English

The performance of an exterior hood is known to be affected by the cross draft (1, 2). Based on the knowledge from a classical "Rankin's nose" or "semi-infinite body" problem, in which the opening shrinks to a sink instead of a finite opening, the exhausted airflow combining the cross draft forms a capture envelope in front of the hood(3). All streamlines within the envelope lead to the hood opening, those outside of the envelope lead to infinity. Therefore, contaminant released inside the envelope tends to be captured by the hood; otherwise, it tends to escape beyond capture.

When designing push-pull ventilation system as usual, it has been considered that supply airflow should be thoroughly exhausted by suction inlet. However, an escape of some of the supply airflow from an exhaust inlet could be permitted in the push-pull ventilation system, if all of the contaminants transported to the exhaust inlet do not escape and can be exhausted. In this study, we investigate appropriate flow rate for push-pull ventilation system by using CFD techniques.

This study is a part of a research project called 'Convective Flows and Vertical Temperature Gradient within Active Displacement Air Distribution'. The project and the two zone model developed have been introduced by Sandberg (1). The aim of this study was to examine the ventilation effectiveness with different elevations and horizontal positions of the heat sources within active displacement air distribution. This was studied by carrying out experiments using convective heaters and ordinary fluorescent tube lamps at several elevations as heat sources.

Productivity is one of the most important factors affecting the overall performance of any organization. Productivity is defined as the ratio output divided by the input used to produce the output. The output refers to products and services produced by an organization (2). Increased attention has been paid to the relationship between the work environment and productivity in the 1990s. Laboratory and field studies show that the air quality and thermal conditions at work may have a notable impact on the performance of the occupants, and consequently on labor productivity (1,3,4).