PROJECT
INCORPORATING COLD CHAIN
RPP KZN Consulting Engineers RPP KZN Consulting Engineers for a contractor to be pressed for time . This is because the retailer ' s contractor – as opposed to the developer ’ s contractor – is only allowed into the space over the beneficial occupation period . That gives them 60 days . About two weeks before store opening everything has to be running , which effectively leaves only 45 days to do what is a large installation . So there was considerable pressure on the contractor , not because of any unusual delays during the project but rather because that is the only time available ,” he explains .
DIFFICULTIES ENCOUNTERED IN MEETING THE DESIGN , SPECIFICATION AND INSTALLATION
Hlapolosa describes the biggest challenge as revolving around acoustics , being an upmarket shopping mall . Technical
Installation progress in Oceans Mall . interest in the system installation stemmed from where the plant was situated – in the parking lot of the Umhlanga Oceans shopping mall , with the store itself on a level above the parking area . This raised the risk of noise pollution in an upmarket retail environment .
To avoid noise pollution from the refrigeration system affecting the remainder of the mall , the system installation was designed with enough filters and specialised fans connected to the condensers to reduce noise considerably . The system ' s major equipment included compressors from GEA , electronic controllers , cabinets , and multiplexes from Carel , as well as evaporators from Col Coil and Cold Cab .
The cooling , refrigeration , and associated systems for the plant room design of the installation were based on
We have set tight controls so that temperature fluctuations do not far exceed setpoint . This helps with both reducing energy consumption without affecting the food through too high or too low temperatures .
Technical interest in the system installation stemmed from where the plant was situated - in the parking lot of the Umhlanga Oceans shopping mall , with the store itself on a level above the parking area . a multiplex and simplex principle , with 255kWr on MT with 2x multiplex racks and 3x simplexes ; 40kWr on LT with 18 x simplexes . The units are on R404a refrigerant with an estimated COP 2.4 .
“ We have got a structure which increases the suction pressure when it does not need to be particularly cool because the meters may be on temperature cycling , for example . On the condenser fan one can also drop the condensing pressure when the weather permits or if it ' s late at night when it ' s generally quiet . We run them as quiet as possible from an acoustics consideration . Then when there is regular ambient noise during the day , we can run the fans at full speed by dropping condensing pressure ,” says Hlapolosa .
Another issue was the nature of being a coastal environment . “ We could not permit the stainless steel condensers to be exposed to the highly corrosive environment .”
Energy conservation is always an important consideration and what WSP typically does for the Shoprite Checkers brand is to install high efficiency fans on condensers . The retailer has shifted to LED lights within the cabinet as its more energy efficient compared to typical fluorescent lights . “ We have set tight controls so that temperature fluctuations do not far exceed setpoint . This helps with both reducing energy consumption without affecting the food through too high or too low temperatures in the effort to reduce energy consumption ,” he says .
During the commissioning phase and during installation , there was remote control over a central controller of each and every individual controller to establish the setpoint and the alarm , which is accessible every moment . The contractor was able to view remotely adjustable temperature logs on what each cabinet is doing at any moment . This is not a full building management system but a console reading for the systems not interfacing to the rest of the building or store , other than an audible alarm within the manager ' s office , which indicates when there is an out-of-range cabinet .
“ In conclusion , given this is part of a huge upmarket mall installation in Durban , interfacing with the landlord ’ s professional team was more intense than is often the case with much smaller projects . While in many instances such an environment can lead to challenges or clashes of personality , this was not the case in this project . WSP and Energy Partners are seasoned in this type of project and it was really good working in Durban on such a prestigious mall ,” he says .
THE BROADER PROJECT The Shoprite Checkers component is part of a broader project for the entire Oceans Mall , for which the consulting engineers were RPP KZN Consulting Engineers and ADX Consulting Engineers .
Writing in the April issue of RACA Journal , Ashlee Moodley Pr . Eng , director : RPP KZN Consulting Engineers , noted that the design brief was to design a central chilled water plant similar to that of a district cooling plant that would service the various buildings as part of the development . This required multiple chillers , each with standby and duty pumps sets . Efficiency and space requirements played a major role in the
RPP KZN Consulting Engineers
During the commissioning phase and during installation , there was remote control over a central controller of each and every individual controller to establish the setpoint and the alarm , which is accessible every moment .
selection of the chilled water system . Being less than a kilometre from the shoreline , a water-cooled chilled water system was selected for its efficiency and longevity as there are less components exposed to the elements when compared to air-cooled systems .
He writes as follows : “ The central chilled water system was the system-ofchoice based on lowest overall energy consumption , lower maintenance costs and most economical plant space requirements . The same type of system is used extensively for mixed use developments in Dubai . The use of a central system allows better provision for redundancy without duplication in numerous separate systems . It also allows better use of diversity which is substantial in a mixed-use development .
The system provides a long lifespan , in the region of 25 to 30 years with proper maintenance . Overall maintenance costs are reduced as there are fewer moving parts when compared to air cooled alternatives .
The bulk of the power supply is centralised , which is more cost effective and economical . The challenge of recovering energy usage and maintenance is achieved by the installation of energy meters for all users as follows :
• Hotel at main supply
• Residential at each apartment
• Retail at each zone Air Handling Unit
The energy meters accurately measure chilled water flow and temperature to summate kW cooling , allowing apportionment of running and maintenance costs according to actual usage . Each of these meters transmit the readings to the central BMS / Billing System to be provided by the electronics engineer .
AIR CONDITIONING – CENTRAL PLANT The installation consists of a centralised water-cooled chilled water system with multiple chillers consisting of a mix of base load high efficiency centrifugal chillers and
26 www . coldlinkafrica . co . za COLD LINK AFRICA • June 2023