The forced air flow allows a better hot air distribution through the trays, improving
the importance of the convective transfer compared to the radiative process and
improving the drying uniformity.
Another important improvement is the carts system, with its continuous product
charge and discharge facility improving its handling and reducing the worker labor.
This is an important point to evaluate the commercial drier feasibility.
The tunnel greenhouse drier presented an acceptable load capacity, i.e. fresh product mass by unit area, around 50 kg/m2, if only the tunnel area where the product
is placed is computed. This ratio is reduced if the collector zones are considered.
However, these zones can be used as a temporary storage for the dried product or
to place the semi-dried product, improving the final load ratio.
A change in the initial design, incorporating an auxiliary energy source, is necessary to work during high humidity days. Also, a complementary energy source will
allow an increase of the working time interval, improving the drying rate and the
drier production. The non-renewable energy consumption is increased, but assuming
that the biomass obtained from agricultural surplus is used, the conventional energy
savings would still be considerable.