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Thahirah Arief
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Bonewa Estate Blok I No. 16, Pattalassang, Gowa, South Sulawesi, 92172, Indonesia
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INDONESIA
Journal of Green Chemical and Environmental Engineering
Published by Candela Edutech Indonesia
ISSN : -     EISSN : 30902568     DOI : https://doi.org/10.63288/jgcee.v1i1.1
Core Subject : Science, Social, Engineering,
Chemical Engineering, Chemistry & Bioengineering Chemistry Engineering Environmental Science Materials Science & Nanotechnology
Aim and Scope : ✅ Green Chemical Processes ✅ Renewable Energy Technologies ✅ Waste Management and Valorization ✅ Pollution Control and Mitigation ✅ Sustainable Materials ✅ Sustainable Process ✅ Food Chemistry ✅ Environmental Risk Assessment ✅ Cleaner Production and Industrial Ecology ✅ Water and Wastewater Treatment ✅ Climate Change Mitigation ✅ Environmental Chemistry ✅ Biochemistry and Biotechnology ✅ Education in Chemistry
Arjuna Subject : Teknik Kimia (semua kategori) - Kimia Proses dan Teknologi
Articles 32 Documents
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Reduced-Order Modeling, Hopf Bifurcation, and Bifurcation-Aware Optimal Control in Nonlinear Reacting Fluid Systems Lakshmi Sridhar
Journal of Green Chemical and Environmental Engineering Vol. 2 No. 3 (2026): Journal of Green Chemical and Environmental Engineering
Publisher : Candela Edutech Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.63288/jgcee.v2i3.31

Abstract

Oscillatory instabilities arising from the nonlinear interaction of reaction and transport processes can significantly degrade the performance, stability, and safety of reacting fluid systems. Reduced-order models provide an efficient framework for capturing the essential nonlinear dynamics while enabling systematic bifurcation analysis and optimal control design. A nonlinear reduced-order framework is developed by projecting the governing partial differential equations describing coupled momentum and scalar transport onto a low-dimensional modal basis, resulting in a four-dimensional dynamical system with two velocity modes and two reactive scalar modes. Stability and bifurcation analyses are performed using MATCONT to identify Hopf bifurcation points and limit cycle dynamics. An optimal control problem is subsequently formulated in Pyomo.DAE and solved using IPOPT to minimize oscillatory energy while incorporating a bifurcation-aware constraint that prevents operation near the Hopf boundary. The bifurcation analysis identifies a Hopf bifurcation at a critical Damköhler number, where a complex conjugate pair of eigenvalues crosses the imaginary axis. The optimal control results demonstrate that incorporating the Hopf bifurcation avoidance constraint suppresses oscillatory dynamics, achieving approximately a 90% reduction in the objective function compared with the unconstrained formulation. The proposed reduced-order modeling and control framework provides a low-dimensional, physically motivated representation for investigating oscillatory instabilities in reacting fluid systems. Integrating bifurcation analysis with optimal control provides a computational strategy for maintaining stable operation and suppressing self-sustained oscillations. The present model is intended as a conceptual proof-of-principle framework; validation against full-resolution simulations or experimental reacting-flow data remains an important direction for future work.
Analysis of the Effect of Inlet Pressure and Feed pH on Permeate Conductivity Stability in a Reverse Osmosis Unit at a Coal-Fired Power Plant Andi Fajri Haryansyah; Sinardi
Journal of Green Chemical and Environmental Engineering Vol. 2 No. 3 (2026): Journal of Green Chemical and Environmental Engineering
Publisher : Candela Edutech Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.63288/jgcee.v2i3.32

Abstract

The Reverse Osmosis (RO) unit in the Water Treatment Plant (WTP) of a coal-fired power plant plays a vital role in producing low-conductivity demineralized water for boiler feed. Permeate quality stability is strongly influenced by operating conditions, particularly inlet pressure and feed pH. This study evaluates the effects of inlet pressure and feed pH, both partially and simultaneously, on permeate conductivity as an indicator of RO performance stability. A quantitative approach was applied using industrial operational data obtained from the SCADA system and log sheets from 8 November 2025 to 30 January 2026. Twenty data points under normal operating conditions without cleaning in place (CIP) were analyzed over an inlet-pressure range of 0.57-0.65 MPa and a pH range of 8.32-8.83. Multiple linear regression and coefficient of variation (CV) analysis were used. The results show that inlet pressure significantly affects permeate conductivity (p-value < 0.05) with a positive regression coefficient. Feed pH also has a significant effect (p-value < 0.05), with a negative regression coefficient (−0.5456). Simultaneously, both variables have a significant effect, with a coefficient of determination (R²) of 82.24%. These findings confirm that inlet pressure and feed pH are dominant parameters and should be jointly controlled to maintain stable permeate quality in industrial RO operation.

Page 4 of 4 | Total Record : 32

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