In this article, four turbulence models are studied to capture the flow and temperature behavior of the air close to a low-velocity diffuser for displacement ventilation. Turbulence is modeled by means of one zero-equation model and three different two-equation models, i.e. the LVEL, the RNG, the Standard k-e, and the Chen-Kim model. They are evaluated for their performance in predicting the air flow patterns and temperature profiles close to the diffuser.
Natural ventilation’s fluctuating airflow has impacts on the thermal comfort and VOCs transportation in the naturally ventilated buildings. Research about the fluctuating characteristics of the airflow in naturally ventilated buildings was carried on in t
This study was aimed to analyse the ventilation efficiency and indoor air quality in the conventional kitchens, when porous screens were installed on the transoms. Numerical simulations and laboratory full-scale experiments were carried out in the model kitchen in the Department of Architecture at National Cheng-Kung University. The influences of porous screens on the temperature fields, flow structures and ventilation rates were indicated. The "Tracer-gas Concentration Decay" method was conducted to measure the air exchange rate and the age of air in the model kitchen.
Numerical simulation (CFD code) was used to optimise the design of the ventilation system of a large underground bus terminal complex near Seoul (Korea). The analysis of air flow patterns and parameters such as NOx and CO concentrations (from diesel engines of 19 buses) allowed to suggest and study modifications of design (change in airflow rates and grilles locations). Changes improve indoor air quality as the mean residual life time of contaminated air decreases.
Difficulties of CFD calculations to predict comfort especially in case of high level of turbulences are enquired in this study. Statistical corrections when the direction of the velocity vector changes are proposed to improve CFD models.
A Norwegian research project in under progress to develop a new concept for control of air movements in protection isolates, operating theatres and other risk areas in hospitals. The aim is to reduce airborne hospital infections through appropriate design of building, HVAC installation and control of air movements. A container solution was developped for isolates. Its HVAC system, and especially the ventilation system are described in details. The first container has been finished in June 2002 to be tested.
Design of thermal and air environment for large spaces is often realised with CFD simulations but due to measurement difficulty there are few cases in which results are compared after construction. This study uses a simple method for visualizing air currents and for estimating distribution of air movements with balloons.
CFD simulations and measurements were used in isothermal air-conditioned space of a gymnasium. Different airflow patterns due to different supply air were simulated. Results obtained are correct considering the complexity of boundary conditions.
The study characterised the mixing of tracer gas in three ventilation systems with two different airflow rates (totally outdoor air).The test procedure is presented and errors are calculated and compared.
The study examines the effect of diffuser, buoyancy and surface radiation on flow, in order to better understand the changes in room air flow due to the energy control strategy. Calculations have been applied on one room for two different ceiling air diffusers.
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