The potential structure of the candidate optimal thermal system is modeled as a grammar invoking ... more The potential structure of the candidate optimal thermal system is modeled as a grammar invoking a set of the preferred synthesis rules. This set of axiomatic, user defined rules is translated to a properly defined automaton and graph theory structures. A relatively large number of distinct potential thermal systems can be formulated with this relatively small set of expert system rules. The near-global optimal thermal system (with respect to the topological structure, operational decisions and component parameters / characteristics, simultaneously) is found through an evolutionary-type algorithm. The method is appropriate for the optimal design and operation of thermal power plants that are present in all-electric ships, industrial sector, national-electric power networks, etc. (cogeneration, combined circles, heat recovery, refrigeration plants etc) from the mechanical engineering point of view The method also allows nonlinearities in any user defined objective function and constraints, such as energy/exergy efficiency, economic performance, operational limits, etc.
A flow diagram is a graphical presentation of an energy or chemical system with its components an... more A flow diagram is a graphical presentation of an energy or chemical system with its components and their interconnections through mass and energy streams. An automatic drawing algorithm of flow diagrams has been developed and presented in this article. It heuristically imitates all the procedures carried out by a designer, starting with his conceptual understanding of the system’s topological structure and finishing with graphically representing the system on the paper or screen. The topological structure of the system is given as input in the form of digraph. As a first step, it is transformed to a planar digraph by introducing new vertices representing crossings between the various streams. The near-optimum (smallest) number of crossings is determined heuristically. Then the flow diagram is drawn on the screen using special mechanical engineering symbols for the components of the system. Horizontal and vertical lines represent streams of mass or energy, identified by different colors. Unnecessary expansion of the drawing area is avoided by the application of linear and integer-linear programming algorithms.
The potential structure of the candidate optimal thermal system is modeled as a grammar invoking ... more The potential structure of the candidate optimal thermal system is modeled as a grammar invoking a set of the preferred synthesis rules. This set of axiomatic, user defined rules is translated to a properly defined automaton and graph theory structures. A relatively large number of distinct potential thermal systems can be formulated with this relatively small set of expert system rules. The near-global optimal thermal system (with respect to the topological structure, operational decisions and component parameters / characteristics, simultaneously) is found through an evolutionary-type algorithm. The method is appropriate for the optimal design and operation of thermal power plants that are present in all-electric ships, industrial sector, national-electric power networks, etc. (cogeneration, combined circles, heat recovery, refrigeration plants etc) from the mechanical engineering point of view The method also allows nonlinearities in any user defined objective function and constraints, such as energy/exergy efficiency, economic performance, operational limits, etc.
A flow diagram is a graphical presentation of an energy or chemical system with its components an... more A flow diagram is a graphical presentation of an energy or chemical system with its components and their interconnections through mass and energy streams. An automatic drawing algorithm of flow diagrams has been developed and presented in this article. It heuristically imitates all the procedures carried out by a designer, starting with his conceptual understanding of the system’s topological structure and finishing with graphically representing the system on the paper or screen. The topological structure of the system is given as input in the form of digraph. As a first step, it is transformed to a planar digraph by introducing new vertices representing crossings between the various streams. The near-optimum (smallest) number of crossings is determined heuristically. Then the flow diagram is drawn on the screen using special mechanical engineering symbols for the components of the system. Horizontal and vertical lines represent streams of mass or energy, identified by different colors. Unnecessary expansion of the drawing area is avoided by the application of linear and integer-linear programming algorithms.
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Papers by Denis Grekas