Design Of Granular Feed Moisture Detector Based On Dielectric Properties

Granular feed is the main physical form of feed products,with comprehensive nutrition and good stability.Moisture content is a basic indicator of pellet feed quality,directly affecting the quality of feed products and their storage properties.The detection of moisture content is one of the important technical means in the production of pellet feed.At present,the determination of moisture content usually adopts the atmospheric pressure oven drying method.Although the method has stable results and high precision,the measurement period is long and cannot meet the technical requirements of rapid non-destructive testing.Therefore,to study the rapid detection method of pellet feed moisture,and to develop a rapid non-destructive detector for pellet feed moisture,it is of great significance for enriching the feed moisture detection method and improving the detection level.In this paper,pig pellet feed was taken as the research object.The concentric shaft cylindrical capacitor and LCR bridge were used to carry out the experimental study on the dielectric properties of pellet feed.A fast particle moisture detector based on dielectric properties was designed.Using the self-designed pellet feed moisture rapid detector,the particle moisture prediction model was established by the test,and the rapid detection of the moisture content of the pellet feed was realized.The main research contents and conclusions mainly include:(1)The experimental study on the dielectric properties of pellet feed was carried out.Taking pig pellet feed as the research object,different measurement frequencies(1kHz~200 kHz),temperature(10°C~30°C),water content(9%~18%),bulk density(461kg/m~3~657 kg/m~3)were measured.The relative dielectric constant of pellet feed,the influence of measurement frequency,temperature,water content and bulk density on the relative dielectric constant of pellet feed was analyzed.The test results show that in the non-compacted state and a certain temperature and water content,the relative dielectric constant of the pellet feed decreases with the increase of the measurement frequency;in the non-compacting state and a certain measurement frequency,the pellet feed The relative dielectric constant increases with increasing temperature and water content;at a certain measurement frequency and temperature,the relative dielectric constant of the pellet feed increases with the increase of bulk density.(2)Designed the hardware system of moisture detector with STM32F103ZET6microcontroller as the core.It mainly includes a capacitance detection module,a temperature detection module,a quality detection module,a human-computer interaction module,a serial communication module,and a single-chip control module.The capacitance,temperature and bulk density of the pellet feed sample are detected,and the test results are displayed on the display screen.Based on the design of each module,the circuit board of the moisture detector was designed and fabricated.Finally,the protective case of the protection circuit board is designed,and the display screen,the load cell and the like are installed together with the protective case to complete the hardware design of the moisture detector.(3)A software system for the moisture detector was prepared.Using the C language,using a modular programming idea,the software system of the moisture detector was written.The software system mainly includes a capacitor collection subroutine,a quality collection subroutine,a temperature collection subroutine,an OLED display subroutine,a moisture content calculation subroutine,and a key recognition subroutine.Through the performance detection and verification of each functional module,the accuracy of the capacitance detection module is±0.7 pF,the accuracy of the temperature detection module is±0.2°C,and the accuracy of the quality detection module is±7 g.(4)Established a prediction model for the moisture content of pellet feed.The self-designed pellet feed moisture detector was used as a measuring tool to study the relationship between relative dielectric constant and bulk density,temperature and water content of pellet feed.Multivariate regression analysis was carried out to establish a prediction model of pellet feed moisture content.The results show that the bulk density,temperature and water content have a significant effect on the relative dielectric constant of the pellet feed.The established moisture content prediction model has a coefficient of determination R~2 of0.9939 and a standard deviation SE of 0.12.(5)The measurement accuracy of the pellet feed moisture detector is empirical.The self-designed pellet feed moisture detector was used to predict the moisture content of the predicted sample using the established particle feed moisture prediction model.The results show that the water content is in the range of 9%~18%,the temperature is in the range of10°C~30°C,and the bulk density is in the range of 577.1 kg/m~3~633.3 kg/m~3.The absolute measurement error value between the dry measurement results is within±0.6%,and the moisture content detection response time is less than 5 s,which has certain practical value.