Study On Controlling System For Alfalfa Solar Drying Based On PLC

With the international energy supplies being increasingly short and enhancing of the people's awareness of the environmental protection,solar energy has been widely used in many fields as a kind of exhaustible new energy which doesn't pollute the environment and damage the ecological balance,without exploitation and transportation.The capability of the controlling system directly affects the quality and efficency of solar drying.Against the current home and abroad situation of solar energy drying by manual operation,low degree of automation,this article provides a method of closed loop centering on PLC, and studied the hardware and software of the controlling system of the computer.The main content of this paper is listed as follows:1)Based on the controlling demand of theme,according to experiments, found the relationships among the exit temperature of air blower,solar radiation, temperature of heat collection, temperature of environment and wind speed of air blower.2)Having designed the hardware and software parts of the controlling system.3)This system can improve the experiment accuracy by adopting PID arithmetic.4)Having Developed a set of user interface can be through drying process for automatic control and data acquisition system.5)Having realized the communication between upper monitor and PLC.6)Having corrected PID data according to analog experiment to make the control exacter and achieve the expected target fast.The result of the experiment proves:this controlling method can improve the degree of automation, improve data accuracy effectively,offer controlling experiment data for the study of solar energy drying technology.