Experimental Formulation of a Reynolds-Number- and Wall-Reaction- Based Correction Factor for Chlorine Transport in Pressurized PVC Pipes

Sumardi Sumardi; Farida Gaffar

doi:10.51988/jtsc.v7i4.736

Authors

Sumardi Sumardi Department of Water Resources Engineering, Faculty of Engineering, Universitas Muhammadiyah Makassar, Makassar, Indonesia
Farida Gaffar Department of Water Resources Engineering, Faculty of Engineering, Universitas Muhammadiyah Makassar, Makassar, Indonesia

DOI:

https://doi.org/10.51988/jtsc.v7i4.736

Keywords:

Reynolds number, Correction factor, Chlorine transport, Wall reaction, Pipe network

Abstract

Accurate residual-chlorine prediction in pressurized water systems can be affected by the way one-dimensional models aggregate radial transport and pipe-wall processes. This study develops an empirical Reynolds-number-dependent correction for chlorine transport using controlled loop experiments. A 20 m PVC loop with a nominal diameter of 2 in was operated at eleven Reynolds numbers from 500 to 30,000. Each condition was tested in triplicate; chlorine was restored to 1.5 mg/L before each run and residual concentration was recorded hourly for 72 h. The analysis used a dimensionless wall-related term Z and a worksheet-defined percentage error E. For each Reynolds-number group, the normalized response was calculated as ? = E?/Z? and fitted with a power law in logarithmic space. Parameter uncertainty and predictive performance were assessed using 95% confidence intervals, MAE, RMSE, MAPE, and leave-one-Reynolds-group-out cross-validation. ? decreased from 0.300650 at Re = 500 to 0.003466 at Re = 30,000. The fitted relationship, ? = 0.1306(Re/1000)^?1.063, produced R² = 0.9967, RMSE = 0.0094, and MAPE = 5.69%; cross-validation yielded RMSE = 0.0140 and MAPE = 6.95%. The formulation is therefore proposed as a compact diagnostic correction within the tested PVC-loop range and should not be used as a substitute for system-specific hydraulic and water-quality calibration.

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