A Prototype of Photovoltaic Dryer for Nutraceutical and Aromatic Plants

In the past, the interest in nutraceutical and aromatic plants mainly concerned the derivatives and ingredients industries, while nowadays their growing use occurs in different sectors, such as functional food (nutraceuticals), infusion drinks (herbal teas) and bio-ecological cosmetics. The microbiological quality of nutraceutical and aromatic plants is an important criterion for buyers. In order to reduce the bacterial load of these plants, Italian producers impose specific hygiene rules, that mainly concern the operations carried out between harvest and packaging, i.e. the drying process. The drying process takes place at low or high temperatures, from 20 to 50 °C. This type of drying can be obtained by means of a device equipped with a heat pump: drying is obtained by applying very dry air (having a humidity of 5%) to the dehumidified products and heating them up to the desired temperature. This process allows to rapidly dry food, by preserving its colour, aroma and chemical composition, thereby obtaining high quality products. This work describes a prototype of dryer powered by a photovoltaic Renewable Energy Source (RES) for nutraceutical and aromatic species produced in Sicily. The aim of this work is to satisfy the yearly consumption of the dryer through the energy produced by the photovoltaic generator, mounted on the roof and one of the facades of the dryer structure (on-site exchange and self-consumption of electrical energy). The yearly potential production of the photovoltaic generator is 8383 kWh. A total electrical energy consumption of 190 kWh is estimated for each drying cycle. Thus, the dryer can be used for up to 44 drying cycles a year using the energy produced by the photovoltaic generator. The prototype of the photovoltaic dryer will allow to monitor and control the drying process, in order to identify any critical points during it, as well as the failures occurring inside the drying chamber.