Predictions of transfer phenomena in dispersed phases which are based on single particle behaviour are limited in applicability because they do not consider the interaction between particles themselves and with the surrounding fluid. A theoretical analysis is presented in this paper which describes fluid entrainment by a single stream of droplets and the effect of this boundary layer flow on subsequent drop motion. The predicted effects are compared with experimental measurements of droplet velocities in streams moving through gaseous and liquid environments.

---

Using a flow visualisation technique, hot wire anemometer and Kiel probe measurements, air flow characteristics of a model air-cooled heat exchanger have been studied. With box type plenum chambers the results indicate that a central core of rotating air exists with large areas of recirculating flow below the reattachment points particularly in the corners.

---

The separation of liquid mixtures by thermal diffusion has been regarded as uneconomical in comparison with other more conventional separation processes due to the high energy costs predicted by the available design equations. As a result, the applications of the technique have been essentially limited to laboratory operations as an analytical-tool or in preparativescale purifications.

---

Two cylinder termogravitational columns have been used to study the behaviour of several liquid binary mixtures under the action of a horizontal temperature gradient. It has been found that the relation between the solubility parameters, the molecular weights and the normal boiling points of the components gives no indication as to the component concentrating in each extremity of the column, at steady state. For all but two of the liquid pairs studied the component with the higher density concentrates at the bottom of the column. Some separation data on twenty-six binary systems are presented.

---

Discutem-se os objectivos a atingir na formação do engenheiro químico por uma análise dos campos de actividade e funções que definem a profissão. Procura-se, seguidamente, avaliar a importância de certos aspectos relevantes na formação, como o treino profissional, educação permanente e especialização, perspectivando-os em contexto universitário e nacional

---