Development of a measuring system for the volatilization characteristics of essential oils and evaluation of the measured data by advection–diffusion simulation

• Published in: Japan Journal of Aromatherapy Vol. 26; no. 1; pp. 1 - 9
• Main Authors: ZHANG, Hongye, TOGASHI, Shigenori, MIYAKE, Ryo
• Format: Journal Article
• Language: Japanese
• Published: Aroma Environment Association of Japan 07.02.2025; 公益社団法人 日本アロマ環境協会
• Subjects: essential oils; gas sensor; simulation; vapor pressure; volatilization; シミュレーション; 揮発; 気体センサ; 精油; 蒸気圧
• ISSN: 1346-3748; 2189-5147
• DOI: 10.15035/aeaj.260101

From the point of view of remembering the scent of the essential oils, this study builds a volatilization characteristics map by considering vapor pressure. In this study, we developed a measuring system with two gas sensors to examine the volatilization characteristics of essential oils. The first and second gas sensors were set at distances of 15 and 30 mm, respectively, from the essential oil reservoir in the measuring tube. The measuring system was housed in a transparent case to eliminate the influence of external air fluctuations. A trial experiment was conducted for 60 s using Lavandula angustifolia to evaluate the measuring system. Three feature indicators were extracted: the upward gradient ratio of the first and second sensor signals, the maximum value of the first sensor signal, and the residual rate of the first sensor signal. We plotted a volatilization characteristics map with the upward gradient ratio of the first and second sensor signals on the horizontal axis and the maximum value of the first sensor signal on the vertical axis. Moreover, an advection–diffusion simulation was conducted to clarify the relationship between the volatilization characteristics map and the vapor pressure. The following conclusions were drawn from the simulation results: Advection–diffusion with a high velocity, that is, the essential oils with a high vapor pressure, were distributed on the upper side of the volatilization characteristics map. In contrast, the essential oils with a low vapor pressure were distributed on the lower side of the volatilization characteristics map. In addition, the gradient ratio of the first and second sensor signals changed with the vapor pressure and the content of the delayed scent that follows the initial scent. That is, a lower vapor pressure or a larger delayed scent content resulted in a more right-side in the volatilization characteristics map.