Visualisation and interaction for design

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Presentation made at the ECOSSE Retrospective Symposium, commerating 20 years since the start of the ECOSSE project.

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Visualisation and interaction for design

  1. 1. Introduction Process Integration Water distribution Summary Visualisation and interaction for design Professor Eric S Fraga Department of Chemical Engineering UCL (University College London) ECOSSE Retrospective Symposium Edinburgh 17 April 2009 c 2009, All rights reserved. Visualisation and interaction for design 1 / 20
  2. 2. Introduction Process Integration Water distribution Summary Process design Process design should be informed by robust optimisation with confidence in results. But... complex non-linear, non-convex, discontinuous & noisy models, 1500 Cost versus Pressure 1400 1300 combinatorial search space, 1200 Cost (k$/yr) 1100 small, possibly non-convex, feasible 1000 900 regions, and 800 700 600 0 5 10 15 20 25 30 35 ill- or un-defined objective function Pressure (atm) and constraint equations outside feasible regions. Visualisation and interaction for design 2 / 20
  3. 3. Introduction Process Integration Water distribution Summary The simplest things give me ideas. Joan Mir´ o Visualisation and interaction for design 3 / 20
  4. 4. Introduction Process Integration Water distribution Summary Visualisation and interaction Computer based tools for design and optimization are intended for use by non-experts. Visual representations critical for ease of use. Interaction can enable engineer to apply own intuition. Strategy is to combine data analytics, visualisation, and robust (hybrid) optimisation. Applications in energy, water, carbon capture, sustainability, and control. Visualisation and interaction for design 4 / 20
  5. 5. Introduction Process Integration Water distribution Summary Heat-integrated process design Task: Identify potential integrations for given configuration. Enable process modification for better integration. Help engineer identify design alternatives. Visualisation and interaction for design 5 / 20
  6. 6. Introduction Process Integration Water distribution Summary To simplify complications is the first essential of success. George Earle Buckle Visualisation and interaction for design 6 / 20
  7. 7. Introduction Process Integration Water distribution Summary Visual representation For a given process configuration, we can display the hot and cold streams visually and support interaction, where x-axis for position independent duties, y -axis for temperature, and hot stream overlapping cold stream indicates heat integration. Allow user to manipulate process by moving streams (the tail wagging dog approach): streams can be moved horizontally for different integrations and moved vertically or stretched horizontally to change underlying unit designs. Visualisation and interaction for design 7 / 20
  8. 8. Introduction Process Integration Water distribution Summary HEN design algorithm 1 Define list of intervals A graphical view of ns process heat requirements I ← {{xa,i } ∪ {xb,i }} defines left and right 1 end-points for each hot and cold stream in the 2 For each interval [Ij , Ij+1 ]: process: 1 Generate list of active streams, A. 2 Sort A from top to bottom using yb values. 3 Generate match for each hot stream {(xa,i , ya,i )} immediately above cold stream in A. {(xb,i , yb,i )} 4 Generate utility match for all other streams. i = 1, . . . , ns and 3 Coalesce adjacent similar matches. x, y ∈ Z+ . 4 Design exchanger for each match. 5 Cost all exchangers and utility use. Visualisation and interaction for design 8 / 20
  9. 9. Introduction Process Integration Water distribution Summary Demonstration www ESF, Patel & Rowe (2001). ChERD 79(7):765–776 Visualisation and interaction for design 9 / 20
  10. 10. Introduction Process Integration Water distribution Summary Water distribution networks We wish to design the pipe network for water distribution for a given configuration with the aim of meeting water demand with redundancy in the network. A small motivating problem: 7 nodes 8 pipes 1 reservoir no pumps Alperovits & Shamir (1977), Water Resource Research 13(6):885-900 Visualisation and interaction for design 10 / 20
  11. 11. Introduction Process Integration Water distribution Summary The design problem Given network layout: connectivity, length (Lk ), set of discrete pipe diameters, pipe cost; node demands, Dn ; and, min minimum head requirements, Hn . Determine diameter of each pipe, dk , chosen from the set of discrete diameters; flow amount and direction, Qk ; and, head (pressure) at each node, Hn so as to minimise total network cost. Visualisation and interaction for design 11 / 20
  12. 12. Introduction Process Integration Water distribution Summary The model min Cm Lk ykm k m subject to: Qk − Qk = Dn k∈In k∈On ∆Hk = Hn∈Ik − Hn∈Ok β Qk −γ ∆Hk = w Lk dm ykm CHW m min Hn ≥ Hn + En ykm = 1 m Indices: k, pipes/connections, n, nodes, and m, pipe diameters. Visualisation and interaction for design 12 / 20
  13. 13. Introduction Process Integration Water distribution Summary Direct optimization Solved minlp in gams, using dicopt with the cplex milp solver and a variety of nlp solvers: Initial Solution (103 $) Configuration conopt2 conopt3 minos minos5 None 659 655 444 Fails All flows = 100 441 441 452 452 Initialization affects success of the nlp solvers. Consider visual and interactive tool for initialization of subsequent mathematical programming method: hybrid approach. Visualisation and interaction for design 13 / 20
  14. 14. Introduction Process Integration Water distribution Summary Simplicity and complexity need each other. John Maeda Visualisation and interaction for design 14 / 20
  15. 15. Introduction Process Integration Water distribution Summary Discrete optimization Use of visualization requires mapping from continuous to discrete space. Mapping converts MINLP to discrete programming model ... ... but equality constraints cannot be satisfied in discrete space. So we use interval analysis to identify solutions which are close to feasible in discrete space. The discrete model is solved either by the engineer through interaction or using an embedded stochastic optimisation procedure. Visualisation and interaction for design 15 / 20
  16. 16. Introduction Process Integration Water distribution Summary Interval arithmetic Changes to model given that node heads are now intervals: ∆Hk = Hn∈Ik − Hn∈Ok 1 β ∆Hk Qk = w C Lk γ βd k 0 ∈ Qk − Qk − Dn k∈In k∈On where indicates an interval value. Visualisation and interaction for design 16 / 20
  17. 17. Introduction Process Integration Water distribution Summary Demonstration www ESF & Papageorgiou (2007), Optimization and Its Applications, Springer, 4:311-332. Visualisation and interaction for design 17 / 20
  18. 18. Introduction Process Integration Water distribution Summary Hybrid procedure results Initial Solution (103 $) Configuration conopt2 conopt3 minos minos5 None 659 655 444 Fails All flows = 100 441 441 452 452 Visualisation and interaction for design 18 / 20
  19. 19. Introduction Process Integration Water distribution Summary Hybrid procedure results Initial Solution (103 $) Configuration conopt2 conopt3 minos minos5 None 659 655 444 Fails All flows = 100 441 441 452 452 Hybrid 419 419 423 419 Behaviour of nlp solvers is more consistent. The global optimum is found in 3 of the cases. Solutions obtained are better in all cases. Visualisation and interaction for design 18 / 20
  20. 20. Introduction Process Integration Water distribution Summary Summary To simplify complications is the first essential of success. George Earle Buckle But... Everything should be made as simple as possible, but not simpler. Albert Einstein Visualisation and interaction for design 19 / 20
  21. 21. Introduction Process Integration Water distribution Summary Acknowledgements The following have contributed to the work presented here: Dr Lazaros Papageorgiou, UCL Ms Rupal Patel, UCL Dr Glenn Rowe, Dundee and the ECOSSE group is to blame for my working in this field! http://www.homepages.ucl.ac.uk/~ucecesf/research.html Visualisation and interaction for design 20 / 20

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