Circuits and signal conditioning for a peanut-drying monitoring system

Post-harvest processes at peanut buying points and other peanut grading facilities have a direct impact on the quality of the product. Peanut drying is an essential task for safe peanut storage. The rate at which peanuts are dried can also affect the flavor and milling qualities. Current peanut drying processes require substantial human interaction and often lack efficiency. Therefore, a quarter-scale peanut drying system was developed to study automation of the drying process. This development led to the implementation of a portable peanut-drying monitoring system, capable of measuring drying parameters in real-time on 45-ft semi-trailers. The monitoring system uses a sensor network containing five sensors, one of which is a microwave moisture sensor, capable of in-shell kernel moisture content determination, to monitor drying parameters. These parameters include temperature and relative humidity of the ambient air, temperature and kernel moisture content of the peanut bed, and the temperature of the inlet air. Appropriate signal conditioning was applied to each sensor output so that all voltages would be suitable for the analog to digital converter of the microcontroller. Such implementation would reduce overdrying and underdrying, preserve peanut quality, and provide more efficient control of the heater, minimizing energy consumption and labor requirements.