Drying processes for herbs and foods with renewable Energy independent from weathear conditions


• Use of thermochemical fluids TCF (aqueous solution with NaOH or LiCl) for drying process.
• Drying process at low temperature, no damages of the goods.
• Drying process driven by stored renewable energy

The absorption process is very suitable for the drying of agricultural goods like herbs and fruits, which must be dried immediately after harvesting regardless of the weather conditions.

The air is dried in an absorber in counterflow with a concentrated TCF but is not necessarily heated, as heat could harm the leaves/vegetables and affect their quality. In a closed cycle, the released dry air is then injected to the dryer room where humidity of the vegetables can be extracted. The diluted TCF can then be stored without thermal loss and regenerated when renewable heat (e.g. solar heat) is again available. In comparison to state of art systems using compression dehumidifiers, in a sorptive dryer, the electrical energy consumption is limited to the operation of fans and liquid pumps, while the thermal energy required can be entirely provided by a low temperature heat source, e.g. can be totally renewable. After the regeneration process, the energy provided also can be stored without any losses.

The sorptive dryer uses solar heat as energy source. Energy flows for a state of art drying plant operating with compression dehumidifier (left) is compared to the energy flow for the proposed solution. The electrical energy for the proposed solution is drastically reduced and the thermal energy can be entirely stored, i.e. can be totally renewable.

Components
Absorber/desorber
They have the same design of the absorber of Solution 1, but in this case a control of the temperature of the TCF is not necessary.

Drying box
The substance to be dryed is inside a box with a perforated floor. The dry air flows through the holes of the floor.