PTQ Q4 2025 Issue

Future-proofing cooling systems in a changing climate

Refinery case study illustrates how integrating advanced heat exchanger technology into existing systems can significantly reduce energy consumption

Viswanth Ramba, Sebastian Fogel, and Rahul Patil Alfa Laval

U tility and process cooling systems are coming under increased scrutiny for their energy consumption and environmental impact as the global industrial sector works to meet aggressive net-zero emissions targets. This is especially visible in refineries and petrochemical com - plexes located along coastlines, where seawater-based cooling loops confront increasing performance issues due to biofouling, rising ambient temperatures, and ageing equipment that is underperforming. Recent advancements in plate heat exchanger (PHE) design have enabled more effective solutions to complex operational challenges in the energy sector. A detailed case study from one of the world’s largest refineries illus - trates how integrating Alfa Laval’s next-generation heat exchanger technology into existing systems can signifi - cantly reduce energy consumption and emissions, while future-proofing critical cooling infrastructure. These upgrades reflect the growing impact of global innovators in heat transfer technology. Seawater-cooled systems are common in many coastal industrial facilities due to the availability and thermal capac- ity of seawater. However, the corrosive and fouling char- acteristics of seawater pose problems to heat exchanger dependability and efficiency. Mineral scaling, biofouling, and particle deposits all degrade heat transfer surfaces over time, raising operational costs. In high-capacity industries like refining, where heating and cooling systems account for more than 20% of total energy demand ( source: IEA ), inadequate heat exchanger efficiency has a significant impact. Energy losses from poor cooling result in higher carbon footprints, shorter equip- ment life, and higher maintenance expenses. This necessi- tates a strategic focus on enhanced thermal technologies. Characteristics influencing heat exchanger efficiency The heat exchanger’s long-term performance depends on a balance of heat transfer efficiency, fouling resistance, and permissible pressure drops. Hence, understanding the composition of seawater (sulphates, chlorides, corrosive, and other scaling elements) is required for an effective heat exchanger design. The following sections provide a brief overview of the significant concerns and distinguish the essential characteristics that influence performance.

Fouling mechanism The heat exchanger performance is evaluated through effi - ciency, which is described as the ratio of real to ideal per- formance and can never exceed a value of one. Simulations often represent idealised performance limited by physical constraints in line with the second law of thermodynamics. Establishing this theoretical benchmark enables the evalua- tion of real-world efficiency while considering field system characteristics and actual operational conditions. Understanding fouling phenomena is particularly impor- tant for achieving optimal performance in high-saline envi- ronments such as the Middle East. The three main fouling mechanisms include crystallisation (scaling), biological fouling, and particle fouling. Crystallisation scaling is caused by the precipitation of calcium salts (CaCO₃, CaSO₄), and at high temperatures, solubility is decreased, typically aggravated by the inverted solubility phenomena. Table 1 shows an overview of the impact of precipitation on various parameters. With biological fouling, organic compounds such as bio- films (complex populations of bacteria) can have a major impact on heat exchanger efficiency. Extracellular polymeric substances (EPS) produced by bacteria can adhere to heat exchanger surfaces, promoting the formation of biofilms, which act as insulating layers. Specifically, these foreign materials start to grow on the corrugated channels of plate surfaces, minimising overall performance. Biofouling is con- sidered the major factor, particularly where the water is drawn from stagnant areas (with no adequate circulation). Particulate fouling is mainly caused when suspended materials, such as sand and silt, physically block the flow and insulate the heat transfer surface of the plates. The source of

Rate of mineral and salt precipitation vs dependent variables

Temperature Precipitation influences more rapidly at higher temperatures Salinity Rate of precipitation increases with salinity Fl ow rate

Precipitation is inversely proportional to the flow rate Precipitation occurs at a higher pace with lower pH levels

p H

Table 1

PTQ Q4 2025