Design and Control of an Air Heater Process

The paper is concerned with the design of an air heater and experimental evaluation of feedback and feed forward control structures to achieve a desired heater outlet temperature by adjusting the heat load in the presence of a measured air flow disturbance. It was found that a combined feedback/feed forward control structure outperforms the simpler feedback only control structure. This experimental study entails the design of the air heater and associated instrumentation, real time data acquisition and control in LABView, process modeling, controller design, and evaluation of the performance of different control structures in a closed loop manner. This work was performed in partial fulfillment of the requirements of the Senior Capstone Project undergraduate course in controls and instrumentation at an Engineering Technology Department. Introduction Process control is part of our daily life. Our house A/C unit uses simple control techniques to maintain room temperature at a comfortable level. Manufacturing companies use process control and automation to gain competitive advantage. They use process control to run safely, environmentally friendly, reliably, and profitably their manufacturing operations. To be able to design and implement effective process control systems, we need to first understand what are and how the major components of a control system function. Process control includes a process, measuring devices (sensors), control algorithms (controller), and final control elements (controlled device). All these are combined in what is known as control loop. Different control algorithms and structures such as Feedback and Feed forward can be incorporated in a control system. Likewise, different tuning methods can be employed. Ziegler Nichols and Cohen-Coon methods. Different tuning methods result in different control performances. Project Objectives The specific project objectives are: 1. Construct the air heater unit (process) 2. Incorporate measuring devices (temperature sensors) and final control elements (heater power) 3. Develop a real-time data acquisition system using LABVIEW 4. Provide temperature control by implementing feedback and feed-forward control structures. 5. Develop empirical process models 6. Explore and apply different control principles (PID control algorithm, Ziegler-Nichols, Cohen-Coon and Auto tuning methods) 7. Test and analyze the performance of the different control structures and tuning methods P ge 25388.2 Description of the Air Heater Process The Air Hea through the tube. A heating element is used to adjust the amount of heat and thus affect the air heater outlet temperature. Two locations. LabVIEW was used to and is shown in Fig. 2 program is shown in Fig. 3 forward stru ter process is shown in Fig. 1 cture, as shown in Fig. 4 -type K thermocouples are used to measure air temperature at two . Also, LABVIEW was used to control the process. The LABV . The control structure is feedback only or a combined feedback/feed