Type of dryer

Table Column Head

The drying temperature

Advantages

Disadvantages

The greenhouse type solar dryer

≤70˚C

Greenhouse type drying system has the advantages of simple structure, low cost, suitable for basic unit to use. This dryer is suitable for the requirements of drying temperature is low and allows direct exposure to the sun’s material.

The solar energy drying device of hothouse which efficiency is very low receive the solar total radiation energy effective utilization rate is only 15% used for moisture evaporation materials, mostly lost to the atmosphere.

The collector type solar dryer

≤70˚C

This dryer can adjust the temperature of the hot air drying according to the material characteristics; can accommodate more material per unit area, because the material in a dry indoor layer; strength the convective heat transfer so that the drying effect is better. The dryer is suitable for the drugs that could not dry by the sun direct insolate.

Non-permeable air collector with the problems that the top layer of air convection heat absorbing plate or radiant heat loss are more difficult to solve. Permeable air collector had the disadvantages of complex structure, excessive material consumption and complex process. Aggregated air collector with the complex structure does not have the possibility of widespread popularization and application.

The collector greenhouse type hybrid solar dryer

≤70˚C

This dryer has the advantages of both greenhouse and collector type dryer and comparing with the greenhouse type dryer the dry temperature is improved. This dryer is suitable for dry the materials of which have higher water content and need higher temperature to be dried

Drying device area and height are larger. The production process is relatively complicated and the cost is also higher.