Condensation drying is a promising technique for drying and preserving potatoes independently of the outside air. In this first part of a diptych, project leader Marcel Bennink of ENGIE Refrigeration explains how arable farmers can dry their potatoes twice as fast.
For a long time, the agricultural sector was dependent on the outside air to dry and cool crops, but the conditions are almost never optimal. Bennink: "Moist outside air requires compensation by heating with gas stoves. However, when 1 kilogram of gas is burned, 1,6 liters of moisture are released. The potato does not need that. To then dehumidify the space, arable farmers again use uncontrollable (outdoor) air A vicious circle, which affects the quality of the potatoes does not benefit."
In the future (due to climate change) we will have to deal with unpredictable weather events more often. Changes in temperature and CO2 can affect the potatoes and cause them to dry out. The risk of rot nests, pressure marks and peeling waste also increases. Winterizing products without sacrificing quality is therefore becoming an increasing challenge.
Stable conditions
Because outside air throws away the chance of a controlled drying process, ENGIE designed a system that can dry and store outside air independently. Bennink: "The condensation drying system offers optimal conditions, without growers being dependent on the outside air. It is in fact a cooling and heating installation in 1 that makes outside air and gas heaters superfluous."
Bennink continues: "The installation extracts moisture from the air through condensation and discharges it directly to the outside via a drain pipe. As a result, the potatoes dry in a controlled manner from the first minute, regardless of how the products come from the land. Drying is guaranteed for 24 hours. per day and twice as fast as before.”
Wounds also heal twice as fast
In conventional installations, outside air conditions also determine how wound healing progresses. "On average, that takes 10 days. But because the conditions differ from day to day (sometimes from hour to hour), this makes the process uncontrollable and unreliable. With condensation drying, the computer adjusts the conditions to what the potato needs."
Due to the above, wound healing is realized after 5 to 7 days. "That blocks the way for diseases and limits weight loss. The stable temperature in the room ensures that the products remain at the right temperature, even during the storage process† That way, the quality is preserved," says Bennink.
More revenue
ENGIE Refrigeration built a new storage warehouse for Eugene Borgmann, arable farmer in Bottrop, Germany, which is completely mechanically cooled. The computer continuously measures the temperature and humidity in the shed and automatically adjusts the cooling capacity to the cooling demand during drying and storage.
Borgmann: "My potatoes remain of quality and rotten nests are a thing of the past. In 6 months we have had 10% less dehydration and 30% more potatoes. The potatoes remain crunchy, even after six months. If we had cooled with outside air, then they would have become soft by now. Today the last potatoes are still good, so they yield more than before."
Can be used for various products
The condensation drying system can also be used for drying and storing onions and flower bulbs. Arable farmers with a combined cultivation of onions and potatoes, for example, can use it for both crops. Arable farmer Roger Custers uses the system to dry and store his organic onions. "The condenser dryer brings the air into the shed below the condensation point."
As a result, the onions dry twice as fast. "This gives me control. Regardless of how the onions come from the field, the neck is dry within a few days. I can also continue to dry or post-dry the onions during the storage period at a low product temperature. Previously I had to unnecessarily raise the cells too high. keeping the temperature to be able to dry the onions with outside air. Not conducive to the shelf life and my energy bill. Now that is a thing of the past," says Custers.