SIMULTANEOUS LAYOUT AND PIPE SIZE OPTIMIZATION OF PIPE NETWORKS USING GENETIC ALGORITHM

A genetic algorithm is used for the simultaneous layout and size optimization of pipe networks. A typical pipe network is a collection of pipes, reservoirs, pumps, and different kinds of valves connected to each other in order to meet specified demand at nodes. An engineering concept of reliability is used in which the number of independent paths from source nodes to each of the demand nodes is considered as a measure of reliability. The method starts with a layout which includes all possible links. The method is capable of designing a layout of predefined reliability including tree-like and looped networks. It is shown that a layout optimization of network followed by size optimization does not lead to an optimal or a near-optimal solution. This emphasizes the need for simultaneous layout and size optimization of networks if an optimal solution is desired. The performance of the method for layout optimization of pipe networks is tested against two benchmark examples in the literature and the results are presented. The first example is considered to show the necessity of simultaneous layout and size optimization even for the simple tree networks, while the second example is considered to illustrate the efficiency of the proposed method for layout and size optimization of networks with different level of reliabilities