air distribution

Stratum ventilation (SV) is an energy-efficient solution to provide thermal comfort and improve air quality. The air distribution in rooms with SV depends on the room layout, location of supply and exhaust grills and indoor heat gains. Therefore, the commonly used methods to predict air temperatures in the occupied zone do not usually fit the indoor temperature distribution. At the same time, detailed simulations of indoor air distribution are still mainly used in complicated room layouts and research.

A smart ventilation system is able to continually adjust itself to provide the desired indoor air quality (IAQ) while minimizing energy use, utility bills, thermal discomfort and noise. A smart ventilation system is also responsive to e.g. occupancy, outdoor conditions, direct sensing of contaminants and can provide information about e.g. IAQ, energy use and the need for maintenance or repair. Technically, all components for such systems are available in the market.  

A literature review has revealed that there is a very limited number of numerical or experimental studies of the air flow for mechanically ventilated large occupied rooms. Existing literature suggests that a room with more than 5 meters floor-to-ceiling height can be considered as a large space. The aim of this paper is to present a set of detailed air temperature and velocity measurements in a large open plan office located in south England.

When planning ventilation systems for energy efficient housing, an appropriate design of the overflow elements between rooms is important as it influences ventilation losses, indoor air quality and sound attenuation between rooms. Based on calculation results of the natural in- or exfiltration rates through the building envelope as a function of the overflow element’s flow resistance, this work proposes a maximal pressure drop of 2-3Pa for overflow elements in energy efficient buildings.

On the basis of modelling with similarity theory and by using the Archimedes number, Ar, as the similitude parameter, this paper analyzes the air distribution of a busbar corridor in a hydropower station by using the Particle Image Velocimetry (PIV) measurement technique.

The aim of this study was to develop a simplified CFD model for the inlet jet of a swirl diffuser for the simulation of room airflow patterns. The swirl diffuser creates a complex flow pattern with high induction of room air, thus possessing a challenge for simulation. The studied diffuser was a model intended to be used in large enclosures. The flow pattern was adjustable between two basic modes: radial swirl jet for cooling conditions and compact downward swirl jet for heating conditions. For developing the CFD model, a series of laboratory measurements of the flow field was carried out.

This paper focuses on the performance of a new air curtain ventilation system. Particle Image Velocimetry (PIV) is used to visualize and investigate the airflow characteristic of an air curtain in an enclosure and the airflow pattern and temperature fields are measured and analyzed in detail. The air supply velocity and the slot inlet location were varied during the experimental process. The current results show that with the increase of air supply velocity the cooling effect in the occupied zone is further strengthened.

The air distribution characteristics formed by an "air curtain" ventilation approach are investigated in detail. The airflow visualization and full-scale experimental results of air distribution in an occupied zone are reported in this paper. The Coanda effect of air curtain ventilation and the spreading airflow over the floor in a room are demonstrated. Additionally, the "air lake" or "air pool" phenomenon created by air curtain ventilation resembles displaced air movement to some extent.

Nowadays, the ceiling slot diffuser is very popular in offices. However one of the problems, for the producer and designer of linear diffusers, is to determine and specify correctly the throw-length data, in order to achieve optimal air movement in the occupied zone. Here, experimental studies were conducted to identify the variation characteristics in jet behaviour for ceiling slot diffusers. Nine cases, covering different aspect ratios, were measured under isothermal conditions in two test rooms using traversing measurement systems.

This paper introduces a concept of robustness of an air distribution method, which is defined as being capable of meeting the ventilation requirements during varying operational conditions. The robustness performance may be particularly important when the system allows individual control of the supply air parameters. As a preliminary example, plenum-based (ductless) air distribution methods are studied using computational fluid dynamics.