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displacement ventilation

Determining ventilation strategy to defend indoor environment against contamination by integrated accessibility of contaminant source (IACS)

How to avoid or reduce the influence of suddenly released contaminant when emergency occurs ? A 3D Full scale room with displacement and mixing ventilation system is numerically studied assuming contaminant released at certain positions in the room. IACS is adopted as an index that can be applied to determine ventilation strategy with the aim of defending indoor environment against contamination.

Extension of a Two-Equation Turbulence Model for Displacement Ventilation Systems

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.

Parametric Study on a Displacement Ventilation System Using Three-Dimensional CFD

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.

Use of simulation in the design of the climate control system for a new concert hall and multi purpose spaces in a convent in Coimbra - Portugal

This paper presents the results of the application of building thermal simulation in the design of anew concert hall and refurbishment of interior spaces in the So Francisco Convent in Coimbra, Portugal. The proposed design uses displacement ventilation in all spaces, mechanically driven in the auditorium and hybrid in the convent rooms. A displacement ventilation model, recently implemented in EnergyPlus, is used to predict energy consumption and thermal comfort.

Lower energy cost and less sick leave with displacement ventilation versus mixing ventilation

Experiences from cleanroom installations has frequently shown that displacement ventilation has a much higher efficiency than mixing ventilation with respect to particle and CO2 reduction, cooling efficiency etc. Another cleanroom experience is that low particle concentration benefits asthma and allergy sufferer. Low particle concentrations reduces the impact of other pollutants and enhance the quality of life for everybody. In an office, the level of discomfort this means less tiredness, better concentration and lower absenteeism.

Airborne particle concentrations in two classrooms with mixing and displacement ventilation

Airborne particle concentrations of 20 nm to 10 µm particles were studied in two similar classrooms in a school. One classroom was ventilated by mixing ventilation with supply air filtration and one by displacement ventilation without supply air filtratio

Displacement flow air supply through a raised floor covered by carpet - possible mistakes by wrong design and installation

Large spaces with high thermal loads and high air flow rates air conditioned by displacement flowsometimes require air supply through the raised floor. One favoured solution is to cover the perforated floor by an air permeable carpet. Successful solutions of this type of air outlets exist in many buildings in Germany since many years and work successfully. But design and installation require some knowledge which partly may have been lost in recent years. In newer buildings many difficulties appeared.

A simple model for heat transfer in displacement-ventilation

This paper presents a simple model for vertical temperature profile and heat transfer predictionin displacement ventilation. The fully-mixed room air approximation that is currently used in most whole building analysis tools is extended to a three node approach, with the purpose of obtaining a first order precision model for displacement ventilation systems. The use of three nodes allows for improved prediction of thermal comfort and overall building energy performance in low energy cooling strategies that make use of unmixed stratified ventilation flows.

Numerical analysis of particle behaviors in indoor air using Lagrangian method

As particles in room air can cause lung diseases, it is important to study how they are transported and dispersed in buildings. This investigation numerically studied particle dispersion by using the Lagrangian approach. The turbulent airflow is solved by the RNG k-e model; and a discontinuous random walk (DRW) model is applied to account for the stochastic effect of particle movement in turbulent flow. The computed results agree reasonably well with the experimental data for particle dispersion in a wind tunnel.

Plane Stratified Flow in a Room Ventilated by Displacement Ventilation

The air movement in the occupied zone of a room ventilated by displacement ventilation exists as a stratified flow along the floor. This flow can be radial or plane according to the number of wall-mounted diffusers and the room geometry. This paper addresses the situations where plane flow is obtained and a semianalytic expression for the velocity level in the occupied zone is given.

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