The Study of Model for Chlorine Transport in the Water Distribution System

• Main Authors: Shi-Bin Wen, 溫士賓
• Other Authors: Hund-Der Yeh
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/65671114749521000628

碩士 === 國立交通大學 === 環境工程系所 === 97 === The residual chlorine concentration in a water distribution system concerns safety of drinking water. A mathematical model can be used to describe the transport behavior for chlorine in a pipe. This model is mainly make up of two dimension chlorine transport equation (CTE) considering the mechanisms of advection and dispersion in axial direction, the diffusion in radial direction, and the first-order decay reactions in the bulk liquid phase and at pipe wall. Many numerical techniques were utilized to solve the 1-D model and only few studies have been devoted to the development of analytical solution in this area. This study first derives the analytical solution of unsteady CTE in turbulent flow through utilization of Laplace transform and generalized Fourier series expansion, which is to simplify differential term in the radial direction. This solution is further simplified in absence of dispersion in axial direction and integrates with a series of methodology to establish an analytical model for simulating the chlorine residual at any location in a water network. This analytical model is used to predict the chlorine concentration distribution in the water network of the South Central Connecticut Regional Water Authority (SCCRWA). The simulated results are compared with those obtained from a mass-transfer-based model developed by Rossman et al. (1994). Moreover, an approximate solution of the 2-D steady-state chlorine transport equation under turbulent flow is also developed. This new approximate solution has advantages of easy evaluation and good accuracy when compared with Biswas et al.’s approximate solution (1993). This thesis also develops a methodology which combines simulated annealing (SA) with this new approximate solution to determine the wall decay parameter. Two cases are chosen to demonstrate the application of the present approximate solution and methodology. The first case is to use this new approximate solution in simulating chlorine decay in pipes with the experiment-observed data given by Rossman (2006) while the second case presents the determination of the wall consumption at the end of pipe in the water network of SCCRWA.