José J. Segovia

Phase equilibrium properties of binary and ternary systems containing tert-amylmethyl ether (TAME) as oxygenate additive and gasoline substitution hydrocarbons at 313.15 K

Abstract Experimental isothermal P – x – y data for the binary systems ( tert -amylmethyl ether (TAME)+the hydrocarbons n -heptane, cyclohexane, benzene and 1-hexene) and the ternary system ( tert -amylmethyl ether (TAME)+1-hexene+cyclohexane) at 313.15 K are reported. Data reduction by Barkers method provides correlations for G E using the Margules equation for the binary systems and the Wohl expansion for the ternary system. Wilson, NRTL and UNIQUAC models have been applied successfully to both the binary and the ternary systems presented here and they have been used for predicting the behaviour of the other ternary systems involving TAME+hydrocarbon+hydrocarbon, where the four types of substitution hydrocarbons have been used.

Experimental investigation of the vapor–liquid equilibrium at 313.15 K of the ternary system tert-amylmethyl ether (TAME)+n-heptane+methanol

Abstract Experimental isothermal P–x data at 313.15 K for the ternary system (tert-amylmethyl ether (TAME)+n-heptane+methanol) and for one of the unmeasured constituent binary systems, (tert-amylmethyl ether (TAME)+methanol) are reported. Data reduction by Barkers method provides correlations for gE using the Margules equation for the binary systems and the Wohl expansion for the ternary system. Wilson, NRTL and UNIQUAC models have been applied successfully to both the binary and the ternary systems. The presence of azeotropes in the ternary system and constituent binaries are studied as well as the presence of immiscible zones.

Progress towards an acoustic determination of the Boltzmann constant at CEM-UVa

An acoustic gas thermometer was used to achieve a determination of the Boltzmann constant, kB, using a misaligned stainless steel (316L) spherical cavity with an internal volume of approximately 268 cm3. Measurements of the speed of sound while the cavity is filled with argon at the temperature of the triple point of water, 273.16 K, and at different pressures between 78.2 kPa and 0.9 MPa, were used to extrapolate the value of the speed of sound in argon at zero pressure. The internal volume of the resonator was accurately determined by measuring microwave resonance frequencies at the same temperature and pressure conditions as for the acoustic measurements. The measurements were taken at pressures from 78.2 kPa up to 901.3 kPa, and at 273.16 K. As the results of the measurements, we determined kB = (1.380 644 1   ±   0.000 022 1)  ×  10−23 J K−1 which means a relative standard uncertainty of 16 parts in 106.

Uncertainty calculation of the effective emissivity of cylinder-conical blackbody cavities

A numerical and geometrical model for calculating the local effective emissivity of isothermal blackbody cylinder-conical cavities with lid, assuming diffuse reflection, is described. This has been developed by generalizing previous models based on conical and cylindrical geometries. The model has been validated by determining the diffusely reflected photon trajectories and the corresponding experimental view factors between given pairs of surface elements. Differences compared to theoretical values, were subsequently analyzed in terms of the models intrinsic uncertainty. A well-defined numerical function that calculates the effective emissivity as a function of its natural variables, intrinsic emissivity and geometrical parameters, is established. In order to calculate the probability distribution of the output quantity, we use the Monte Carlo method for the propagation of the probability distributions that characterize our knowledge concerning the values of the influence variables. The model is applied to heat-pipe black bodies installed at our laboratory, previously characterized at the PTB. A comparison with published uncertainty results, obtained by applying classical uncertainty propagation techniques, is also made.