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Revolutionary onion drying concept

11 November 2020

This year Tolsma-Grisnich continues the testing of a new onion drying concept in the Netherlands. As quick drying is of the highest importance for maintaining onion quality the R&D department is always working on new storage concepts to maintain onion quality and reduce operational costs. Also the increasing demand for organic onions which are not treated with a sprout inhibitor asks for new storage equipment which can maintain low relative humidity at storage temperature.

One of the new concepts we are testing and fine-tuning at the moment is a plug & play mobile QCC refrigeration unit with condensation drying mounted in an airbag ventilation system for box storage. The advantages of a plug & play cooling unit are combined with the advantages of a forced ventilation system.

The basic plug & play cooling unit is upgraded with a by-pass condenser mounted in the insulation box between de evaporator and the mixing door. The condensation heat that is normally released to the outside air is used for reheating the cooled and dehydrated internal air. This dry air is used to ventilate internally and take up moisture from the onions. The moist air will be cooled down again after entering the evaporator in the QCC unit and moisture will condensate there and drain to the outside.

Advantages of this new concept are that drying becomes independent of the outside weather conditions and will extend the storage period. Also when outside weather conditions are warm and humid, the drying rate is not affected and the onion quality will be maintained. Energy efficiency is also increased because the heat is reused instead of using (gas) heaters to heat (cold) outside air. And there is still the possibility to use outside air when that is suitable for drying.

This season we’re fine-tuning this revolutionary new concept in several storages in Europe. Testing and optimising is done on air distribution and control technology.

Release: the Netherlands, Germany, Belgium, France, Austria, UK, Scandinavia


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