PTQ Q4 2025 Issue

Improving cooling limitations in industrial refrigeration systems during summer weather

Design phase

Existing facilities

Design key components, especially the condenser and compressor, with sufficient capacity margins to provide desired cooling even during the hottest summer days when ambient temperatures are at their maximum. Optimise process integration and heat recovery to maximise pre-cooling, which reduces the load on the refrigeration system.

Install water spray or misting systems that pre-cool the

air entering fin-fan condensers.

Optimise process flow rates and target temperatures. Sometimes, processes might be cooled more than necessary. Fine-tuning the cooling set points can reduce the load. Advanced process control can help to reduce refrigeration load. Regularly purge non-condensable gases from the condenser. These gases accumulate and increase condensing pressure, hindering heat transfer. Consider installing variable frequency drives (VFDs) for fans/compressor to optimise air/refrigerant flow based

Choose refrigerant that exhibits more favourable thermodynamic

properties in high ambient conditions.

Integrate control systems that can automatically adjust the compressor/fan speed (using VFDs) based on cooling demand

and ambient conditions.

on the demand/ambient conditions.

For air-cooled condensers in suitable climates, consider evaporative cooling systems to leverage wet-bulb temperature benefits during high ambient conditions. Design the condenser with a dedicated section to maximise the subcooling. Match the refrigeration temperature supplied to the actual process cooling demand, rather than running the entire system at the lowest required temperature. Based on the process load, design a system with segregated multiple suction pressure levels or a multi-stage compressor configuration. Apply adequate and well-maintained insulation to all cold piping, vessels, and equipment. The effectiveness of insulation

Identify and mitigate any hot air recirculation paths around the condenser that can reduce its effective cooling capacity.

Regularly clean heat exchangers and other cooling surfaces to ensure optimal heat transfer coefficients. Adjust fan blade pitch to maximise the air flow.

Regularly check the condition of insulation in cold lines to minimise unwanted heat ingress into the refrigerated

directly impacts heat leak.

areas or processes.

Table 5

by the main condenser’s ability to reject heat to the ambient air, which in turn is dependent on heat load, the ambient air temperature, and the design/size of the condenser. Adiabatic cooling, also known as evaporative cooling, functions by utilising the principle that water absorbs a significant amount of heat when it evaporates. This pro - cess helps to lower the temperature of the air, making it very beneficial in hotter weather, especially for systems like fin-fan condensers. By supplying the condenser with cooler intake air, the LMTD between the refrigerant and the cooling air in the condenser increases, helping to lower the condensing temperature and, consequently, operate at a lower compressor discharge pressure. Adiabatic cooling systems introduce water as a fine mist into an airstream at the fin-fan cooler inlet. As this water evaporates, it draws the necessary latent heat of vapour- isation from the surrounding air. These systems are most effective and provide the greatest temperature reduction when ambient temperatures are high and relative humidity (RH) is low. As they rely on the evaporation of water, this leads to significant water usage. In addition to the pumping cost, the supply of demineralised water adds to the oper- ating cost. The use of water makes these systems suscep - tible to issues like scaling, fouling, and biological growth. This necessitates regular cleaning, inspection, and may also need water treatment programmes. Table 5 shows recommendations to improve cooling

limitations in industrial refrigeration systems during summer weather, separated for new designs and existing facilities. Conclusion Efficient process cooling in hot climates poses significant challenges for conventional systems. Hydrocarbon-based refrigeration offers a reliable alternative; however, extreme ambient temperatures severely impact its performance. To counter these limitations, it is crucial to implement robust design strategies and operational improvements. Recommendations include oversizing components, opti- mising process integration, selecting appropriate refriger- ants, utilising advanced control systems, and maintaining proper insulation and cleanliness. By addressing these fac - tors, industries can ensure consistent cooling efficiency and enhanced plant performance even under severe climatic conditions. A site-specific financial evaluation is crucial to determine the true suitability and return on investment for any proposed solution. Susheel Moudgil is a Lead Process Engineer at DUGAS, Dubai Natural Gas Company Limited, Dubai (ENOC Group), with more than 23 years of experience in the refining and petrochemical sector, specialising in hydroprocessing, catalytic reforming, C3/C4 dehydrogenation, and MTBE synthesis. Moudgil holds an M.Tech in chemical engineering from the Indian Institute of Technology Roorkee and a PG diploma in renewable energy from the University of Petroleum and Energy Studies, Dehradun.

PTQ Q4 2025