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Energy Systems Diagramming

Energy Systems Diagramming. A Systems language...symbols, conventions and simulation…. What is a system?.

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Energy Systems Diagramming

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  1. Energy Systems Diagramming A Systems language...symbols, conventions and simulation…

  2. What is a system? • A system is a group of parts which are connected and work together. Systems with living and nonliving parts are called ecosystems (which is short for ecological systems).(Odum, Odum, and Brown, 1997)

  3. Why a systems language? To convert non-quantitative verbal models to… more quantitative, more accurate, more predictive, more consistent, and less confusing network diagrams

  4. Understanding systems… Understanding environment and society as a system means thinking about parts, processes, and connections. To help understand systems, it is helpful to draw pictures of networks that show components and relationships.

  5. Visualizing systems… • With a system diagram, we can carry these system images in the mind. And learn the way energy, materials, and information interact. • By adding numerical values for flows and storages, the systems diagrams become quantitative and can be simulated with computers.

  6. Systems Language…

  7. Symbols continued...

  8. Symbols continued...

  9. Symbols continued...

  10. Systems are organized hierarchically

  11. Language Conventions….

  12. Procedures for Drawing a Systems Model • Draw the frame of attention that selects the boundary • Make a list of the important input pathways that cross the boundary • Make a list of the components believed to be important • Make a list of the processes believed to be important within the defined system.

  13. Procedures for Drawing a Systems Model • Remember that matter is conserved. • Check to see that money flows form a closed loop within the frame and that money inflows across the boundary lead to money outflows. • Check all pathways to see that energy flows are appropriate.

  14. Procedures for Drawing a Systems Model 8. If color is used, the following are suggested: Yellow – sunlight, heat flows and used energy flows Blue – circulating materials of the biosphere such as water, air, nutrients Brown – geological components, fuels, mining Green – environmental areas, producers, production Red – consumers (animal and economic), population, industry, cities Purple - money

  15. Procedures for Drawing a Systems Model 9. If a complex diagram has resulted (> 25 symbols), redraw it to make it neat and save it as a useful inventory and summary of the input knowledge. Redraw the diagram with the same boundary definition, aggregating symbols and flows to obtain a model of the desired complexity (perhaps 3-10 symbols). (Odum and Odum, 1996)

  16. Diagramming Conventions…. Production & Consumption…a simple ecosystem.

  17. Diagramming Conventions…. A more complex diagram of a forest...

  18. Diagramming Conventions…. Adding more complexity...

  19. Diagramming Conventions…. A generic ecosystem...

  20. Diagramming Conventions…. A city & support region...

  21. Diagramming Conventions…. Ecological Engineering

  22. Diagramming Conventions…. Coupling humanity and environment

  23. Picture Mathematics…. Drawing systems diagrams explicitly writes mathematical equations expressing relationships between flows and storages

  24. Picture Mathematics…. Flows…are the result of FORCES The units of energy flows are “power”…Joules/time The units of material flows are “rates” …kg/time J1 E J1 = k1*E

  25. Picture Mathematics…. Rate of Change Equation Rate of change of the storage “Q” is equal to the inflows minus the outflows...

  26. Picture Mathematics….

  27. Picture Mathematics…. Equational structure…consumer

  28. Picture Mathematics….

  29. Modeling Definitions… • Model – a simplified concept within the human mind by which it visualizes reality. • System – can be defined as a set of parts and their connected relationships. (Odum and Odum, 1996)

  30. Modeling Definitions… • Steady State – when the storages and patterns in an open system become constant with a balance of inflows and outflows. • Equilibrium – refers to any constant state, but generally refers to a closed system when the storages become constant.

  31. Modeling Definitions… • Aggregation – simplifying a system, not fragmentation • 5 to 20 units • Include energy and material budgets • Representation of levels of energy hierarchy • Include feedback pathways • Calibration – giving a model numerical values

  32. Modeling Definitions… • Validation - Compare what is known about the real systems performance • Sensitivity - Analysis of how sensitive outcomes are to changes in the assumptions.

  33. Steps in Developing and simulating a model. The usual approach…

  34. Steps in Developing and simulating a model Energy Systems approach

  35. Modeling…. Wetland hydrology

  36. Modeling…. System Diagram of Wetland Hydrology

  37. Modeling….

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