Gregory E. Ogden, Chemical & Environmental Engineering, University of Arizona, 1133 E. James E Rogers Way, Tucson, AZ 85721 and Anthony J. Muscat, Chemical and Environmental Engineering, University of Arizona, P.O. Box 210011, Tucson, AZ 85721.
This paper presents initial findings and results of the department's ongoing effort to modernize experimental facilities and incorporate data acquisition systems into the undergraduate laboratory. Labview programming was used to teach the process control course that students take in the second semester of their senior year. This was likely their first introduction to Labview. In the past Matlab with Simulink was used to model process control systems. Although the Matlab environment is powerful and flexible, Labview was chosen because of the capability to communicate with external equipment via a USB based interface. Measurement Computing USB devices were utilized for both temperature (USB-TC) and analog (1208FS) signal processing. The students learned basic Labview programming along side controls. Beginning with simple computer-based assignments, the students developed and debugged virtual instruments (vi's) of increasing complexity until they wrote complete data collection and control vi's that were used to control a two-tank in series experiment. The Labveiw assignments were all geared around controlling liquid levels and flow into two tanks in series. Early projects were designed to provide experience in data manipulation, using the front panel and annotating the block diagram to explain the process. Students created a vi to graphically indicate the height of water in a tank as a function of volume. These vi's were expanded to include subvi's designed to correlate pressure sensor input data to liquid level which were tested in the lab. Students gathered voltage vs. flow data and developed correlations that were used in Labview to control pump flow. Finally, students used tank height and pump flow correlations in a dynamic vi to control the liquid level in a second tank to a desired setpoint using a PID algorithm. Labview provided students with a means to acquire data, perform analysis, and output results to control a system. This experience should give students a better insight into the complexities of effective controller design. The faculty intend to introduce Labview programming earlier in the ChE curricula so that students can take full advantage of its DAQ and control functions when they take process controls. This will allow faculty to develop more involved computer and experiment-based activities that will help students to better relate control theory to actual practice.