From the outside, the Cilmor Distri­b­u­tion Center (DC) is quite impres­sive. The futur­istic building’s hori­zontal ellipse is nestled in the South African soil, presenting its metal cladding to the sun as if it were a lizard. However, the heat must not pene­trate into the seem­ingly infi­nite rows of high bays on the inside. After all, they house the cheese, juices, meat prod­ucts, and other perish­able goods of around 500 suppliers that are waiting to begin their journey to the show­cases of Shoprite and Checkers stores.

At the highest point of the roof supported by steel beams, the building measures 22 meters and its widest point is 144 by 123 meters. These dimen­sions are gigantic for a reason. With 2,700 stores and 15,000 employees, the Shoprite Group is the largest on the African conti­nent. The Group central­ized its distri­b­u­tion chain upon opening the ware­house in 2018. This means storing food with a wide range of temper­a­ture require­ments under one roof.

With a goal of this magni­tude, it is not easy to create the ideal climate for all goods. The cooling system must be extremely clever. To achieve this, Cilmor DC is divided into three zones. Two have -28 °C freezers measuring 4,500 square meters each and the third 12,000 square meter cooling zone holds the temper­a­ture at 1 °C.

Wanted: econom­ical cooling

That keeps things fresh. But when so much space is being cooled, noise is inevitable – resulting in an unpleasant working climate. “Noise!” said Hannes Steyn, Director of GEA Refrig­er­a­tion Africa (Pty) Ltd., naming the special chal­lenge for this type of building. GEA is respon­sible for the entire cooling system there. Steyn explained that the highly reflec­tive surfaces and many fans, result in a noise level that makes it unpleasant to work in the facility. Where devices make noise, lots of energy is consumed – a second hurdle for the model distri­b­u­tion center, consid­ering that elec­tricity is scarce and there­fore expen­sive. The region does not have enough high-perfor­mance power plants.

Compa­nies that want to operate a building with these exte­rior dimen­sions at the required low temper­a­tures with as little energy consump­tion and noise as possible need to estab­lish rigorous criteria for the main sources of noise and elec­tricity consump­tion. Shoprite spec­i­fied the following criteria: The fans for the evap­o­ra­tors had to be effi­cient and have a maximum noise level of 48 dB(A) – no louder than a quiet night in a major city. Their reach had to be at least 28 meters with 100% speed control.

Plenty of cooling for little energy

AxiCool fans from ebm-papst meet all of these require­ments. And they go even further, as Steyn said: “When it comes to airflow and reach, they exceeded our expec­ta­tions.” “They” are the 176 EC AxiCool fans that generate powerful air circu­la­tion using the heat exchanger surfaces in the evap­o­ra­tors (Fig. 3). The AxiCool Fans that ebm-papst devel­oped espe­cially for commer­cial and indus­trial evap­o­ra­tors and air coolers have a reach of up to 63 meters and air perfor­mance of up to 24,600 cubic meters per hour. They are ideal for gigantic Cilmor DC.

In both freezer sections of the Shoprite distri­b­u­tion center, the fixed-speed axial fans in size 800 with 1.5 kW motor ensure a constant temper­a­ture below freezing. The reason for the fixed speed in these sections is a simple one. The temper­a­ture must be a constant -28 °C, so the fans must deliver a constant airflow. In the freezing sections, the focus is not on whether the tech­nology is quiet because employees do not work in them for long periods of time. The fans could also easily handle temper­a­tures between -40 and +40 °C (Fig. 4).

Energy consump­tion is more impor­tant at the temper­a­tures that must be main­tained there. This would also be a reason for Shoprite to rely on AxiCool. Equipped with guide vanes for improved effi­ciency and with the special AxiBlade impeller design, they keep elec­tricity consump­tion low. These impellers are made of resis­tant composite mate­rial. The blade geom­etry featuring a special profile and winglets deliver higher effi­ciency than conven­tional blades.

A further plus when it comes to saving energy: the drive in AxiCool fans. Green­Tech EC motors stay cool even at maximum power, meaning that heat transfer in the freezer sections is extremely low. AxiCool can reduce power consump­tion by up to 46 percent. The impeller design, opti­mized inlet ring, and intel­li­gent diffuser also ensure that the cooling process is extremely quiet.

The advan­tages of AxiCool fans are partic­u­larly useful in the cooling section of Cilmor DC because many people work there. The required speed in this area is based on the air temper­a­ture and requires the infi­nitely vari­able control func­tion. When the required temper­a­ture is reached, it decel­er­ates. For a gigantic ware­house facility that seldom oper­ates at full capacity, this trans­lates directly into savings – of money and energy.

Smoothly deflect soiling

With their quiet oper­a­tion and effi­ciency, the fans meet two basic require­ments for use in the distri­b­u­tion center. But another attribute is impor­tant where food is being stored: the fans must be clean. Thanks to their optimal distri­b­u­tion of cold air and high splash water protec­tion (IP 54), AxiCool fans comply with the most rigorous hygiene stan­dards. The surfaces were consciously designed to be smooth and do not have any visible screws, making another contri­bu­tion to clean­li­ness. They make it diffi­cult for soiling to adhere and in case of doubt, are easy to clean. This also saves water.

Time is another scarce resource that Shoprite has conserved by selecting ebm-papst fans. One reason why GEA Africa was commis­sioned to call for bids from cooling system suppliers was the company’s agree­ment to complying with the tight schedule that Shoprite had planned for completing the distri­b­u­tion center. ebm-papst reacted by reor­ga­nizing orders and freeing up capacity so it could produce the fans on schedule.