Objective
The proposed work is related to the improvement of the working environment conditions. The objective is the development of a numerical model for the prediction of the concentration distribution in a closed space of a pollutant which can be toxic or flammable, under turbulent free or forced convection conditions and in presence of obstacles. An accurate time- dependent description of the pollutant concentration is a prerequisite in order to minimise the man-exposure and to optimise the performance of the ventilation system.
The work is related to the improvement of working environment conditions. The objective is the development of a numerical model of the prediction of the concentration distribution in a closed space of a pollutant which can be toxic or flammable, under turbulent free of forced convection conditions and in presence of obstacles. An accurate time dependent description of the pollutant concentration is a prerequisite in order to minimize the man exposure and to optimize the performance of the ventilation system.
Progress to end 1991
Under the label "Working Environment" (WE) a set of multidisciplinary research projects are under way in many countries with the general purpose of reducing the exposure of workers to the risks of several kinds associated to the conditions in which the work is performed.
The main topics of WE research projects are related to risk assessment/prevention, occupational medicine, toxicology, occupational accidents (fire protection, gas/dust explosions, electrical hazards), noise and vibration analysis, ergonomy, industrial psychology, protective clothing and equipment, detection and dispersion of gases and vapours in closed spaces. A classification of the research topics, as proposed by the French INSR (Institute National de Recherche et de securite), is given below:
1. Possible risks related to the chemical environment
- toxicological studies of mineral or organic industrial products considering the effects on air-wind passage, central nervous, cardiac, hepatic and renal systems. Concerning the long term effetcs, studies of carcinogenesis and mutagenesis.
- Surveillance of the working environment:
. Cartography of atmospheric pollutant concentrations as a function of sectorial activities.
. Methodological studies of chemical metrology.
- Detection and measure of toxic permeation.
- Epidemiological studies (effects due to pollutant exposure).
2. Risk related to physical environment
- Noise related studies: metrology, acoustic, noise reduction techniques, physiological effects.
- Vibration related studies.
- Studies on body loading and positions at work.
- Multinoise studies.
Ventilation and pollutant detection:
. Methodological studies (hydrodynamic simulations).
. Experimental studies on the performance of ventilation systems.
3. Accidents and working conditions
- Risk analysis and prevention measures.
- Industrial safety and accident analysis.
- Risk connected to manual and automatic maintenance.
- Risk related to gravity force effects.
- Risk related to electronic systems.
- Risk related to machinery and fittings.
- Individual and collective protections.
The theme "Ventilation and pollutant transport" has been identified as appropriate to be considered as a possible future research project for the STI and a literature review has been started in 1991. Main objective of the hydrodynamic simulation studies is the development of a predictive tool to assess the time-dependent concentration distribution of a pollutant in a confined domain, under turbulent, free and forced convection conditions.
Detailed description of work foreseen in 1992
The first step of the work foreseen is the continuation of the assessment of the state of the art and of the calculation needs in the area of ventilation and pollutant detection. A. survey on the available tools and on the current research in progress has been already started and has given indications that there is a need for efficient, accurate and robust multidimensional computer models. If this scenario is confirmed, the planned work will consist of implementing suitable modifications to a 3-D computer code (TRAFLU) developed at JRC-Ispra for solving natural or forced convection problems, in order to include a turbulent model and the possibility to treat two fluid mixtures. The formulation will be based upon the concept of the fractional step method where the convection-diffusion phase will be solved by using implicit least-squares, space-time finite elements, which appear to be ideally suited to produce an efficient discrete approximation of the flow equations. The proposed numerical method leads to unconditionally stable and second-order accurate schemes; it has been extensively tested in the previous version of the code TRAFLU (excluding turbulence and for a single fluid). the main algorithm and the set of available boundary conditions will be revised to meet the requirements of the two fluid and turbulent formulations adopted.
Expected benefits are: an accurate description of the flow in order to minimise the man-exposure and to optimise the performance of the ventilation system (positions of ventilation ports, flow rate values). Furthermore, the optimisation of the positions for the detection devices would be possible. After validation of the numerical model proposed, it would be possible to rely mainly on computer predictions avoiding most of the costly experimental studies on the performance of ventilation systems.
Short description of evolution of work in 1993
Extensions foreseen concern the treatment of aerosols (solid particles-dust transport) and the introduction of chemically reactive fluids.
Topic(s)
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21020 Ispra
Italy