variable of the measured medium based on a comparison of the third harmonic oscillation of the alternating voltage with the third harmonic oscillation of the temperature, including calculating a phase shift between the third harmonic oscillation of the alternating voltage and the amplitude of the third harmonic oscillation of the temperature, and wherein a frequency of the alternating voltage is selected to achieve a penetration depth of an emitted heat of the sensor element into the measured medium at essentially zero flow velocity.

Thermal sensor and method for operating the thermal sensor

A method for operating a thermal flow sensor includes: bringing a measuring medium into thermal contact with a sensor element of the flow sensor and periodically heating the medium using an AC voltage introduced into the sensor element; simultaneously detecting a maximum amplitude of a temperature and/or a phase shift between a curve of the AC voltage and the curve of the temperature; adjusting the detected maximum amplitude and/or the detected phase shift using calibration data; determining an isoline using the adjusted maximum amplitude and/or the adjusted phase shift based on model of the flow sensor, wherein the isoline has a plurality of value pairs of thermal conductivity and thermal capacitance of the medium; deriving a medium information from the isoline; and performing a flow measurement by converting signal values from the sensor element into measurement values of an effective flow velocity of the medium using the medium information.

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Sulgen, Switzerland

Ralf Emanuel Bernhardsgrütter