Sustainable and efficient cooling in our new distribution centre
A high-tech cool box and an installation to freeze cooling elements? Of course, we design them ourselves!
Efficient and sustainable refrigerated transport
Our colleagues of Collect&Go searched for a way to transport refrigerated products to both stores and customers' homes. After all, for home delivery, our traditional refrigerated carts are less interesting. Project manager Peter De Bonte: "Our R&D department started working on this assignment and elaborated some cool box prototypes. We tested them extensively in various areas. How much heat loss is there, are they ergonomic, how is the stability, how long do our products remain cold, etc. We searched the market, but did not find anything that met all our requirements. In the end, we designed and developed the cool box completely in-house."
The boxes keep the right temperature thanks to specially developed refrigeration elements. Of course, these first have to be cooled themselves. Peter: "For that as well, we looked at different options. Among other things, we considered freezing tunnels, but in the end, we opted for a plate freezer that works with contact cooling. Compare it to a waffle iron, but cold. We already use this kind of machines for freezing food, but freezing refrigeration elements is a new thing. That it would be a big installation was clear: Collect&Go needs around 3000 refrigeration elements daily."
The 6 'waffle irons' in the installation can each cool 18 refrigeration elements simultaneously. The water in the refrigeration elements freezes in about ten minutes. For comparison: a chest-type deep-freeze from our stores can refrigerate 7 pieces in 24 hours. Peter: "Currently, the process is still semi-automatic, in time we will fully automate it. An operator takes the cassettes from the cool box and puts them on a conveyor belt, after which the machine takes over. After the condensation is blown off the refrigeration elements, they are entered into the plate freezer and refrigerated, after which they move to the buffer tower. If an operator needs refrigeration elements, the machine will offer these from the buffer via a conveyor belt. The buffer tower has room for around 1500 refrigeration elements.
Refrigeration in two steps
Of course, such a robust machine needs a really big cooling installation. The cooling is done in two steps. Project engineer Kristof Lauwereys: "Our propane chillers take care of the first step. They cool the condenser heat of the CO2 cold production. The latter produces cold CO2 of -38°C. We pump that cooled CO2 through our plate freezer, which cools our refrigeration elements. It is a closed circuit, so no CO2 is released in the cooling process. We recover the heat released in the cooling process and we are currently already using it to heat our social rooms and offices."
The faster the distribution centre grows, the more we will cool and the sooner we can make the transfer to heat recovery. In a first instance, orders will be picked in Londerzeel for around 30 stores, but the intention is to scale-up quickly.
The choice of propane chillers is well-considered. Kristof: "We are firm believers in propane cooling and also apply it in other distribution centres and store buildings. The installation in Londerzeel is built completely according to our own design and concept. For example, we made sure that the most important components are on the outside. This makes it a lot easier for our technicians to work on the installation. Moreover, we developed and programmed the hardware control entirely in-house. This allows our technicians to check alerts from a distance and to intervene really quickly in case of malfunctions.
Internet of Things
Our cool boxes remain cool for 20 hours - in summer conditions. Peter: "In winter time, this will be even longer. For us, the development of the cool box was a pilot project on the Internet of Things (IoT). Each cool box has individual temperature measurement: a sensor in the box passes on its temperature to receivers in the distribution centre and the collection points via Bluetooth. This allows us to monitor the temperature continuously. This is important for food safety. We combine that temperature with information about the orders in the boxes. After all, the temperature itself is irrelevant when there is nothing in the cool box."