This paper aims at showing the difference between the two approaches used to evaluate the capture efficiency of a local ventilation system : an experimental research using the tracer gas method ( CO2) and the numerical modelling using CFD code ( STAR-CD). Comparison between the two methods show that the CFD modelling can provide results in good agreement with the experiment.
European radon research and industry collaboration concerted action (ERRICCA2) is establishing a European scientific led industrial forum aimed at reducing risks to health from radiation (principally radon) in the built environment. It brings together 35 organisations from 20 countries.
The main aim of the Tip-Vent project was to provide a contribution o the creation of improved boundary conditions for the application of mechanical ventilation systems with good levels of performance. The project has led to a better understanding of the true performance of ventilation systems, why they perform as they do and what improvements are achievable.
The objective of PV-cooling project was to develop low electricity consumption cooling systems for dwellings and office building, powered through photovoltaic (PV) electricity. Two systems have been developed, one using PV and evaporative air-cooling, the other using PV and ground cooling through buried pipes.
This paper studies the climatic suitability to natural ventilation, which depends on energy saved for cooling and on the presence of driving forces such as wind and buoyancy. It may be assessed by estimating the distribution of temperature differences : difference between indoor and upper limit of comfort zone temperature for the energy saved, difference between indoor and outdoor temperature for the buoyancy effect.
This paper is a presentation of a detailed mathematical simulation along with an experimental investigation of airflow in solar chimneys carried out with an experimental apparatus whose most of the variables could be changed during the experiments. It is a chimney channel with changeable channel thickness and inclination angle.
The simulation model used proved very useful to simulate solar chimneys performance. It can predict flow rates for a wide range of variables.
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.
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.
Due to the renewal of interest for solar chimneys (that convert thermal energy into the kinetic energy of air movement) , experiments were carried out in a controlled environment, with a full-scale chimney, where both air-velocity and air-temperature were measured.
The aim of the project was to get a better knowledge of :
- optimal gap to height ratio
- optimal gap to different heat input ratio
- optimal inclination angle
- methods to estimate the flow rate.
This paper sums up the developments in geophysical fluid dynamics and ocean currents related to dynamical phenomena. Examples from study of ocean flows are given, then several methods for studying nonlinear dynamical phenomena proposed. Those dynamical phenomena can be very significant for smoke control in naturally and hybrid ventilated buildings.
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