AIVC - Air Infiltration and Ventilation Centre

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mathematical modelling

Modeling particle deposition on HVAC heat exchangers

LBNL - Proceedings of Indoor Air 2002 (9th International Conference on Indoor Air Quality and Climate) - June 30 - July 5, 2002 - Monterey, California - vol 1, pp 521-526, 3 figs, 10 refs","This paper presents a model for particle deposition on fin-and-tube heat exchangers, that takes into account mechanisms such as impaction, diffusion, gravitational settling and turbulence. Models results are presented and analysed. They agree with experimental data.

Calculation of the room velocity using kinetic energy balance

For a long time, scientific research has tried to establish the relationships between jet momentum and room velocities. The final breakthrough is still to come. One approach is to use a kinetic energy balance, which was initially suggested by Elterman (1980). This paper presents a thorough kinetic energy analysis. Based on the analysis, a new method is developed for calculating the average room velocity. The calculation method is evaluated with the experimental date from laboratory experiments with three different air distribution methods.

Numerical and experimental studies on room airflow

In this study, the air flow in a small scale industrial hall is simulated numerically using two different computing codes, the commercial flow solver with a high-Reyholds number turbulence model and a university code with a low-Reynolds number turbulence model. The results are compared with measurements. Two different air supply arrangements with grille or nozzle types of air terminal devices are studied, both with isothermal and non-isothermal boundary conditions.

Automatically generated zonal models for building air flow simulation: principles and applications

Starting from models library, a zonal model of an entire building can be constructed by assembling the appropriate modules. A model-generating tool called GenSPARK makes the process automatic. This paper describes how that tool works and give examples of configurations that can be analyzed.

On the natural displacement flow through a full-scale enclosure, and the importance of the radiative participation of the water vapour content of the ambient air

Experiments were operated to determine the thermal stratification in a full-scale enclosure with natural ventilation driven by thermal source. Results provided by various predictive techniques were compared with experimental data. The salt-bath modelling technique and related mathematical model of Linden appear to be unappropriate for this type of air flow. CFD gives realistic predictions, especially when using a complete thermal radiation model.

Prediction of indoor gaseous pollutant dispersion by nesting sub-zones within a multizone model

A zonal model has been nested within a multizone model to allow increased resolution in the prediction of local air flow velocities, temperature and concentration distributions between and within rooms. Simulations from the new program have been compared with measurements and results from other models.

A simplified system for indoor airflow simulation

This paper presents a simplified system based on a new air supply opening model along with a numerical method to accelerate and simplify the convergence procedure of predicting air distribution in ventilated rooms. The new numerical method is called error pre-treatment method. It is simpler than multi-grid method and effective for SIMPLE algorithm commonly used for indoor airflow simulation.

Predicting the pressure coefficients in a naturally ventilated test room using artificial neural networks

In this paper, the objective of the authors is to investigate the use of artificial neural networks for the prediction of air pressure coefficients across the openings in a light weight single-sided naturally ventilated test room.

Simplified modeling of cross-ventilation airflow

A simplified model for room cross-ventilation airflow has been developed using scaling analysis,experimental correlations and computational fluid dynamics. The model considers the main jet region and the recirculations region and leads to a set of formulas that predict the airflow rates and characteristic velocities in these two regions. Examples of application of the model to cross-ventilation design are presented.

Simplified numerical models for complex air supply diffusers

From experimental data on eight common air diffusers, authors developed simplified methods (the box method and the momentum method) to describe air flow and temperatures in the air jet that can be used as imput data for room air flow CFD calculations. The box method is appropriate for most of the diffusers. The momentum method gives good results for five diffusers. As it is simpler, authors recommend that it is used whenever applicable.