| 摘要 |
The invention relates to an apparatus for determining and/or monitoring mass flow of a fluid medium (3) through a pipeline (2), or through a measuring tube. The apparatus includes two temperature sensors (11, 12) and a control/evaluation unit (10). The two temperature sensors (11, 12) are arranged in a region of a housing (5) facing the medium (3) and in thermal contact with the medium (3) flowing through the pipeline (2), or through the measuring tube. A first of the temperature sensors (11) is heatably embodied. A second of the temperature sensors (12) provides information concerning the present temperature of the medium (3). The control/evaluation unit (10), on the basis of primary measured variables, such as temperature difference (&Dgr;T=T2−T1) between the two temperature sensors (11, 12) and/or heating power (P) fed to the first temperature sensor (11), ascertains the mass flow of the medium (3) through the pipeline (2). The control/evaluation unit (10), in ascertaining the mass flow, provides a correction value (K) for the mass flow and/or for the primary measured variable (&Dgr;T, P) and/or for a measured value derived from the primary measured variable (&Dgr;T, P). And, the control/evaluation unit (10), in ascertaining the correction value (K), takes into consideration heat exchange by forced convection and heat exchange by free convection between the temperature sensors (11, 12) and the medium (3).
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