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numerical modelling

Thermal plumes above heat sources in rooms with a temperature stratification.

Information on thermal plume characteristics is essential for designing ventilation systems with displacement air supply. Empirical, analytical and computational fluid dynamics are the commonly used approaches to evaluate air temperatures, velocities and airflow rates in thermal plumes above different heat sources. However, only limited information is available on the behavior of thermal plumes in rooms with a temperature gradient along the room height.

Numerical modelling of surface condensation on diffuser for cold air distribution systems.

Condensation on the surfaces of diffuser and cold air dumping are the two major concerns in the application of cold air distribution brought about by the high temperature difference between supply air and room air. Condensation will form if the surface temperature of the diffuser is lower than the dew point temperature of ambient air. The presence of surface condensation can promote growth of unhealthy and smelly mold, and produce unwelcome damage of a structural and/or aesthetic nature. Cold air dumping is a major factor that detracts from thermal comfort in an airconditioned room.

Numerical study of the effectiveness of atrium smoke exhaust systems.

This paper discusses the numerical study of the effectiveness of atrium smoke exhaust systems. This study is part of a project initiated by A SH RAE and the National Research Council of Canada (NRCC), in which both physical and numerical techniques were employed to determine the effectiveness of such systems and to develop guidelines for their design. This paper presents numerical predictions obtained using a computational fluid dynamics (CFD) model and compares the numerical results with the experimental data obtained from tests performed in this project.

Numerical analysis of ventilation system performance by COMIS model.

This research evaluated the performance of four kinds of ventilation systems for dwellings under various conditions by means of numerical simulation. The total number of combinations of various parameters for the calculation was 174. Calculations were performed hourly for indoor air pollutant concentration, humidity and condensation, indoor outdoor pressure difference, airflow rate, and heat energy by ventilation, etc., through the heating season. A multizone infiltration and pollutant transport model (COMIS) was used to perform the simulation.

Numerical simulation of volatile organic compounds dispersion emitted from flooring materials in buildings.

This paper deals with the simulation of VOCs concentration dispersion emitted from flooring material, with the purpose of understanding vocs emission and dispersion mechanisms. A test chamber is examined, whose flooring material emits a number of VOCs. Given the area specific ventilation rate and considering as boundary conditions experimental data for the examined compounds concentration, the dispersion of the vocs concentrations is examined, for two cases, steady state conditions and transient state conditions.

Modelling and measurement of soil gas flow.

There are two main soil gases of current concern to human health. These are radon, which is a carcinogen, and landfill gas, which is explosive and toxic. Both can be found at significant levels in the soil below buildings in certain locations in the country. It is a responsibility of the Building Research Establishment to find cost effective ways to protect new and existing buildings from the entry of these gases into buildings.

Natural ventilation by thermal buoyancy with several openings and with temperature stratification.

Based on the fundamental flow equations, a set of formulas is derived for air velocities, temperature differences and ventilation rates in relation to number of openings, opening areas, net heat input, building geometry, and temperature stratification. The use of the formulas is illustrated on a three-storeyed office building.

Measurements and Predictions of Room Airflow Patterns using Different Turbulence Models

To evaluate the performance of different turbulence models in room airflow applications measurements in a test room will be compared to numerical calculations. The measurements are taken in a 6 x 4 x 3 m3 room with two heated dummies and a computer. Zero heat flux boundary conditions are achieved by controlling the inner and outer wall temperature. Two different ventilation systems will be examined in order to get momentum and buoyancy driven flow fields. Temperature measurement and Particle Streak Tracking data will be compared to the numerical predictions.

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