Estimation of the sharma constant and thermoacoustic properties of vegetable oils

Abstract

The density and volume of four Indian edible vegetable oils, sunflower, rice bran, groundnut and coconut, and one Indian nonedible oil, castor oil, have been experimentally determined. The values obtained were used to estimate the volume expansivity a, hence the thermoacoustic parameters, such as the Sharma constant S~ the isochoric temperature coefficient of internal pressure ~] v, the isochoric temperature coefficient of volume expansion Jr, reduced volume I~, reduced compressibility ~ and the Huggins parameter F. The results obtained show that the Sharma constant So has the same characteristic value of 1.11 ___ 0.01 for the five oils, thus establishing the constancy of the Sharma parameter. All the other parameters are of the expected order of magnitude; however, in all cases there is a uniform deviation at 293~ which can be attributed to the behavior of density and volume at this temperature.KEY WORDS: Density, Huggins parameter, isochoric temperature coefficient of internal pressure, isochoric temperature coefficient of volume expansion, physicochemical properties, reduced compressibility, reduced volume, Sharma constant, vegetable oils, volume expansivity.

Volumetric properties of sunflower and olive oils at temperatures between 15 and 55 °C under pressures up to 350 MPa

“…Linoleic acid has a lower molar mass and degree of unsaturation than the oleic acid, a lower specific volume [17], and thus a lower contribution to the specific volume of SO than the oleic acid of OO. A quantitative comparison with previous measurements at atmospheric pressure [18][19][20] and extrapolated from high pressure [21] is illustrated in Figure 1. The values for the SO were close to those measured in [18] between −20 and +80 • C: the absolute difference was less than 9 × 10 −7 m 3 kg −1 below 20 • C and less than 7 × 10 −6 m 3 kg −1 above.…”

“…A quantitative comparison with previous measurements at atmospheric pressure [18][19][20] and extrapolated from high pressure [21] is illustrated in Figure 1. The values for the SO were close to those measured in [18] between −20 and +80 • C: the absolute difference was less than 9 × 10 −7 m 3 kg −1 below 20 • C and less than 7 × 10 −6 m 3 kg −1 above. The deviation with the data of [19] grew systematically with temperature, reaching 1 × 10 −5 m 3 kg −1 at 60 • C. For OO, the absolute difference with the data of [20] between 30 and 90 • C was not more than 4 × 10 −6 m 3 kg −1 and not more than 7 × 10 −7 m 3 kg −1 with the data of [21] between 30 and 60 • C. Deviations from the model could be attributed to slightly different compositions of the oils, to experimental uncertainties of each measuring methods (conventional dilatometer or pycnometer in the literature vs. oscillating U-tube in this work) and to a lower accuracy of temperature control.…”

“…An estimation of the thermal expansivity at atmospheric pressure has been given by Subramanyam [18] for SO, and a generalisation of vegetable oil properties by Coupland [23]. From their results, the thermal expansivity coarsely increases linearly with temperature at atmospheric pressure.…”

Density and viscosity of vegetable oils

“…Halvorsen et al state that the results of Equation 3 predict density data within an average absolute deviation of 0.14%, as compared to 0.16% for the Lund equation. Experimental liquid viscosity data have been shown to generally follow the well-known Andrade equation: [8] where η is the viscosity and T is the absolute temperature.…”

Estimation of sharma constant and thermoacoustic properties of fatty acids

“…In previous work (12), o~ was calculated from volume and density measurements as functions of temperature at intervals of 10 K. V 2 and V 1 are the molar volumes at temperature T 2 and T 1, respectively.…”