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mathematical modelling

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.

Three-dimensional natural convection in rooms connected to the outside through large openings

This paper is a description of a numerical method that aims at analysing three-dimensional natural convection in rooms with wide openings.A 3D CFD tool is proposed to predict the airflow pattern and the heat and mass transfer inside a heated office room connected to a corridor via a doorway.Results have been compared to experimental data obtained in full-scale : the CFD predictions agree with the experimentally observed features.

Local similarity model of cross-ventilation - Part 1 : Modelling and validation

LES (Large Eddy Simulation) has bben used to simulate cross ventilation under various wind direction angles. A new model, named local similarity model of cross ventilation, is proposed to estimate cross-ventilation flow rate and inflow angle at opening. In order to validate the proposed model, a wind tunnel experiment using a building model was carried out. The results confirm that dynamic similarity is established almost regardless of wind direction angle and position of the opening.

Buoyancy-driven natural ventilation in buildings : experimental and numerical studies

The study of buoyancy-driven natural ventilation in buildings requires windless conditions. It is difficult to conduct on-site measurements since the nature has few windless moments so a full-scale test room placed in a large laboratory environment can create artificially such conditions but it is an expensive method. CFD methods using two different models (RANS and LES) provide an alternative approach to study natural ventilation in buildings.

A correctional prediction for airflow rate of natural ventilation with wind fluctuation

CFD and fluid net models used for natural ventilation designs do not consider the impacts of fluctuating characteristics to the mean airflow rate. This paper presents first a correctional method for predicting mean airflow rate of natural ventilation when the average wind velocity is more important than velocity fluctuation. A correctional coefficient for airflow resistance of multi-zone models is deduced. This method is then applied to a big atrium of a naturally ventilated five floor laboratory.

Evaluation criteria for the air exchange efficiency in naturally ventilated rooms

Natural ventilation is often a highly unsteady phenomenon, therefore steady criteria, very helpful for mechanical systems, cannot be used. This paper presents ideas for evaluating transient flow situations. The theory of the air exchange efficiency is extended to transient flows.

Thermal room modelling adapted to the test of HVAC control systems

A new room model has been developed and validated in order to be used for the assessment of HVAC sensors, assuming non-homogeneous room conditions and distinguishing between different sensor positions. .

Experimental and numerical analysis of a hybrid-ventilated room

This study was undertaken in IEA ECBCS Annex 35 to model a hybrid-ventilated room and to implement control strategies. An experimental cell was designed and simulations were performed after having adjusted the thermal models to experiments. The hybrid ventilation proved more performant than traditional ventilation systems.

Prediction of indoor environmental quality in multizone buildings using zonal models

Prediction of airflow and pollutant transfers in a simple multizone building may use different approaches such as zonal or nodal modeling methods. This paper proposes to improve the modeling of pollutant transport by coupling nodal and zonal models in the SPARK simulation environment.
Nodal model gives mass airflow rates used as boundary conditions in the zonal model to predict pollutants mass transport. Simulation results are compared with experimental data from the 2 zones testing room Minibat.

Analysis method of thermal and lighting environments and its application to the evaluation of office lighting

A method for analyzing the thermal and lighting radiations in offices building has been developed. It enables the simulation of complicated lighting environments composed of a combination of artificial lighting and solar radiation, in ventilated and air conditioned offices.