The Design Of Electronic Soap-film Flowmeter

Flow expressed mass (Kg/h) or volume (m3/h) of fluid flowing over in per unit time. Flow is an important parameter in the industrial production and scientific experiments, both in the industrial production and scientific experiments required for the measurement of flow to account productivity of process and equipment, the proportion of flows of every portion ,to evaluate the process and equipment. Meanwhile flowmeter also has a wide application in environmental protection and the measurement of daily life.The design of the electronic soap-film flowmeter based on the optical principle to detect film, which have functions of automatic detection of soap film, automatic timing, and automatic correcting of flow with the temperature and pressure of the gas, so it will decrease the error by judging the film artificially. The key of the design is to design a low-cost and reliable means of detecting the location of soap-film and the methods of data collection of temperature and pressure.The soap film is more transparent and thin, and I can't detect the film inside the pipe, so I design a method to detect the soap -film base on optical principles, it is low-cost and reliable. In practice, place the infrared transmitter and the infrared receiver on two sides of flowmeter, the soap-film will disturb the infrared when it passes them, the signal should be disposed and send to Microcontroller.In hardware design, the system adopts the digital temperature sensor DS18B20 to detects temperature. The DS18B20 is 1-Wire interface requires only one port pin for communication and requires no external components, it can be powered from data line and measures temperatures from -55℃to + 125℃, and±0.5℃accuracy from -10℃to +85℃. the system adopts the MPX2100 to detect pressure whose measurement range from 0Pa to 100Pa.AD7705 is used as interface of MPX2100 and Microcontroller.The method of pulse modulation is used in software design to minish DC interference of other lamp-house, so it can detect soap film more exactly. The electronic soap- film flowmeter can calculate flow automatically with Timing by timer inside the Microcontroller, the temperature and pressure.The circuit is simple, easy operation, high reliability and can effectively reduce the error of artificial seeing the soap-film and timing, and reached the paper design goals.