The Research And Development Of Ultrasonic Heat Meter

Energy Crisis is an important problem that now faces our country. To resolve the problem, we can find more new energy, or we also can do our best to economize the energy. Hot water is an important kind of energy, which is widely used in people's daily life. But for a long time ,heating by hot water is charged by area, not charged by how much people use in deed ,which results in vast waste of heat. To change the status quo, there need a revolution in heat charge .In 1997, the country required that heating must be charged by the quantity of heat that people use. So a kind of heat meter is needed. Now there are many kinds of heat meters and most of them are impeller heat meters. Although this kind of heat meter has low cost, it is not enough exact, is difficult to be maintained and not used for long time. In recent years, with the improvement of ultrasonic flow measurement technology, ultrasonic heat meter has developed gradually. The main merits of the heat meter is non-contact measurement, high accuracy, convenience of installation and maintenance.According to the basic theory of heat meter and flow measurement with ultrasonic time difference, a set of ultrasonic heat meter is developed on basis of absorbing and referring to the domestic and foreign advanced ultrasonic heat meter technology. Considering in the ultrasonic heat meter the most difficult is the flow measurement with ultrasonic, in addition, the limit of the time and ability, the main work in the design is as follows:1. The architecture of the ultrasonic calorimeter systemThe ultrasonic heat meter system includes 3 parts: the calculator, the temperature sensor, the flow sensor. The calculator calculates the heat with the theory of enthalpy difference. The temperature sensor uses PT1000 thermocouple. The flow sensor uses the system of ultrasonic flow measurement that is designed by the author.2. The hardware design of ultrasonic flow measurement systemAccording to the theory of time difference, around the single chip(AT89C51) and the CPLD(ispLSI 1032),the ultrasonic flow measurement system is designed including the ultrasonic emit and receive circuit, amplify and check circuit, PPL circuit.3. The digital circuit design with the VHDL languageTo improve the stability and reliability of the system, most of digital circuits are integrated into ispLSI(in system programmable large scale integrated chip ) 1032.These digital circuits are realized with the VHDL language and the function simulation is carried out.4. The software design of flow measure systemThe software design is carried out with the assemble language. To deal with many obtained data ,a kind of effective arithmetic is designed on the basis of random error theory and data structure knowledge.5. The analysis of the system errorWith the use and fixing of the ultrasonic heat meter, the analysis is carried out in all aspects that have relation with the ultrasonic heat meter measure accuracy.