IceDry® combats ice in storage at KLM

90% of the in-flight meals are brought in frozen, and placed in cold storage. The meals can be stored for anything from three days up to six weeks, depending on whether they are for infrequently used special dietary requests. The quick-freezing process means rapid throughput and high product quality demand.

Preparing in-flight meals raises its own difficulties with ambient temperature often ranging from 20 to 30ºC in Summer, and the food preparation areas must be maintained at 14-15ºC, before the products enter the adjacent cold storage freezers at –20ºC. With freezing at these temperatures you get a lot of humidity, on account of the wide difference in temperature and pressure between the ambient air and that in the cold storage freezer.

Moist air streams into the -20ºC store every time the doors are opened, due to the frequent deliveries throughout the day. The result is the frosting and icing up of the floors inside and outside the storage area, icing of refrigeration components, such as the evaporator, and also frosting of product making it difficult for the food technicians to read the product labels.

“The floor was very slippery and unacceptably dangerous, we had to do something” said one employee. “We had ice and snow on the evaporator, it was difficult to clean, and difficult to keep at a constant -20ºC”, we had frequent defrosts, typically six times daily for one hour.”

The Solution

The simple and effective answer was to remove the moisture from the air, and this is exactly what Munters IceDry® systems do so well. KLM Catering Services installed three IceDry® systems in their cold stores, as Munters system is specifically designed for low temperatures. Munters desiccant dehumidifiers work by drawing air from the cold store through a rotor containing silica gel.

In removing moisture from the air, Munters calculates, then controls the dewpoint temperature required - the point at which moisture in the air will condense out and freeze onto surfaces. Once the moisture in the air is removed, the now ultra-dry air is piped back into the cold store area. By removing the moisture, the IceDry® system also assists increase the periods between defrost, reducing energy utilisation and refrigeration plant cleaning.

“The difference before and after the installation of IceDry® is like night and day” says the KLM employee. “The coldstore rooms are clean and the floors are no longer slippery”.

The optimal dry room
The safety improvements also got the thumbs up from the “ARBO” welfare at work organisation. Improving the safe operation of the environment had previously been attempted by adding grip strips into the floor to make it less slippery. This proved unsuccessful as after only two weeks, the ice built up again.

Now with IceDry® this is completely clear. Moving the food pallets is also much safer, and loading is faster, the catering team can read all the labels correctly, without having to wipe the frost off. The improvements have not only been seen in safety, as KLM Catering Services now only defrost once a day for half an hour. It is not strictly necessary, but is done as a precautionary measure for cooling equipment safety.

Previously KCS observed ice build-up on the coldstore fan during the night, which occasionally was so severe that it meant that the fan could not blow anymore. Now this has been completely solved with Munters IceDry®. KCS also found through constant electronic temperature tracking, that they have been able to maintain much tighter temperature control.

The reduced defrost with IceDry® enabled KCS to reduce the temperature of the refrigerant evaporator coolant from –27ºC to – 22ºC. KLM Catering Services see the Munters IceDry® as a primary element of their HACCP initiative for safe and effective working, in short, it has been a great success.