High-Pressure Physicochemical Properties of Ethyl Caprylate and Ethyl Caprate

Abstract

The components of biodiesel derived from coconut oil or babassu oil such as ethyl caprylate and ethyl caprate are studied. The experimental speeds of sound in ethyl caprylate were reported at p = (0.1 to 101.32) MPa and at T = (292.90 to 318.32) K and in ethyl caprate at p = (0.1 to 101.32) MPa and at T = (292.90 to 318.28) K together with the experimental densities at 0.1 MPa for ethyl caprylate at T = (278.15 to 358.15) K and for ethyl caprate at T = (283.15 to 353.14) K as well as heat capacities were reported at 0.1 MPa for ethyl caprylate at T = (285.01 to 343.78) K and for ethyl caprate at T = (286.16 to 341.11) K. The density, adiabatic and isothermal compressibilities, heat capacity, isobaric thermal expansion, and internal pressure at elevated pressures and temperatures were calculated from the experimental results in the way described by Davis and Gordon (J. Chem. Phys. 1967Phys. , 46, 2650Phys. −2660 with the aim of studying the effect of changing of the carbon chain length from ethyl caprylate to ethyl caprate on pressure and temperature dependence of above-mentioned properties. Moreover, densities of ethyl caprylate and ethyl caprate were compared with densities of ethyl laurate and ethyl myristate to improve intersection of their isotherms.

Heat capacities of fatty acid methyl esters from 300 K to 380 K and up to 4.25 MPa

“…7. We can observed that the trends of the isobaric molar heat capacities of methyl caprate and methyl laurate with the variation of temperature are also almost the same, which is consistent with the conclusion obtained by Pauly et al [10] for the liquid isobaric molar heat capacities of fatty acid methyl esters at atmospheric pressure. Therefore, we can conclude that the number of carbon atoms in fatty acid group before the ester group has a significant effect on the isobaric molar heat capacities of fatty acid methyl esters, but it has a slight effect on …”

“…Fig. 3 shows the deviations between the experimental data in our work and those reported by Van Bommel et al [8] and Pauly et al [10] for the isobaric molar heat capacities of methyl caprate and methyl laurate at atmospheric pressure. It can be observed that our experimental results are consistent with those in literatures, showing a maximum absolute relative deviation of 1.2%.…”

“…Heat capacities of fatty acid alkyl esters are required for establishing enthalpy balances and the development of thermodynamic models for biodiesels [5,6]. To the best of our knowledge, there are only five sets experimental data for the heat capacities of fatty acid alkyl esters which have more than 8 carbon atoms in the fatty acid group: Deshpande et al [7] reported the heat capacity of methyl tetracaprate at 298 K; Van Bommel et al [8] reported the molar heat capacities of 13 fatty acid methyl esters from 5 K to 350 K; Zaitsau et al [9] reported the molar heat capacities of ethyl caprate from 5 K to 370 K; Pauly et al [10] reported the molar heat capacities of 7 saturated fatty acid methyl esters and 5 unsaturated fatty acid methyl esters from 250 K to 390 K; Dzida et al [11,12] reported the molar heat capacities of ethyl octanoate, ethyl caprate, ethyl laurate and ethyl tetracaprate from 285 K to 343 K. These experimental data are all measured at atmospheric pressure. For the isobaric heat capacities of methyl or ethyl esters of fatty acids at high pressure, no experimental data were reported, only Dzida et al [10,11,13] to 380 K and at pressures from 0.1 MPa to 4.25 MPa were measured with a flow calorimeter.…”

Developing an Extreme Learning Machine-Based Model for Estimating the Isothermal Compressibility of Biodiesel

“…Various types of long-chain fatty acids can be found in fatty feedstocks from which biodiesel can be obtained, resulting in different molecular structures of fatty acid esters in biodiesel. Different thermophysical characteristics result from various molecular structures, which impact the fuel performance, the exhaust gas content, and combustion efficacy in diesel engines [9][10][11].…”

Viscosity of oxygenated fuel: A model based on Eyring’s absolute rate theory

“…Furthermore, the addition of oxygenated fuels will affect thermophysical properties of diesel. So the study on thermophysical and transport properties of oxygenated fuels is required for a better understanding and improvement in engines [9], which include heat capacity [10], critical properties [11] and speed of sound [12], etc. Viscosity has a significant impact on the spray characteristics and combustion of the fuel [13].…”