On-line moisture sensors have been installed in a commercial cotton gin to monitor cotton moisture during the ginning operation. One sensor was installed in the feed hopper to measure incoming moisture, and two sensors were placed at the dryer exits. Temperature sensors were also installed before and after the air/cotton mix point at the entrance to each dryer. Moisture and temperature data was fed to a portable computer running a commercial software control package which manipulated the drying air temperature to control exit moistures.

A pneumatic ram was used to press the seed cotton against the moisture sensor plate in the feed hopper. The unit functioned well mechanically, however, moisture data from the sensor showed less precision (more scatter) than data from 1990 tests. We believe this is due primarily to elimination of the dual range in 1991 to accommodate the multiplexer. Data from the dryer exit moisture sensors also showed considerable scatter. We believe this is due in part to the need for a dual range for these meters. Another source of variability may be the inconsistent thickness and density of samples obtained by flapper-type sampler used to capture and press the seed cotton against the sensor plates. Due to extremely dry weather, remoisturized cotton samples were used to obtain a wider range of moisture levels and this may have introduced additional variability in all the tests.

The computer-based control system needs further refinement, however, recorded temperature response data clearly shows that it is superior to the existing control system used at the gin.