www . refrigerationandaircon . co . za RACA Journal I September 2024 23
Feature
While there has been a shift from water cooling in recent years for environmental reasons , Van der Merwe points out that cooling towers are primarily water-saving devices which reject the heat and return most of the water back to the system - as opposed to the once-through system .
“ The hybrid cooler , featuring a combination of dry and wet modes of operation , offers significant water and energy savings as it fluctuates between different modes based on ambient conditions . This allows for a more efficient and sustainable cooling solution ,” he says .
Dry coolers operate solely based on the ambient dry bulb temperature . While they offer advantages in terms of water consumption , their physical size and weight may pose challenges during retrofitting an installation . Evapco ' s adiabatic dry cooler offers substantial water savings compared to the wet cooler , making it a desirable solution in a world facing climate change , high water costs , and stricter regulations . It is a popular option for companies unable to get water quota in some municipalities .
Regarding the advantages of Evapco ' s adiabatic condensers compared to air-cooled ones , the adiabatic condensers have lower installed power , a smaller footprint , and higher capacity . This means they can provide more efficient cooling in a compact design . The adiabatic pads are installed on the outside of the condenser unit . Additionally , Evapco offers a free cooling system with solenoid valves that activate the pads and introduce water when needed .
Previously , most designs used the pumped pad system , where water recirculates through a pump . However , this can lead to an increase in dissolved solids concentration if water quality is not closely monitored . As a more practical solution , the onestream bed system directs water through the bed and straight to drain . Some manufacturers recommend using mineralised water with the pumped pad system , but this can be expensive . Evapco ' s adiabatic units utilise the one-stream bed system , which eliminates the need for expensive water treatment .
Cooling towers can be broadly categorised into two types : natural draft and mechanical draft . Natural draft cooling towers operate without mechanical assistance , relying solely on the natural flow of air to facilitate heat transfer .
In contrast , mechanical draft cooling towers use fans and motors to drive air through the system , creating a mechanically induced draft . These can further be divided into packaged or factory-assembled products , which range from small to large sizes , and field-erected systems , which are typically used for larger industrial processes .
Within mechanical draft cooling towers , there are variations such as forced draft and induced draft systems . Forced draft cooling towers have fans installed below the cooling tower fill pack , pushing air through the unit , creating positive pressure . Induced draft systems , on the other hand , have fans installed
Supplied by BAC . Supplied by IWC .
BAC HXI Hybrid cooling towers
For Gelatissimo , an authentic Italian gelateria based in Glenhazel , the sporadic cooling water requirements of their machines posed a substantial problem .
on top , pulling air through and creating negative pressure . Each design offers different efficiencies and maintenance requirements , tailored to specific applications .
While there are closed-circuit cooling towers with internal coils , these are technically different from traditional opencircuit cooling towers . Open-circuit cooling towers are designed to cool water by rejecting heat through evaporation , returning most of the water to the system , and minimising overall water consumption .
In recent decades , the industry has seen a shift towards more standardised , factory-manufactured products . This transition has allowed for greater consistency in quality and performance . Evapco , for example , initially focused on the refrigeration market before expanding into cooling towers for HVAC . Today , the company offers a wide range of products designed to meet the needs of diverse applications , from industrial processes to data centres .
www . refrigerationandaircon . co . za RACA Journal I September 2024 23