Condensation drying: storing onions independently of the outside air

What is condensation drying?

For a long time, the agricultural sector was dependent on the outside air to dry and cool crops. But due to climate change, the quality of onions stored during the winter is deteriorating. ENGIE Refrigeration has developed a condensation drying system for storing onions, which means you are no longer dependent on the weather. What does that give you? More effective preservation of the quality of your onions and much lower energy costs. In other words, more profit. 

Loss of quality and high costs of storing onions in the conventional way
Onions must be dried as soon as they are harvested. That is usually done using the outside air. However, the quality of the outside air almost never fully meets the requirements to guarantee the quality of the onions during the drying process. To solve this problem, the outside air is heated with gas heaters so that the air can absorb more moisture. This consumes a huge amount of gas. With the additional disadvantage that 1.6 kilos of moisture is released for every kilo of propane gas that is burned. This moisture must also be removed, which in turn requires another 10% of extra gas consumption. So storing onions in the conventional way not only costs money – it also detrimentally affects the quality of the onions. 

In fact, heating the air is not a good idea anyway because the temperature needs to be constant while the onions are being stored. On the one hand, continuing to heat the air causes an undesirable rise in temperature, while on the other hand stopping the process means that the onions can no longer be dried.  

ENGIE Refrigeration has developed a condensation drying system that can be used to dry crops independently of the outside air conditions, and the operational costs are lower than those for conventional systems. That way, storing onions is a win-win situation!  

How are onions stored with condensation drying?
With condensation drying – also called cool-drying – it is no longer necessary to use the outside air or gas heaters. The condensation dryer is actually a cooling and heating system in one. That makes this system unique. With condensation drying, the air is cooled to below the condensation point; this removes a great deal of moisture and dries the onions at the same time. The heat released during the cooling process is then used to keep the onions at a constant temperature. In addition, the system is fitted with a heat pump in order to heat up consignments of onions. The entire system is controlled by an operating system that ENGIE developed itself and that can be operated and controlled locally and remotely using a PC or a smartphone.  

Storing onions: existing technology used in a new way
“The technology used to store onions in this way is not new,” says Marcel Bennink, Project Manager at ENGIE Refrigeration. “We’ve been using this technology for years in cheese warehouses and climate chambers. The results in that sector got us thinking, and they ultimately led to the development of an effective approach for storing onions. Our wealth of experience in a wide range of sectors is helping us stay innovative. It’s inspiring us to translate technologies that work well elsewhere to other markets, and the condensation drying of onions is just one example of that.” 

Like to learn more about storing onions with condensation drying?
Would you like to find out more about how to store onions with this innovative ‘condensation drying’ technology? Then contact Marcel Bennink