No hygiene issues in void spaces surrounding -24°C cold store
The supermarket chain Lidl originates from Germany and dates back to the 1930's.
In 1970, the first Lidl store opened and today there are more than 10,000 Lidl supermarkets scattered around more than 20 countries.
In Denmark, 94 stores are daily serving Danish shoppers – and more to come.
Every Danish Lidl supermarket houses its own Bake Off facility. All designed on the same concept and all offering 30+ different freshly baked bakery products.
Within the supermarket area are dedicated Bake Off facilities, consisting of a -24°C cold store and a smaller preparation room where the ovens are placed. The cold store holds the frozen ready-to-bake products that are placed onto trays in racks in the preparation room prior to baking.
High risk of mold growth
When Lidl in Denmark started introducing Bake Off in their shops they were well aware that the void spaces around the cold store would pose a risk of condensation and following mold problems.
The cold store itself is a structure built into a concrete/brick housing with a void space around all 6 surfaces. The height on the upper void space differs, depending on the building in question, but the void space on the remaining 5 sides is a 10-20 cm wide space. This is a normal design of a cold store that prevents the cold from the outer surface of the cold store walls directly transferring the cold onto neighboring rooms, building structures and foundation.
As the cold store is placed within the supermarket, the air around it will be approx. 40°C warmer compared to the -24°C inside. As a law of nature, this leads to condensation on the cold surfaces in the void space.
Lidl's own technical department worked with the contractor on finding a solution to fight the condensation, and Munters' desiccant dehumidifiers were the perfect solution to the problem.
Elimination of condensation
Lidl decided upon one standard concept for all their Bake Off installations that includes a Munters desiccant dehumidifier.
Munters' ComDryM210X was selected as this small unit fits perfectly into the void space and can be wall mounted, taking up only very little space. Placing the unit typically on top of the cold store requires simple duct work that distributes the dry air from the dehumidifier alongside the outer walls of the cold store.
The ComDry works by treating the air from the void space by leading it through the desiccant drying wheel (rotor) of the dehumidifier. The moisture from the air is absorbed by the extreme hygroscopic surface of the slowly rotating desiccant rotor and the dried air is then sent back into the void space. The moisture absorbed by the rotor is removed by means of a heated regeneration air stream that leads the water away as a warm and wet air stream, led outdoor.
By always keeping the dew point in the void space lower than the lowest temperature on the cold surface, Lidl can feel confident that no condensation can occur. At this low humidity level, mold and fungus will not appear and cannot grow. This prevents hygiene issues just as the building structure will be kept dry and unaffected by possible humidity related damages.
The dehumidifier is easy to access and maintain and with the regular maintenance by Munters, Lidl is assured that the dehumidifier will always operate at its best performance with the lowest possible energy consumption.
Cold stores free from ice
On top of controlling the climate around the cold store, Munters also has solutions for inside the cold store. The well-known problems with ice build ups on cooling coils, walls, floors and ceiling can be easily avoided by attacking the cause of the problem: by reducing the humidity in the warmer ambient air at the airlock/entrance to the cold store, the conditions in the cold store itself are improved significantly.
Munters dehumidification solution is also applicable to chill stores where condensation dropping on product surfaces is avoided and HACCP compliance is maintained. Lowering the humidity in food processing areas reduces mold propagation and speeds up clean downs.