English

The flow rate in thermal plumes are influenced by many factors. Influence by enclosing walls is one of them. This article presents simple symmetry considerations to calculate the flow rate in such flows, and they are experimentally verified as regards wall plumes. When the flow takes place near to enclosing walls the entrainment is influenced and a reduction of the flow rate is observed. For displacement ventilation this means a reduction of the stipulated necessary ventilating air flow rate when an air quality based design method is used.

Simulation models basing on 2-dimensional finite-difference approach were developed for the steady-state and dynamic analyses of the thermal coupling of leakage airflows and building components. The considered types of leakage flows were crack flow and filtration through porous materials.

The paper presents an original computer code for the analysis of contaminant diffusion in rooms developed at the Politecnico di Torino and its experimental validation by means of a test facility located at the University of Basilicata (Potenza). Thevelocity fields in isothermal conditions, together with localages of the air, have been analysed and compared, with different ventilation strategies and number of air changes.

Reverberant sound excitation and the sound intensity technique have been used for the measurement of the sound transmission loss of narrow slits in rigid walls. A series of experiments was conducted to determine the transmission loss of slit shaped apertures. The measured transmission loss was in good agreement with existing approximate theories over their accepted ranges of validity. However, the effect of viscosity in small apertures was found to be significant and to vary systematically with the dimensions of the apertures.

The computer programs published so far have enabled the calculation of airflows at constant temperatures or of air temperatures at constant airflows. The first version of a new microcomputer program has now been developed in which the airflows and temperatures are calculated simultaneously. The time dependency of temperatures, airflows and contaminant concentrations is considered in the calculation method. The source strength of contaminants, outdoor air temperature, wind velocity and direction, convection and radiation loads can all be freely scheduled.

Numerical modelling is performed to predict air movement, thermal comfort level and contamination distribution within an open office space. The office located in the building interior has a concentrated thermal load at its center and is conditioned by cool air delivered from a ceiling-mounted linear diffuser. the air velocity and temperature distributions and contaminant dispersion in the office are calculated for three different cooling loads and air exchange rates with a three-dimensional turbulent finite difference model.

Results of 3-D computational fluid dynamic simulations of the air flows, temperature distribution and contaminant remove efficiencies for typical workstation configurations which include the option for localized supply of outdoor air will be presented. A typical office configuration including desks, partitions, localized heat and contaminant sources will be modelled. The results will be compared to similar simulations the same workstation environment using ceiling supply and return plenum configurations.

The paper discusses methods to set boundary conditions at the air supply opening in predictions of room air flows with computational fluid dynamics. The work is a part of the International Energy Agency project "Air Flow Patterns within Buildings", Annex 20. The air supply terminal in the Annex 20 project is a commercial diffuser which creates a stagnation region and a complicated wall jet below the ceiling. Fairly well predictions in the wall jet region were obtained replacing the diffuser by a simple opening which has the same momentum flow as in the diffuser.

Modern inlet devices applied in the field of ventilation of rooms are getting more complex in terms of geometry in order to fulfil the demand for thermal comfort of the occupants in the room and in order to decrease the energy consumption This expresses the need for more precise calculation of the flow jield. In order to apply CFD for this purpose it is essential to be able to model the inlet conditions precisely and effectively, in a way which is comprehensible to the manufacturer of inlet devices and in a way which can be coped by the computer resources.

Combined ventilation and heating systems in floors demand extensive investigations about the heat transfer before they could be installed in residential buildings. For basic investigation about the heat transfer two experimental plants with different duct geometries are build in a laboratory of the University of Essen. Especially the measurements of temperature on different places of the plants are taken to determine the heat transfer at the two floors.