Making use of these advantages and providing further opportunities for practical experimentation in the Chemical Engineering course at CU, Dr Markus Kraft (Cambridge) and Prof. Clark Colton (MIT) posted a proposal to the Cambridge-MIT Institute (CMI) to use the MIT heat exchanger experiment in the Cambridge syllabus and to develop a second experiment, based in Cambridge, for use by students from both Cambridge and MIT. The proposal was successful and in autumn 2003 assignments and experiments were developed and incorporated in the course. The main part of this work has been carried out by Anders Selmer who has working experience in chemical engineering, teaching, and the web authoring.

The Exercise

Chemical Engineering students at Cambridge perform a variety of exercises that are designed to be an intermediate step between idealised, exam-style questions and long-term, large-scale projects. In previous years, the exercise on Process Dynamics and Control has contained a simulation of a flash tank where the numerical solution of the control equations often occupied more of the students' time and thought than the actual control part. In order to allow the students to focus more successfully on the practicalities of control, this exercise was scrapped and a new one incorporating the MIT heat exchanger was developed by Teaching Consortium Teaching Fellow Mike Goodson and Anders Selmer under supervision of Dr John Dennis who is responsible for the exercises.

The MIT heat exchanger iLab was initially designed to demonstrate the principles of heat transfer but in this assignment the focus is on the controller for the hot water inlet temperature and the actual heat exchanger is only treated as a black box. The technical equipment is designed to run over long periods of time with minimal maintenance and, once set up properly by the MIT staff, it could be run for the complete duration of the course with only occasional supervision.

After completing the initial part of the exercise the students were given usernames and passwords to be able to log in to the experiment and sign up for a timeslot. Each timeslot could be occupied by up to four students. At their allocated timeslots the students logged in again and performed the experimental part. In addition to the experiment interface a chat client is provided to allow the students to communicate with each other and the tutor during the experiment.

In the first part the students made observations of a system under P, PI and PID control, respectively using parameters obtained by applying the Cohen-Coon method to open loop test data. The next part was to improve these parameters by observing the system's response to disturbances and applying knowledge of the equations governing PID control. Finally they had to record the responses to three different step changes.

The Outcome

Students have so far responded positively to the experiments. 'It was very interesting to use a real piece of quite juicy kit, and to operate it over the web,' says second-year chemical engineering student Cameron Saxby. 'It gave us the chance to put some theories into practice, and it really helped me to understand what process design and control is all about.'

'It's very different', says fellow student Andrew Peevor. 'I hadn't had any experience of using a web interface to manage a technical system. But I liked the fact that when we made adjustments, the graphic displays showed the effects immediately, and we then had to decide how to respond to those changes'.