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Events and Exhibitions
EXPLORING THE EFFICIENCY OF EVAPORATIVE COOLING
By Eamonn Ryan, derived from the presentation
At a AERSA CPD points training session, Mark Hakbijl, a thermodynamics and adiabatic cooling expert at OXYCOM, presented a compelling case for the potential of natural cooling methods, particularly in the context of sustainable building design.
He demonstrates how evaporative cooling can help meet climate control regulations and align with global climate protocols like Kigali, all while significantly improving energy efficiency in modern buildings.
Hakbijl ' s presentation focuses on the stark difference in energy and water consumption between evaporative cooling systems and conventional air conditioning. Evaporative cooling works by utilising water to cool the air, offering an energyefficient alternative to traditional compressor-based systems.“ For instance, evaporative cooling systems can use 1 000l of water per hour to produce 700 kW of cooling. This process is not only 90 % more energy-efficient than conventional air conditioning systems, but it also uses 70 % less water.”
He observes that globally, producing 1 kW of electricity requires about 10l of water per hour. In the US alone, commercial buildings consume 420 TWh( terawatt hours) of electricity annually for cooling, which equates to the use of 4.28 km ³ of water. If just 1 % of these systems were switched to evaporative cooling, the country could save approximately 4 TWh of electricity and 0.03 km ³ of water, which is comparable to the annual water usage of Namibia.
HOW EVAPORATIVE COOLING WORKS At the core of evaporative cooling is the process of water vapour diffusion.“ Essentially, when water evaporates, it absorbs heat, which cools the surrounding air. Evaporative cooling exploits this principle by accelerating the natural process using air flow. The energy required for evaporation is significant, as it breaks the molecular bonds between water molecules to transform the liquid into vapour,” says Hakbijl.
He highlights that water is one of the most powerful refrigerants available, but requires substantial energy to convert from liquid to vapour. Though this conversion is influenced by temperature( warmer temperatures make evaporation easier), the fundamental energy demands remain high. This powerful process is at the core of evaporative cooling ' s effectiveness.
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RACA Journal I May 2025 www. refrigerationandaircon. co. za