(334b) Design Course for Micropower Generation Devices

The widespread use of portable electric and electronic devices increases the need for efficient autonomous man-portable power supplies (up to 50 W). Currently, batteries are the predominant technology in most applications. However, batteries have a large environmental impact, high cost and relatively low gravimetric (Wh/kg) and volumetric (Wh/l) energy density. State-of-the-art batteries reach up to a few hundred Wh/l Wh/kg and the upper limit on performance is now being reached. A promising alternative is to use common fuels/chemicals such as hydrocarbons or alcohols and there is a great military and civilian, interest in developing battery alternatives based on these fuels and portable fuel cell systems.

Research on man-portable power generation is extremely active. There are several academic programs exploring microfabricated fuel cell systems in industry and academia [1]. In the years 2001-2006 the Army Research Office funded a Multidisciplinary University Research Initiative (MURI) at MIT. The aim of the program was to develop fundamental understanding of fuel processing at the micron-scale and to establish the engineering principles needed to realize portable electrical power generation from fuel sources. The size of the processes ranges from the millimeter to micron scale. As part of the program a methodology for optimal system design and operation [1,2,3,4,5,6] was developed. Aspects of this methodology are taught as a design module at MIT (by Paul I Barton) and as a seminar at RWTH Aachen. This talk describes these two courses.

The design module is targeted at students of Chemical Engineering in their senior year. It addresses the development from process-oriented to product-oriented design, e.g., [7]. The course length is six weeks with four hour-long lectures per week. Students work on a team project in groups of three throughout the course. The project scope alternates between the selection of the most promising process alternatives and the optimization of a fixed process structure. In the first half of the course, lectures give a short introduction to chemical product design and build up the material required for the project. In the second half, lectures are replaced by discussion-based class meetings and office hours, to support the students' projects.

The seminar is aimed at graduate-level students in computational engineering. The focus of the seminar is on modeling and methods. It starts with an introduction and motivation. Then it covers the basics of fuel cells and process design at the macro scale as well as numerical algorithms for simulation and optimization. Finally, the various aspects of the methodology are detailed, including the selection of alternatives, detailed modeling, and optimal operation.

Acknowledgment: The author would like to thank Paul I Barton (pib@mit.edu) and Klavs F. Jensen (kfjensen@mit.edu) for the opportunity to design the course and for fruitful discussions.

[1] A. Mitsos, B. Chachuat, and P. I. Barton. Methodology for the design of man-portable power generation devices. Industrial and Engineering Chemistry Research, 46(22):7164-7176, 2007.

[2] A. Mitsos, I. Palou-Rivera, and P. I. Barton. Alternatives for micropower generation processes. Industrial and Engineering Chemistry Research, 43(1):74-84, 2004.

[3] A. Mitsos, M. M. Hencke, and P. I. Barton. Product engineering for man-portable power generation based on fuel cells. AIChE Journal, 51(8):2199-2219, 2005.

[4] B. Chachuat, A. Mitsos, and P. I. Barton. Optimal design and steady-state operation of micro power generation employing fuel cells. Chemical Engineering Science, 60(16):4535-4556, 2005.

[5] A. Mitsos, B. Chachuat, and P. I. Barton. What is the design objective for portable power generation: Efficiency or energy density? Journal of Power Sources, 164(2):678-687, 2007.

[6] M. Yunt, B. Chachuat, A. Mitsos, and P. I. Barton. Designing man-portable power generation systems for varying power demand. AIChE Journal, 54(5):1254-1269, 2008.

[7] E. L. Cassler and G. D. Moggridge. Chemical Product Design. Cambridge University Press, New York, 2001.