2014-03-19
10:15 at HCI J 574

Entropy production minimisation

Signe Kjelstrup

Department of chemistry, Norwegian University of Science and Technology, Trondheim

The lecture will discuss why it is important to determine the entropy production of industrial processes, and how this can be done in practice (S. Kjelstrup, D. Bedaux, E. Johannessen and J.Gross, Non-equilibrium thermodynamics for engineers, World Scientific, Singapore, 2010). As examples, some simple process units will be described. For these, it is possible to obtain an analytical solution to the problem of how to operate a process with minimum total entropy production. The solution is characterized by constant local entropy production in the unit. Numerical solutions will be given for energy efficient operation of chemical reactors, using the reformer as an example (Ø. Wilhelmsen, E. Johannesen and S. Kjelstrup, Energy efficient reactor design simplified by second law analysis, Int. J. Hydrogen Res., 35 (2010) 13219-12231). The solution, which applies to cases which have highly non-linear flux-force relations, has a surprisingly constant entropy production, provided that the boundary conditions are not too strict. This then leads to the formulation of the so-called highway hypothesis for energy efficient design. It is speculated that such designs can be found in nature. The lecture is concluded with some rules of thumb for energy efficient design.