Development And Design Of A High Accuracy Large Caliber Ultrasonic Heat Meter

In recent years,with the continuous implementation of the national energy conservation and emission reduction policy,the long-term thermal waste phenomenon in China's heating system has been significantly improved.However,the heating system in the northern part of China still has different degrees of heat waste,which not only wastes the coal resources but also pollutes the environment.The main reason is that the thermal measurement technology is not mature enough.At present,the heat meter of small caliber households in the market developed more mature.However,the large caliber multichannel ultrasonic heat meter has the problem of large error of flow measurement especially the low precision of small flow point and large error fluctuation.Accordingly it's important to research the high caliber and the ultrasonic heat scale.In view of the above problems,this thesis designed a DN200 caliber four-channel ultrasonic heat meter.The flow measurement principle based on time difference method is adopted.Firstly,the time-difference measurement model is analyzed.The scheme of multichannel layout scheme is determined,and in principle,the flow integration error is reduced,and the anti-jamming ability of the ultrasonic heat meter for fluctuation of flow rate is improved.Second,the temperature of the inlet and outlet is measured by a paired temperature sensor.For the non-linear influence of the temperature change on the accuracy of the flow measurement,the least squares surface fitting temperature compensation algorithm is used for compensation,the validity of the temperature compensation is proved by MATLAB software simulation,and the measurement error is reduced.Finally,the heat released through the heat exchange system is calculated by the integrator.The hardware system of ultrasonic heat meter based on MSP430F449 microcontroller is designed.And the flow measurement circuit.temperature measurement circuit,communication circuit and key circuit are designed through the high-precision time measurement chip UTA6903The ultrasonic heat meter designed in this thesis,with the intern company platform completed the ultrasonic flow sensor parameter matching and sending and receiving waveform test,flow accuracy test,temperature test,anti-jamming test and power consumption test.The test results exceed the national requirements for flow metering two-level meters,they have low power consumption and have certain value of engineering use.