modelling

Economic and polyvalent, numerical simulation, or computational fluid dynamics (CFD) lends itself to the topic of air diffusion. An overview of this useful modelling strategy.

The article presents a zonal model called Sim_Zonal which can be used to predict air movement, temperature distribution and comfort characteristics in a room. The model is based on an approximate partitioning of the room, which is divided into a small number of 'cells', usually in the order of 10 to 100, as compared to 10000 or more for typical CFD calculations. Exchanges are calculated between the cells when mass balance and heat balance equations are applied. Empirical laws describe airflow where plumes or jets occur.

Among significant occupational health problems are building-related health complaints and symptoms. A potential cause has been identified as the elevated concentrations of various types of indoor contaminants, which are frequently associated with inadequate ventilation. This research aimed to model and evaluate the performance of several ventilation methods on volatile organic compound (VOC) removal in indoor environments. The time history of the contaminant concentrations in a model office have been simulated using a newly developed computer model.

Included in applications of multizone airflow and contaminant dispersion models to specific buildings are air quality diagnosis, weatherization, smoke control, and pressure balancing for laboratory hood safety. States that uncertainties in model inputs mean that the benefits of these applications are not being fully realized. Emphasises the need for an economical test method that is as accurate but less intrusive and faster than incremental or component-by-component blower door testing.

Describes an improved form of the standard k-epsilon model for buoyant room flows and gives an assessment of the results. The improved model is based on the generalized gradient diffusion hypothesis of Daly and Harlow. Compares the results from the computations for three-dimensional flow with temperature measurement performed by the authors in a laboratory room with displacement ventilation. A good agreement is shown by the numerical results, better than the results from the standard model.

Residential apartments in Hong Kong are usually equipped with up to three window-type air conditioners, placed in living rooms and bedrooms, operated over seven months of hot and humid weather. Analyses the arrangement of room furniture to minimise cold air draughts. The performances were modelled using FLOVENT.

Heat transfer in loose-fill attic insulation was investigated in a large-scale model of a ventilated attic built in a climatic chamber. The particular aspect of this study was heat transfer by convection and its effect on heat losses through the attic floor. It was shown by thermal resistance measurements that the measured and calculated thermal resistance of the attic floor is within the margin of error. Air movements were detected in the insulation, sufficient to cause a decrease in the thermal resistance of the attic floor.

In order to determine whether high outdoor ozone concentrations are transferred to the indoor climate of museums, a monitoring project was carried out on eleven museums, art galleries, historical houses and a museum library for 38 days over the summers of 1984 and 1985. The differences in indoor ozone levels between the buildings could be explained by differences in building and ventilation system design, and this was verified by a mathematical model. Peak indoor ozone levels were highest in building with no air conditioning but a high rate of air exchange with the outdoors.

A model-based technique is described to raise the level of sophistication of building automation systems (BAS). Models are derived using stochastic multivariable identification, and describe the behaviour of air temperature and relative humidity in a full-scale office zone equipped with a dedicated heating, ventilating and air conditioning plant. The models give good accuracy. Investigates the usefulness of the models for facilities management. The 'temperature' model demonstrated substantial improvement of temperature regulation and reduction of energy consumption.

Ventilation effectiveness is an important means to describe and evaluate the performance of a ventilation system. In terms of ventilation tasks, this paper presents a unified physical model for the ventilation efficiency scales based on conservation principles to which a ventilation system should conform. Transport equations for the local mean age of air and contaminant are respectively obtained, which can be integrated solved by the CFD program. To validate the proposed model and CFD simulation of the ventilation efficiency, a 2-D laminar ventilation flow is analysed.