A self-contained, bench-mounted apparatus to demonstrate basic and advanced principles of control of single and coupled tanks, including the study of static and dynamic systems.
• Self-contained and compact bench-mounting unit
• Electrically-heated and air-cooled model process that mimics a real industrial process
• Includes variable hysteresis for advanced process control experiments
• Temperature sensors with diff erent thermal contact to the process give variations in thermal inertia and time constant
• Front panel includes mimic diagram of the process so students can see what they are controlling
• All inputs and outputs buff ered for connection to TecQuipment’s optional controllers or other suitable controllers
Description
The Thermal Control Process Apparatus mimics a common industrial process, including an air-conditioning plant, where a combination of adjustments can control temperature. These can be:
• Varying the heat energy input to the system
• Varying the speed of a circulating fan
• Using a variable vane to restrict the flow
The apparatus has a variable-speed fan that forces air through a duct. In the duct is an electrically-heated process block. A balance of the heat gained from electrical heating and heat lost by convection and conduction gives a steady temperature at the block.
Two temperature sensors measure the temperature of the block. One sensor is in direct thermal contact with the block. The other sensor mounts on an insulating spacer to introduce thermal inertia and variable-time constants into the control loop. A servo-driven vane, mounted after the fan and the process block, creates a variable restriction downstream for more advanced experiments.
The control problem is to keep the process temperature within acceptable limits while it works under various conditions. A combination of regulating the electrical energy to the heater, varying the air fl ow rate and rotating the vane gives the heat control. The apparatus has scaled-down time constants for shorter laboratory time.
A relay amplifi er with variable hysteresis allows more advanced experiments.
Learning Outcomes
• Heat transfer
• On/off control – experiment includes investigation of overshoot and undershoot, on and off time ratio, rates of heating and cooling, off set and hysteresis
• Proportional, proportional + integral, or proportional + integral + diff erential control • Frequency response of model process
• Thermal inertia and variable-time constants
• Multi-variable control – up to three variables can be monitored and individually controlled
The fl exible design of the equipment allows the user to develop many other analysis and control exercises to suit their needs. It is good for extended or advanced control experiments, and is ideal for student project work.
Essential Base Unit
• Controller (CE120) – A controller with analogue and digital controls and instruments or
• Digital Interface (CE122) – An interface which connects between most products in the Control Engineering range and a suitable computer (not included) or
• Other suitable controller with +/– 10 V inputs and outputs
Both the CE120 and the CE122 include TecQuipment’s CE2000 Control Software (see separate datasheet) with editable, pre-made control experiments for use with the CE103.
