English

The INBEMI (Instituto de Beneficio de Minerales) is a Research Institute of the National University of Salta, working on the areas of mineral processing and extractive metallurgy. At present, the INBEMI is mainly working in the field of boron industry using borates as raw material. The main borate deposits in Argentina are in the northwestern provinces, near the borders with Chile and Bolivia. Among the research studies an important place is given to the industrial ventilation, including the control of the air quality that is discharged to the external atmosphere.

The rotating vane anemometer is an instrument that is widely used in the field by maintenance engineers and inspectors. The anemometer consists of a vane that is held at right angles to an airflow. In modem instruments the speed of rotation of the vane is sensed and measured electronically and the air speed, which is a function of the speed of rotation of the vane, is indicated on a meter.

For the calculation of velocities in air-jets behind the ventilating outlets, the constants of ventilating outlets must be known. These constants are specified for each type of ventilating outlets experimentally. They can be usually defined from measured behaviours of axis velocities in the main area of jet, which demands to measure velocity profiles in cross flow section, in several distances from the outlet. The constants of ventilating outlets can be also defined from the air-jet extension in the main jet area behind the ventilating outlet.

Unexpectedly, the indoor-outdoor pressure difference did not affect significantly the moisture content in different layers of two outer walls but the moisture content depended more strongly on the moisture content in outdoor.

When designing the outlets for the ventilation or hot-air heating of particular spaces, we meet usually the problems to specify a form and reach of the air jet and a distribution of velocities and temperatures in the space followed. In practice the calculations of nonisothermal air jets are made using a number of calculation relations to be found e.g. in lit. (1) and other. But when applying the analogical relations derived by different authors we can find out considerable differences in results.

The influence of the electrostatic forces on airborne particles have been known for centuries. These early discoveries have been summarized in several publications including the classical book "Electrostatic Precipitation" by White (1) and many others (e.g. 2, 3, 4). The utilization of the electrostatic force led to the development of electrostatic precipitator (ESP) which has been used for pollution control purposes since the beginning of this century. An excellent historical review about the development of electrostatic gas cleaning has been presented by White (1).

The exterior hood has been used extensively in the local exhaust devices to capture a variety of contaminants generated in a working-site. The performance of a hood can be measured by either how well it captures the contaminants or how far away it can perform an effective capture. It has been known theoretically that in the presence of an uniform cross draft a capture envelope will form in front of an exhausted opening(2, 3). All streamlines inside an envelope will lead into the opening; otherwise, those outside the envelope will lead to infinity downstream.