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Liquid-liquid equilibria (LLE) of alkane þ aromatic þ solvent systems is of interest in connection with the extraction of aromatics from petroleum fractions, for example, naphtha, distillates, lube oil, and so forth. Though the actual industrial systems contain a large number of compounds, LLE studies on a smaller number of representative compounds are also important in the development of theoretical/semiempirical LLE models for use in the design of extraction processes. In the present work LLE data has been experimentally obtained for the ternary systems heptane þ benzene þ furan-2-carbaldehyde (furfural) and heptane þ methylbenzene (toluene) þ furfural at two temperatures (298.15 and 303.15) K, and for the quaternary systems heptane þ dodecane þ benzene or toluene þ furfural at 298.15 K. The data are seen to be correlated excellently by the nonrandom two-liquid model. The model parameters were determined by data regression using the Nelder-Mead optimization technique. The model also enabled tie line calculations between the last experimental tie line and the plait point, thereby giving the shape of the full two-phase region.

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Determination of aspect ratio distribution is important for elongated, needle-shaped particles whose utility and/or value may depend on this feature. In this work rice grain is taken as an example of such a particle and its aspect ratio distribution in various samples is found using image processing. The samples examined were from three different grades (commonly termed as full, half and broken) sold in local market and priced according to their size. From the analysis, reference aspect ratios were assigned to classify the grains and hence determine the extent of off-size in each market grade. Further, the effectiveness of the technique to quantify mixed or adulterated grades was studied. It was found that it is possible to know the undesired content within 10 percent accuracy.

Measurements for developing turbulent flow in a high aspect ratio (AS = 6), small area ratio (AR = 2), 90 deg curved diffuser have been made. Mean velocities, static and total pressures, and turbulence intensities were measured using a three-hole pressure probe and a hot-wire probe. Flow visualization studies were also made using a tuft probe. Experiments show that, except for a very small zone near the exit, there is no flow reversal in any part of the diffuser. Streamwise bulk flow is seen to shift toward the concave wall side in the downstream half of the diffuser, under the influence of centrifugal force. One pair of counter-rotating vortical motion was identified at 30 deg turn, which break into more pairs (at least two) of counter-rotating vortices in the downstream. The z-plane velocity profiles show a nearly 2-D flow in the initial part of the diffuser but subsequently the flow becomes increasingly 3-D. A static pressure recovery coefficient of 51 percent was achieved.

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