Abstract
The specific heat capacities of some triglycerides commonly found in palm oil were determined with a heat-flux differential scanning calorimeter. The specific heat capacity measurements were made under the optimum operating conditions determined earlier: scan rate 17 deg·min−1, sample mass 21 mg and purge gas (nitrogen) flow rate 50 ml/min. Pure triglycerides (four simple and four mixed) were used in the experiments. The four simple triglycerides were trilaurin, trimyristin, tripalmitin and tristearin, and the mixed triglycerides were 1,2-dimyristoyl-3-oleoyl, 1,2-dimyristoyl-3-palmitoyl, 1,2-dipalmitoyl-3-oleoyl and 1,2-dioleoyl-3-palmitoyl. The results of this study are compared with literature values and also with values obtained by using estimation methods. The experimental specific heat capacities are within ±1% precision with a 95% confidence level.
Zusammenfassung
Mittels eines Wärmefluß-Differential-Scanningkalorimeters wurde die spezifische Wärmekapazität einiger, für gewöhnlich in palmöl vorkommender Triglyceride bestimmt. Die Messungen der spezifischen Wärmekapazität wurden unter den bereits zuvor ermittelten optimalen Versuchsbedingungen durchgeführt: Scangeschwindigkeit 17 deg/min, Probenmasse 21 mg und Spülgasgeschwindigkeit (Stickstoff) 50 mL/min. In den Experimenten wurden reine Triglyceride (vier einfache und vier gemischte) verwendet. Die vier einfachen Triglyceride waren Trilaurin, Trimyristin, Tripalmitin und Tristearin, die gemischten, Triglyceride waren 1,2-Dimyristol-3-oleyyl, 1,2-Dimyristol-3-palmitoyl, 1,2-Dipalmitoyl- 3-oleoyl und 1,2-Dioleoyl-3-palmitoyl. Die Ergebnisse dieser Untersuchung wurden mit Literaturwerten und auch mit Werten verglichen, die anhand von Schätzungsmethoden erhalten wurden. Die experimentellen spezifischen Wärmekapazitäten lagen bei einem Konfidenzintervall von 95% innerhalb von 1%.
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Abbreviations
- C :
-
carbon number, e. g. C36 indicates a carbon number of 36
- C p :
-
specific heat capacity at constant pressure, J·g−1·deg−1
- C v :
-
specific heat capacity at constant volume, J·mol−1·deg−1
- C ov :
-
ideal specific heat capacity at constant volume, J·mol−1·deg−1
- MMO:
-
1,2-dimyristoyl-3-oleoyl, a triglyceride
- MMP:
-
1,2-dimyristoyl-3-palmitoyl, a triglyceride
- OOP:
-
1,2-dioleoyl-3-palmitoyl, a triglyceride
- P :
-
pressure
- PPO:
-
1,2-dipalmitoyl-3-oleoyl, a triglyceride
- T :
-
temperature, °C
- T m :
-
melting point, °C Gree letters
- α:
-
the unstable phase in the triglyceride
- β:
-
the most stable phase in the triglyceride polymorph
- β′:
-
the most unstable phase and intermediate phase in the triglyceride polymorph
- r * :
-
reduced density used the estimation method of Bondi (1968)
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Morad, N.A., Idrees, M. & Hasan, A.A. Specific heat capacities of pure triglycerides by heat-flux differential scanning calorimetry. Journal of Thermal Analysis 45, 1449–1461 (1995). https://doi.org/10.1007/BF02547438
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DOI: https://doi.org/10.1007/BF02547438