Highly accurate photopyroelectric measurement of thermal diffusivity of vegetable oils
✍ Scribed by Dorin Dadarlat; Camelia Neamtu; Mihaela Streza; Carmen Socaciu; Constantin Bele; Francisc Dulf
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 390 KB
- Volume
- 111
- Category
- Article
- ISSN
- 1438-7697
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✦ Synopsis
Abstract
High‐accuracy photopyroelectric measurements, in the thermal‐wave‐resonator‐cavity configuration, were performed in order to measure the thermal diffusivity of some vegetable oils. The high resolution (relative error ±0.5%) of the above method allows for the detection of small changes in the values of this dynamic thermal parameter. The accuracy of the results is mainly due to the possibility to precisely control the variation (30‐nm step) of sample thickness, a proper selection of the range of the thickness scan (2 µ__~m~__ < L~m~ < 4 µ__~m~__ ˜ 5 µ__~m~__), and an iterative procedure of data analysis. A correlation between thermal diffusivity and the fatty acid composition (obtained via gas chromatography) is suggested for some fresh (sunflower, hemp, flax, and soybean) oils and for hemp oil exposed to a microwave field: Thermal diffusivity appears to be determined by the overall content of polyunsaturated fatty acids.