Submitted by Maria.Kapsalaki on Fri, 03/03/2023 - 09:34
Building system engineering can help decrease the risk of being infected by the aerosol which contains virus-laden droplet nuclei. Many techniques can help decrease the concentrations of particles. This paper focuses on the economic renovation of the existing ventilation system of a public commercial space, a small meeting room in Kuijpers, Leiden, to decrease airborne transmission of respiratory infectious diseases.
Submitted by Maria.Kapsalaki on Thu, 11/23/2017 - 15:51
Experimental investigation of ceiling circular grille air jets was conducted in a full-scale entirely controlled test room (6.2 x 3.1 x 2.5 m). Our case study is based on a realistic ventilation system configuration: it introduces a plenum box, two air exhausts, as well as a vertical wall near the air inlet. Analyses were initially concentrated at the air inlet region since it is the zone having strong gradients. Deviations concerning the trajectory of the actual jet were observed with respect to the theoretical jet.
Submitted by Maria.Kapsalaki on Wed, 06/18/2014 - 11:18
Bases on the concept of task/ambient ventilation, fresh air can be decoupled from re-circulated air so as to improving ventilation effectiveness in breathing zone. Ceiling mounted high velocity circular jet diffusers, which are regarded as remote personalized ventilation air terminal devices (PV ATDs) without affecting room aesthetic effects, can be utilized to supply fresh air without causing draft rating because tropically acclimatized occupants prefer slightly higher air movement. Under-floor air diffusers are used to supply re-circulated air.
Submitted by Maria.Kapsalaki on Wed, 06/18/2014 - 11:16
This study developed a drift-flux model for particle movements in turbulent indoor airflows. To account for the process of particle deposition at solid boundaries in the numerical model, a semi-empirical deposition model was adopted in which the sizedependent deposition characteristics were well resolved. After validation against the experimental data, the drift-flux model was used to investigate human exposures to particles in three normally-used ventilation types: mixing ventilation (MV), displacement ventilation (DV), and under-floor air distribution (UFAD).
Submitted by Maria.Kapsalaki on Tue, 11/05/2013 - 18:06
Air quality in offices depends on the ventilation system ability to remove contaminants from the occupied zone. In a low polluted building air quality mainly depends on the human presence and carbon dioxide is normally used as indicator of human bioeffluents.
Submitted by Maria.Kapsalaki on Thu, 10/31/2013 - 09:59
Stratum ventilation has been proposed to cope for elevated indoor temperature recommended by governments in East Asia. TRNSYS is used for computation of the space cooling load and system energy consumption. A typical Hong Kong office is investigated. Compared with mixing ventilation and displacement ventilation, stratum ventilation derives its energy saving potential largely from the following two factors: a reduced ventilation load and increased coefficients of performance (COP) for chillers.
The 3DFLOW code has been developed based on:
· The standard three-dimensional K-epsilon two-equation turbulence model;
· A modification for buoyancy effects;
· Wall functions applied to deal with solid boundary conditions;
· An adaptation of the SIMPLE algorithm.
The representative indoor air flows in conditioned spaces, including downward mixing, partition and displacement ventilation cases, were simulated and analysed in detail using the 3DFLOW code. Good agreement was found between the numerical predictions and experimental data.
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.
This paper sums up the results of a study on the internal partitioning with its effects on the room air quality along with the ventilation performance. Physical tests and numerical modeling for a CFD simulation were used to evaluate different test conditions that employed mixing ventilation from the ceiling.
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.