Design, development and experimental results of a solar distillery for the essential oils extraction from medicinal and aromatic plants

摘要

Distillation of medicinal and aromatic plants for essential oils extraction can be done by utilizing heat in medium temperature range. These essential oils are used in foods, medicines and cosmetics etc. and are money earning business for the farming community. This research is focused to develop an on-farm solar distillery for the processing of different plant materials. The system comprises of a Schef-fler reflector and a complete set of distillation system. An 8 m2 'projected area of the Scheffler solar concentrator was coupled with the distillation still for the extraction of essential oils. In this paper, a complete mathematical description has been explained to design different components of solar distillation system. In order to provide a fixed focus on a receiver from morning to evening and in summer and winter, flexible crossbars have been used to achieve the desired shapes of the reflector. The paper also covers all the details regarding design, development, site specific installation and tracking system etc. Different types of Florentine apparatuses were used to separate the essential oils from the hydrosol. Necessary instrumentation was used for the performance evaluation of solar distillery. The system was capable of producing 300-450 ℃ temperature at the receiver section within the beam radiation range of 800-850 W m~(-2). The efficiency of solar distillery was calculated to be 33.21% with 1.548 kW thermal power available for processing in the distillation still. The system was operated for 10-12 h a day during summer. About 18.58 kW h thermal energy was obtained from the solar distillery in a sunny day. For the processing of 10 kg batch, an average 3.5 kW h energy was consumed. In this way, about 4-5 batches were processed successfully using different kinds of plant materials with 10-20 kg per batch. The research concluded that different kind of medicinal and aromatic plants could be processed effectively using solar distillery.