Flake Agricultural Drying Process Control

Drying is the crucial process for agricultural production. As an important component of mechanization of agricultural production, drying technology of agricultural material includes two important aspects:drying method and drying quality evaluation. Up to now, practical operations indicate that hot air drying is still the most economic and simplest method of drying technology. On the other hand, because different agricultural material shows different physical and chemical properties, there are complete different methods of drying quality evaluation. The criterion of evaluating quality in drying one agricultural material does not adapt to drying other.The research regards rose petals as sample. The purpose is explor for control requirement of equipment which realize drying flaky agricultural material process. The experimental equipments include oven, condensator, and sensor of temperature, sensor of humidity, controller and interrelated electric equipments. Drying property of flaky agricultural material was experimented and researched. The research define technologic parameters and evaluate drying qualify by digital image processing. After then, research will design control system by microcontroller unit. It can adapt to local condition and realize drying engineering economically and practically. The paper summarizes methods, conclusions and improved measures in every stages according to order of experiment and design step by step.The research requires distilling water in flower. Acording to the structure of oven, mathematical and physical equation of thermal transfer model is established. Then, the condition of border is defined and temperature distribution in oven is solved. Accoding to the characters of drying object and process, the drying flaky material technology of rose petals is designed and corresponding measure subject of parameters is defined.Research establish model of control system and define control parameters, design its control flow by programmable logic controller and realize control project by electric equipments. The experiment show there is different influences of drying quality between process in high temperature and low temperature. In order to quantify influence of drying quality, the research analyzes and defines optimal drying temperature by.digital image processing. Then, the data were experimented and collected to express relation between temperature, humidity and time during drying process under optimal temperature and conclude its drying property. For predict drying degree of material under different situation and time, the research simulate its drying property by artificial neural network and offer a kind of scientific method for research. The experiment show the drying temperature can not be precisely control by periodic PID control arithmetic. Therefore, the research design control system base on discrete PID arithmetic by microcontroller unit. It can control phase by SCR in order to obtain precise drying temperature.Though control project was precisely realized by discrete phasic PID arithmetic, drying efficiency still relatively low. Because of drying property of flaky agricultural material is decided by inner water transfer regulation. The thinner the rose petals are, the higher drying efficiency is. Under the condition thickness of single rose petal can not be changed, the drying object was moved during drying process and cause whole rose layer become thinner relatively. For improve efficiency, the research theoretically analyze, design base on experiment in the end of paper, The research design new drying equipment in which the drying object was continuously moved. Since drying degree under mobile condition can not be measured by gravity, therefore, image processing is introduced and used to analyze drying quality real-time, automatically continuously take photograph and identify drying object. The result can be communicated with microcontroller unit by serial port. Finally, control demand can be realized by control mobile system.