مرکز منطقه ای اطلاع رساني علوم و فناوري - A solar distillery of essential oils with compound parabolic collectors (CPCs)

Abstract :

A new essential oil distillation system was developed to produce the essential oils of medicinal and aromatic plants by water-steam distillation. This distillation system was composed of solar CPCs and distillation units. The solar CPCs unit comprised of seven solar compound parabolic collectors (CPCs), having 3.4 m² aperture area 1.9 concentration ratio. The distillation unit had a distillation tank, a condenser and an oil separator. The distillation unit was sized to distill 5 kg plant material each batch. 5 k g water steam was passed through 5 kg plant pile. The heat gained by solar CPCs was transferred to the distillation unit to boil distillation water. An electrical heater was placed at the bottom of distillation tank to complete distillation processes in case of insufficient solar energy supply. Three distillation trials were conducted in August. One of trials was conducted by covering the CPC reflectors with a black fabric sheet to determine the contribution of concentrating solar irradiance. Experimental data such as solar radiation intensity, temperatures of water, heat transfer oil and steam, etc. were collected and stored in a computer. In case of no clouding, the distillation process was successfully completed since the temperature of heat transfer oil easily increased to 123 °C without needing auxiliary electrical heating. In case of clouding, the electrical heater was switched on in the later period of distillation process. When solar radiation was not concentrated, the temperature of heat transfer oil increased only to 95 °C and the distillation water had to be boiled by electrical heating. The overall thermal efficiency of solar CPCs ranged from 27.9% to 34.3%.