Energy Harvesting Technology-based Low-power Ultrasonic Heat Meter

Currently, as the development of the ultrasonic measurement technology and many advantages, ultrasonic heat meters is playing a more and more important role in household heat metering, becoming the trend of heat meters. However, due to technical imperfections, there are still many problems in the development of ultrasonic heat meters. For the current difficulties and problems in ultrasonic heat meter, focusing on the power supply for the ultrasonic heat meter, ultrasonic sensors installed on the pipeline issue, measuring accuracy, low power consumption and so on, designed a household type, low-power ultrasonic heat meter system based on energy collection.In order to solve the long-term supply problem, energy collection system was designed in this paper. Heat in the pipeline was changed into electricity through semiconductor thermal power generation chip; through the load characteristics experiments under different conditions, the capacity of power generation system was given under different temperature; analysed the problems of the thermal energy system applying in heat meter, and finally used battery power and thermal power generation system parallel-designed program to avoid the problems when the capacity of thermal power generation system is insufficient or temperature fluctuations and other effects,which solved the problem of long-term power supply on ultrasonic heat meter very well.Viewing the problem of the ultrasonic sensors installed on the pipe, this paper designed a straight-through pipe, making ultrasonic propagation direction and flow direction the same.This not only simplified the calculation, but also solved the problem of incident angle of ultrasonic sensors. And used the fluid analysis software Fluent to optimize the design by changing the pipe diameter and pipe angle,which made sensor installed and measurement conveniently and also reduced the pressure loss.A high-precision time measurement chip TDC-GP2 was used to solve the problem of transit-time measurement accuracy, and used the most popular low-power microcontrollers MSP430F149 as totalizer.The system also can be lower power operation by software settings, and used software design to address such problems as impurities or bubbles affecting the measurement accuracy in the pipes of heating system by studying the fluid signal.