Modeling air exchange in office premises using a microperforated fabric air duct

Summary

The issues of improving the quality of the internal environment of an office building using an advanced air dispersion device – a fabric air duct with micro-orifices are considered. The advantage of this device is supplying the incoming air by jets with a low impulse allowing to locate the devices near the working space in offices eliminating the risk of drafts at the working places. The purpose of the work is a comparative numerical calculation of the efficiency of arranging the air exchange in an office building with two air supply schemes: through supply grilles and through a fabric air duct with microperforation. Modeling was carried out using the commercial STAR-CCM + software package. The system of Reynolds equations with closure using the k-ω SST turbulence model (Mentor) is used to describe the air movement. As part of the study, data on the nature of the change in temperature and air speed along the height of the working area of the office were obtained. It has been determined that while air is supplied through the supply grilles, the temperature (23.3–27.2 °C) and air speed (0.06–0.22 m/s) meet the permissible microclimate standards (GOST 30494-2011); while arranging the air exchange with the use of a microperforated air duct they correspond to the optimal parameters (temperature 23.1–25.4 °С, air speed 0.09–0.13 m/s) that are comfortable for the human body. Thus, the use of a microperforated air duct enhances the efficiency of heat surplus assimilation in comparison with traditional air distribution devices (ventilation grilles).

Key words

numerical simulation , ventilation , control volume approach CFD , air distribution , heat-mass exchange , microperforated fabric air duct

Designing drainage systems of flooded areas on the basis of computer simulation

Summary

To make hydrogeological calculations of drainage systems for protecting territories from floods the methods of analogy, analytical and computer simulation are used. The method of computer simulation as applied to designing drainage systems on the territory of the Imeretinskaia Lowland of the Krasnodar Area is closely considered. The analysis of the model map of ground water depth after territory upfilling and building development provided for identifying the areas to construct the systems of engineering protection from flooding. The basic design solution of reducing ground water level on the flooded territories is constructing horizontal subsoil pipe drainage with filtering bedding or radial horizontal drainage. Depending on the results of the mathematical simulation of the hydrogeological conditions on the protected area and hydrogeological calculations pipe drainages of perimeter, linear or systematic (areal) type are constructed. Ground water by gravity is diverted into open-channel flows provided the proper ecological justification is available. As may be required automated drainage pumping over stations are established. The developed concept allows reducing and maintaining ground water level at the permissible depth.

Key words

filtration , drainage system , numerical simulation , territory underflooding , ground water , hydroisohypses

Numerical Simulation for Substantiation of the Engineering Protection System in the City of Kazan

Summary

It is told about the process of creating a software package for numerical simulation of the drainage system in the city of Kazan. The calculations to determine the optimal mode of its operation are presented. The problem of optimizing the operating mode of pumping stations is formalized and presented as a problem of multicriterion optimization: reducing the potential damage as a result of underflooding at minimization of energy costs. The decision has been found with the help of an evolutional algorithm. On the basis of calculations carried out the recommendations for optimization of the pumping stations operation mode in the city of Kazan making it possible to reduce expenditures for operation of the engineering protection system for preservation of urban territories from underflooding have been given.

Key words

ground water , underflooding , drainage , numerical simulation , software package , minimization of damage , evolutional algorithm , optimization