RESEARCH IN SOME MEDICAL PLANT DRYING PROCESS
The drying process by free convection of six different medical plants (flowers of garden marigold (Calendula officinalis) leaves of lemon balm (Melissa officinalis) origanum (Origanum vulgare) common agrimony (Agrimonia eupatoria) common lavender (Lavandula angustifolia) and common sage (Salvia officinalis) is compared. The constant and changing drying coefficients are determined using the gravimetric methods of measurement and a special mathematical evaluation methodology. Theoretical and experimental results are compared. The experimental results show that the drying coefficient of a plant at the first 10 hours of drying is changing linearly until it becomes constant. The corresponding linearity is strong, characterized by high coefficients of determination. The changes of speeds of sample drying rate are approximately equal, except lemon balm, which is more than twice greater than the others.