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Pressure-density-temperature data (10 655 data points) in the gas and liquid homogeneous phases and in the bulk zone are reported for 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea). The measurements have been performed with a vibrating tube densimeter over 12 isotherms at temperatures between 253 K and 403 K and pressures up to 20 MPa. The uncertainties of temperature and density measurements are less than 0.02 K and 0.1 kg m -3 , respectively. The uncertainty on the pressure values is less than 2 × 10 2 Pa in the vapor phase and less than 2 × 10 3 Pa in the compressed liquid phase. A correlation for saturated liquid density has been developed from the present data. Furthermore, a comparison is made between experimental data and a semipredictive density model.

Modelling and control of chemical process systems are usual applications of artificial neural networks that have been explored so far with success. This paper deals with the potential application of neural networks to the multivariable control of a solvent extraction pilot plant. The pilot plant to be controlled is a pulsed liquid-liquid extraction column, which presents a non-linear behaviour and timevarying dynamics. Previous works have shown that the column could be maintained in its optimal behaviour by means of the control of conductivity by action on the pulse frequency. A given product specification can be obtained by the control of the product concentration in the outlet stream by acting on the solvent feed-flow rate. Owing to interactions between one variable and the other, a two inputtwo output control scheme has been developed and implemented. Promising experimental results have been obtained by using neural networks as an alternative tool for online control of chemical plant with dynamic changes.

In microfluidics, flows are laminar due to low Reynolds number (<1). Consequently, mixing between two liquids is mainly obtained by natural diffusion which may take a long time or equivalently requires centimetre length channels. However, it is possible to generate chaotic-like flows either by modifying the channel geometry or by creating an external perturbation of the flow. In this paper, an active micromixer is presented consisting on thermal actuation with heating resistors. In order to disturb the liquid flow, an oscillating transverse flow is generated by heating the liquid. Depending on the value of boiling point, either bubble expansion or volumetric dilatation controlled the transverse flow amplitude. The configuration is identical to the one of Dodge et al. [7], but the transversal oscillating flow is created by thermal actuation instead of pneumatic ones. A chaotic like mixing is then induced under particular conditions depending on volume expansion, liquid velocity, frequency of actuation… This solution presents the advantage to achieve mixing in a very short time (1 s) and along a short channel distance (channel width). It can also be integrated in a more complex device due to actuator integration with microfluidics.

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