Study On The Measurement Of Gas Thermal Dissipation Method Based On Micro Flow Method

In this paper, the basic principle of the law of heat conduction based on the design of constant temperature difference type thermal gas mass flowmeter. The volume of the traditional instrument using easily affected by environmental factors, and the measurement of small flow can not accurately measure the impact flow meter measurement accuracy, serious. This research is mainly aimed at small flow measurement of gas quality has developed a new type of thermal mass flow meters. Thermal mass flowmeter is a heat transfer principle of the detecting instrument based on mass flow, according to the heat between the fluid and the heat flow in the relationship of direct measurement of mass flow meter. This paper also describes in detail the design process of the heat flow meter.The CTD flow meter’s(Constant temperature differential thermal gas mass flow meter) flow sensor using platinum resistance Pt20 and Pt100 as measuring element, made the temperature of the heating resistor Pt20 constant higher 80℃ than the temperature resistance Pt100’s temperature. According to the characteristics of the flow sensor, measurement and control circuit of the hardware design of thermal mass flowmeter. According to the industrial instruments to measure mass flow requirements, try to simplify the hardware circuit design, selection of good quality and high performance price ratio of the components, reducing the overall error of the system, to ensure the system stability and accuracy.Thermal mass flow meter designed in this subject is based on C8051F410 single chip microcomputer. Design of communication protocol between the main control computer software and flow meter and the computer, according to set a good medium, pipe diameter, according to the actual need, the system measurement accuracy of real-time data transmission to the computer, realize the data exchange and transmission. Then the experimental results are processed by the host computer software.Finally, thermal mass flowmeter will be completed after the standard flow generating device, to determine the relationship between the thermal gas mass flow meter of the mass flow rate and the output voltage signal. In order to obtain the precise traffic data and better meet the requirements of industrial measurement, through the curve fitting algorithm, the instantaneous flow rate formula and the formula as the large system, obtain the data of measured gas flow. Flow meter and computer gas mass heat are connected through the RS-485 communication interface, the computer and the thermal gas mass flow meter, communication, and various parameters can be set and read, to ensure the measurement accuracy of flow meter. The measurement range of thermal mass flowmeter can be set in accordance with the requirements of 4mA to 20 mA, the output current in the full scale range, accurate control of flow.