www. refrigerationandaircon. co. za RACA Journal I June 2025 13
Associations louvres, which act as a primary filtration mechanism by preventing debris and large particles from entering the cooling tower while blocking direct sunlight.“ This shading effect mitigates algae growth by reducing the presence of warm water and light— two key factors contributing to algae formation. The term‘ darkroom louvres’ has been introduced, as their function is similar to traditional photography darkrooms that limit light penetration.”
A comprehensive comparison between open and closed-circuit cooling towers was provided. Open circuit systems expose water directly to the atmosphere, allowing efficient heat dissipation through evaporation but requiring more frequent water treatment due to environmental exposure. In contrast, closed circuit systems use a heat exchanger to separate process water from cooling water, reducing contamination but increasing system cost and maintenance complexity. While open circuit towers offer a cost-effective solution with lower initial investment, closed circuit systems are preferable in applications where uncontaminated process water is critical.
Maintenance challenges, particularly for closed circuit coils, were addressed.“ Over time, scale buildup and corrosion can reduce efficiency, necessitating chemical treatments such as acid cleaning. However, excessive chemical use can degrade components, limiting system longevity. In regions like the Western Cape, where environmental factors influence wear, closed circuit towers typically last 15 – 20 years with proper maintenance, whereas fibreglass open circuit towers can last indefinitely with adequate servicing,” said Burgess.
“ Proper bleed-off management, a process of removing concentrated water and replacing it with fresh water, helps prevent scaling and corrosion, maintaining system efficiency. Experts suggest a bleed-off rate of approximately 15 % of the evaporation rate.”
Emergency maintenance strategies, including the use of chemical treatments to expedite cleaning, were debated. While rapid circulation was deemed the most effective method, Burgess cautioned against uneven chemical distribution due to varying water velocities.
“ The risk of overloading cooling towers with excessive water flow can disrupt air and water dynamics, reducing efficiency. Proper nozzle selection and pressure monitoring are recommended to ensure flow rates stay within design parameters.”
The conversation also covered Legionnaires’ disease, which thrives in warm water environments like cooling towers. Routine testing and biannual water sampling were recommended, particularly for businesses in hospitality and healthcare sectors, where the risks of litigation and reputational damage are significant.
Emerging solutions for Legionella control, including probioticbased treatments, were also introduced. These treatments use beneficial bacteria to outcompete Legionella, offering an environmentally friendly and cost-effective alternative to traditional chemical disinfectants.
The event concluded with insights into the water treatment industry’ s reluctance to adopt non-invasive technologies, despite their potential benefits. Probiotic-based treatments, which prevent biofilm buildup, were cited as an example of innovative solutions in cooling systems.
Attendees left with a deeper understanding of cooling tower management, from maintenance best practices to emerging technologies aimed at improving efficiency and safety. The talk emphasised the importance of ongoing research and innovation in the industrial cooling sector. RACA
www. refrigerationandaircon. co. za RACA Journal I June 2025 13