Papers Published

  1. Bejan, A. and Lorente, S., Equilibrium and nonequilibrium flow system architectures, Heat and Technology, vol. 22 no. 1 (2004), pp. 85 - 92 .
    (last updated on 2007/04/06)

    This paper reviews the progress made on the development of constructal tree networks: step by step improvements in global performance (e.g., global flow resistance) subject to global constraints (e.g., size of flow territory, total tube volume). This leads to a graphical and analytical formulation of the constructal law of maximization of flow access under constraints. If the flow structure is free to change, then the structure progresses toward 'states' that are closer to 'equilibrium'. The equilibrium flow structure is the one that enjoyed most freedom to change; here the performance level is the highest, and does not change even though structural changes may occur. In addition, there is an infinite number of 'nonequilibrium' flow configurations the performance of which is inferior to that of equilibrium configurations. Nonequilibrium architectures enjoy limited freedom to morph. The infinity of nonequilibrium structures occupies a region (cloud) in the space where the coordinates are global performance, freedom to morph, and global constraints. The equilibrium structures occupy the surface that bounds the region occupied by nonequilibrium structures. The analogy between this formulation of the flow architecture space and the thermodynamic formulation of the equilibrium-nonequilibrium space is stressed.

    Energy conservation;Entropy;Ducts;Trees (mathematics);Functions;Bifurcation (mathematics);