Theoretical and experimental investigation of impinging jet ventilation and comparison with wall displacement ventilation.

Experimental data for an impinging jet in a room are presented in this paper and non-dimensional expressions for the decay of maximum velocity over the floor are derived. The performance of that system is compared with the one of a wall displacement ventilation.

Validation of a CFD model for temperature and particulate concentration in a test room with mixed air and displacement ventilation

This study aims to validate a CFD model (Flovent) for calculation of temperature and particulate concentration in a ventilated room. Measurements were operated in a test room with a heat source and a cigarette source. Good agreement was found with the model for temperatures with a mixed ventilation system in the room as well as with a displacement ventilation system. For particulate concentrations, the model was validated for mixed ventilation and 'borderline validated' with displacement ventilation.

Design methods and evaluation of thermal comfort for mixing and displacement ventilation

Measurements are made first in a full-scale room ventilated with a mixing ventilation, and later with a displacement ventilation. A new method to design mixing ventilation is established. A comparison shows the thermal comfort obtained with the two systems.

Jet drop and draft risk in a mixing ventilation office : experimental and numerical investigations

This paper is a presentation of a theoretical and experimental analysis of supply air jet flow patterns in a mixing ventilation system. Investigation procedure aims at reducing draft risks.

Displacement ventilation versus mixing ventilation - comparison of energy use.

There are basically two ventilation principles that can be utilised in a room: mixing ventilation (denoted MV) and displacement ventilation (denoted DV). In MV, air with high velocity is supplied outside the zone of occupancy, which ideally gives uniform temperature and concentration in the room. In DV, cool air with low velocity is supplied in the lower part of the room. Contaminated air and heat is transported towards the ceiling by the convection currents set up by heat sources, where is is extracted.

Air distribution in a room and design considerations of mixing ventilation by flow elements.

The paper shows detailed measurement of the air distribution in a room ventilated by mixing ventilation according to the specifications given by the International Energy Agency work. (Energy Conservation in Buildings and Community Systems programme, Annex 20). It describes a number of flow elements and how they are used as design tools. The flow elements are the throw of an isothermal jet and the change in jet velocity when the jet moves from the upper to the lower part of the room. A third flow element is the penetration length of a non-isothermal wall jet.

Internal partitioning and air movement in mixing ventilation.

In this study, the effects of internal partition on ventilation performance in terms of room air change efficiency and ventilation effectiveness were investigated. A model test room was used and the physical test conditions were simulated numerically by using a CFD (Computational Fluid Dynamics) code under isothermal conditions. The test room was ventilated in mixing mode and different partition configurations, including its location, height and gap underneath as well as the contaminant source location, were examined.

Concentration distribution in a mixing ventilated room.

Today there is an increasing focus on the importance of a proper ventilation system to obtain good working conditions in the term of air and thermal quality to ensure high productivity. Different ventilation principles are used, e.g., mixing ventilation and displacement ventilation. In order to ensure that the ventilation system meets the demands it is important to know which parameters that influence the performance of the system. In this work the mixing ventilation principle was investigated.

Personal exposure between people in a mixing ventilated room.

Due to the fact that more and more people are spending a considerable amount of time in an indoor environment it is important to minimise (or control) the amount of pollution that a person is exposed to. Sources of indoor air pollution are building materials, furniture, equipment and people. This work concentrates on personal exposure in a mixing ventilated room. The aim of this work is to investigate the exposure of a person due to pollution from another person in a mixing ventilated room.

A CFD study of airflow in a mixing box.