The proposed local dynamic similarity model can select an adequate discharge coefficient to match the approaching flow angle. This is an improvement over the conventional orifice flow model where the discharge coefficient is set to a fixed value. The accuracy of predicting ventilation flow rates for an isolated cross-ventilation model is greatly improved when the discharge coefficients actually decrease with change of wind direction.
Pressure loss mechanism at the inflow opening of Cross-Ventilation is studied by detailed analysis of LES results. Manipulation of energy transfer equation through inflow openings suggests that reduction of discharge coefficient should be originated from dynamic pressure in tangential direction and should be observed as increased static pressure at the opening.
The present paper evaluates indoor thermal environment, cooling efficiency and energy consumption between a floor-based system and a ceiling-based system using a mock-up model in cooling period. The experimental chamber has a UFAC, underfloor air conditioning system and a ceiling-based system. And the experiments are set with practical internal load conditions including occupants, lighting units, and heat sources (office automation equipment). The following were compared and evaluated;
1) the vertical and horizontal temperature distribution,
The aim of that study is to establish characteristic building parameters and to analyse the night ventilation effect with these parameters. Measurements were made thanks to a parametric model and a building simulation programme.
An optimal placement of outside air intakes is important for a good IAQ protection. A proper intake placement can also reduce the need for filtration, and reduce re-entrainment of chemical emissions.
The microbiological quality of air was studied in a bread-making factory (100t/day). It wasnoticed that the microorganism density varies along the fabrication hall, a high number of microorganisms, especially moulds, being registered in the bread cooling area and the storage room. In the bread cooling area predominate Penicilllium expansum spores, this mould being able to develop at low aw values and determining the bread spoilage.
The paper presents an extension of a two-equation turbulence model to predict the airflow fordisplacement ventilation systems. First, every flow effect is investigated separately natural convection along a vertical wall and above a person as well as mixed convection at the floor. Second, a CFD analysis of a test room is compared to full scale measurements. The modified two-equation turbulence model leads to a good agreement of the measurements and the calculations.
This paper examines airflow in rooms for a displacement ventilation system using threedimensionalCFD. A parametric study is executed for a typical office room with a dimension of 6m by 6m by 3m height according to a variety of supply air velocities, supply air temperatures and heat sourceconditions. A finite volume method and standard k- e turbulence model is employed to solve the governing equations. As a result, the temperature field in the modeled room for a displacement ventilation system is concluded according to a variety of the above parameters.
The values of the normalized concentration in the occupied zone (Cn) in an office space arecalculated by CFD for five different ventilation systems and the minimum ventilation rate which maintains the average concentration in the occupied zone under the regulated value is analyzed. Energy consumptions associated with the change in ventilation rate are analyzed. In this analysis, for most ventilation systems, the value of Cn is around 1.0, but for large circulation flow ventilation systems it changes greatly depending on the supply inlet velocity and temperature.
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