@misc{9239663,
  abstract     = {{The increasing global demand for energy and the need to reduce industrial emissions have made energy efficiency a central focus in process industries. Therefore, this thesis investigates system-level optimization strategies for a closed-loop cooling system utilizing seawater. A system commonly used in heavy process industries, with a focus on both design and operational improvements. The study evaluates how tightening the temperature approach in a plate heat exchanger, e.g lowering the process water outlet temperature from 40 °C to 37 °C impacts the sizing of equipment, pump performance, energy and water consumption and CO₂ emissions. Simulations show that reducing the temperature of the process water can decrease the pumping energy by 14%. Even if production emissions increase by 34%, operational emissions remain the main contributor to the overall footprint and can be reduced by 15% annually. As a result, the total footprint decreases over time, with a payback period of approximately 3 months. However, this approach also increases seawater consumption by 18% and capital expenditure by 14%, due to the need for larger heat exchanger areas and upgraded pump designs. Since seawater is the main contributor to total operating costs, tighter temperature approaches are not economically feasible.

The thesis further analyzes the effects of seawater fouling in plate heat exchanger and effects on system performance. Fouling reduces heat transfer efficiency and increases pressure drop, resulting in higher pumping energy demand and seawater consumption. The results indicate that a 10% reduction in heat transfer performance can increase process water temperature by approximately 1 °C and pressure drop by about 12%, while mitigation through increased seawater flow may rise operating costs by up to 31% and pressure drop by more than 50%. Lastly, the analysis shows that performing cleaning-in-place (CIP) at a 5% k-margin, rather than 10%, could reduce annual operating costs by approximately 0,5 MEUR and better maintaining system performance.

Overall, the results in this study highlight that successful optimization of industrial cooling systems requires balancing energy efficiency, economic performance and fouling management to achieve sustainable system operations.}},
  author       = {{Molander, Ingrid and Vedlugaite, Belinda}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{System-Level Optimization of a Closed Loop Cooling System for Energy Efficiency : An Aspen Plus simulation of temperature programs, fouling effects and mitigation in plate heat exchangers and centrifugal pumps}},
  year         = {{2026}},
}