Thermal dissipation type mass flowmeter and method for measuring mass flux

Abstract

The invention discloses a heat dissipation mass flow meter and a mass flow measuring method. The flow meter comprises a flow measuring RTD and a temperature measuring RTD, a resistance measuring module used for measuring the resistances of the flow measuring RTD and the temperature measuring RTD, a microprocessor used for obtaining the temperatures of the flow measuring RTD and the temperature measuring RTD according to the resistances, calculating the temperature difference between the flow measuring RTD and the temperature measuring RTD and sending out digital signals to a digital-to-analogue converter, controlling the heating power to the flow measuring RTD through the digital-to-analogue converter, a pressing control voltage / current supply and also determining the present flowing speed of the liquid according to the temperature difference or heating power, the digital-to-analogue converter used for carrying out digital-to-analogue conversion on the digital signals and sending out control voltage to the pressing control voltage / current supply and the pressing control voltage / current supply used for sending out voltage / current to the flow measuring RTD according to the control voltage so as to heat the flow measuring RTD. The invention realizes accurate control to the temperature difference and heating power, thus enhancing the accuracy of flow measuring.

Description

technical field [0001] The invention relates to the field of fluid flow measurement, in particular to a heat dissipation mass flowmeter and a mass flow measurement method. Background technique [0002] Where there is material flow, people need to measure the flow in order to grasp the quantity. Flow is divided into instantaneous flow (Flow Rate) and cumulative flow (Total Flow). The amount that passes through the effective section of a closed pipe or open channel per unit time is called instantaneous flow, and the cumulative amount that flows through the effective section of a closed pipe or open channel within a certain period of time is called cumulative flow. The cumulative flow can be obtained by integrating the instantaneous flow with respect to time. flow. [0003] Instruments used to measure instantaneous flow or cumulative flow are collectively referred to as flowmeters. A mass flow meter (Mass Flow Meter, MFM) is an instrument that accurately measures fluid flow....

AI Technical Summary

Problems solved by technology

However, since the resistance value R of the current measuring RTD changes with the temperature, the heating power calculation formula P=U 2 / R or P=I 2 It can be seen from R that this method cannot achieve accurate constant heating power

[0022] (3) Whether it is power measurement method or temperature difference measurement method, the existing technology is realized by using analog circuit design technology, and the circuits of the two are difficult to integrate into a set of circuits, so it is difficult to realize the integration of power measurement method and temperature difference measurement method. in the measurement system

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