COMPRESSORS & COMPRESSED AIR


CHILLER CHOICES FOR EFFICIENT PLASTIC PROCESSING


Chris Ferriday, Business Line Manager, Process Cooling Solutions, Atlas Copco Compressors UK, explores the critical importance of thermal management in plastics manufacturing and considers the cooling technologies that help improve operational efficiency and product quality


he plastics industry is a cornerstone of modern manufacturing, producing a vast array of products that are integral to daily life, from pipes and guttering to furniture, flooring, automotive components and toys, as well as medical or food-grade packaging. Whatever the production method – injection moulding, blow moulding, thermoforming or extrusion – the heat generated during the production process must be managed effectively to ensure consistent product quality and to optimise efficiency. Cooling is a vital part of the plastics production process because it helps to solidify the plastic material after it has been shaped. Without proper cooling, the plastic may not solidify correctly or stick to the mould, leading to defects and inconsistencies in the final product. By optimising the cooling process, manufacturers can reduce cycle times, which increases throughput and productivity. Proper cooling also supports product integrity because it ensures that the plastic parts do not warp, shrink, or develop internal stresses that could compromise their structural integrity. For instance, if the cooling is too rapid or uneven, it can cause the plastic to crack or become brittle. Conversely, insufficient cooling can lead to parts that are too soft and prone to deformation. Maintaining precise control over the cooling process is crucial for producing high-quality, reliable plastic products.


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Effective thermal management even extends to keeping other essential equipment, right down to the lubricants in machine gearboxes, at the optimum temperature. Proper cooling helps to prevent overheating


12 FEBRUARY 2025 | PROCESS & CONTROL


and excessive wear on machinery, thereby extending equipment lifespan. This not only reduces maintenance costs but also minimises downtime.


Various methods of process cooling are available, each with its benefits and limitations. Air chillers work on the principle of evaporative cooling. A pump circulates water from a tank onto a series of cooling pads. A fan or blower draws warm air through these wet pads, which absorb the heat and reduce the temperature. Air coolers are more energy efficient than air conditioners, making them more cost-effective. They do not use refrigerants, which makes them more environmentally friendly, and with few moving parts, they have modest


maintenance requirements. Air coolers provide energy- efficient and eco-friendly cooling,


especially in dry climates. However, their


effectiveness can be limited in larger or already humid spaces. Water chillers use water and a refrigerant to absorb heat from the manufacturing process. They comprise four essential components: an evaporator, a compressor, a condenser, and an expansion unit. The water absorbs process heat, circulates to a cooling tower where the


heat is evaporated away, and is then recirculated back to the chiller.


Water-cooled chillers are generally more energy-efficient than air-cooled equivalents because water is a better medium for transferring heat. They can also handle larger cooling loads and are quieter in operation. However, they can be more expensive to buy, require more space and have more complex installation and maintenance requirements. Hybrid chillers combine the principles of both air-cooled and water-cooled systems. The chiller absorbs heat from the process using a refrigerant, which transfers the absorbed heat to a heat exchanger. The heat exchanger is cooled by air through fans and is sprayed with water to enhance the cooling effect through evaporation. The cooled refrigerant is then recirculated. Combined chillers can optimise cooling


efficiency because they can better adapt to changing environments, using more air in cooler climates and more water in hotter climates. This improved efficiency offers reduced energy consumption and cost savings over time. However, hybrid chillers are more complex to design and maintain. Process cooling technology is constantly evolving to improve reliability, energy efficiency, and drive down lifecycle costs. The development of more advanced materials with improved heat transfer properties has enabled free cooling methods, which use natural changes in air pressure caused by volume expansion to regulate temperature. For example, the AXpro from Eurochiller (pictured below) is a versatile process water chiller that can integrate multiple energy- saving technologies in a single solution to optimise efficiency and energy consumption in both winter and summer seasons. As well as being more energy efficient, some chillers even feature energy recovery technologies. The Eurochiller EVVS features an inbuilt Seasonal Energy Performance Ratio (SEPR) and also offers the option to use R454B refrigerant, which


helps reduce greenhouse gas emissions.


Increased connectivity between systems to improve operational efficiencies, enable predictive maintenance and optimise uptime is another area of focus. Monitoring packages, such as SmartLink from Atlas Copco, capture live data from compressed air and cooling equipment to give clear insights in real-time. This gives plastics manufacturers immediate


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