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mathematical modelling

Assessing multi-zone airflow simulation software

Several standard multizone modeling programs, in order to improve their computational efficiency, make a number of simplifying assumptions. This paper examines how those assumptions reduce the solution times and memory use of the programs, but at the cost of restricting the models they can express.

Thermal comfort in a mixing ventilated room with high velocities near the occupied zone

Experimental results in a testing room with mixing ventilation were used to define two new ways of designing the inlet airflow in order to ensure comfort. The first way uses the assumption that air velocities are only a function of the Archimedes number, which provides curves showing air velocity in the occupied zone as function of inlet air temperature and velocity. The second way results from an analytical calculation of the penetration length of the air jet in the room and the distance where it enters the occupied zone.

Stability analysis of the mechanism of jet attachment to walls

The paper gives an explanation of the phenomenon of attachment of a cold air jet to a ceiling, based on a theoretical analysis. A formula to calculate the distance between the blowing slot and the point where the cold air jet will separate from ceiling is given. The results of calculations using this formula show good agreement with experimental data.

Assessment of velocity fields in the vicinity of rectangular exhaust hood openings.

Presents new empirical formulae for the prediction of the air velocity in front of rectangular (slot) openings. Infers the equations from an experimental study of a common type of local exhaust opening. The formulae describe the three-dimensional velocity field near a rectangular exhaust hood, providing the velocity gradients along suitable directions, parallel to the slot axis. Testing of the formulae showed a good fit to the experimental data.

Design of ventilation systems in industrial buildings. A computational approach of displacement ventilation in paper industry.

In this paper, the ventilation of a “crêpe” paper-processing workshop containing dryers, which generate a high thermal load, is considered. Displacement ventilation has been used for many years in industries with high thermal load. The main ventilation de

"Humid Air" and cooled walls.

The humidity of room air is a necessary influence of design under the aspects of thermalbehavior, technology and conservation.The moisture absorption in the walls through sorptive materials or dehumidification on thecold window surface by dew point condensation is low because of the new thermalcharacteristics of these components.The moisture load of a room briefly or also continuously, caused by technological processesor the users cant be compensated.Today, the walls are used like a floor heating system.

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